Device, controller and method for determining rock breakthrough pressure

Abstract

The invention discloses a device, a controller and a method for determining rock breakthrough pressure, and the device comprises a pressure difference generation device which is used for providing injection pressure difference for injection fluid; the core holder is used for placing a to-be-tested core with saturated formation water and heating the to-be-tested core to the formation temperature; the confining pressure pump is used for providing the required confining pressure for the clamping device to serve as formation pressure; the nuclear magnetic resonance testing device is used for performing nuclear magnetic testing on the core of the saturated formation water to obtain the water saturation of the core; and the controller is used for controlling each component to work so as to obtain the water saturation of the rock core when the operation of injecting the non-wetting phase fluid into the rock core to be measured is executed under the injection pressure difference of different periods. The rock breakthrough pressure can be efficiently and accurately determined based on the on-line fluid saturation test.

Description

Technical Field

[0001] This invention relates to the fields of seepage mechanics and reservoir physics, and in particular to a device, controller and method for determining rock breakthrough pressure. Background Technology

[0002] This section is intended to provide background or context for the embodiments of the invention set forth in the claims. The description herein is not an admission that it is prior art simply because it is included in this section.

[0003] Breakthrough pressure is a crucial fundamental data point for research in oil and gas field development and carbon dioxide geological storage. It is an important parameter for evaluating caprock sealing, assessing oil and gas field enrichment capacity, and determining the safety of carbon dioxide geological storage. Breakthrough pressure is currently measured primarily through two methods: mercury intrusion porosimetry and displacement intrusion porosimetry. These two methods and their limitations are discussed below.

[0004] Mercury intrusion porosimetry (MIP) is an indirect method for measuring breakthrough pressure. It involves recording the amount of mercury injected into a core at different breakthrough pressure points and calculating the corresponding pore radius and breakthrough pressure. However, this method has significant limitations. For example, mercury, as a fluid, cannot reflect the interaction between water and rock minerals under formation conditions, leading to a discrepancy between the indirectly calculated breakthrough pressure and the actual gas-water breakthrough pressure. Furthermore, mercury is a toxic and hazardous chemical, difficult to recover and treat, and prone to environmental pollution.

[0005] Displacement methods (such as stepwise pressure displacement) are one of the main methods for determining rock breakthrough pressure, primarily based on the industry standard SY / T 5748-2020 "Method for Determining Rock Gas Breakthrough Pressure". This testing method is closest to the definition of breakthrough pressure and better reflects the situation where non-wetting fluid breaks through and begins to displace pore water. This type of method mainly determines whether the injected fluid has broken through the core by observing the fluid output (such as bubbles) and changes in outlet pressure at the core holder. However, during breakthrough pressure testing, the core allows fluid to break through, but the flow velocity and flow rate are extremely low. To overcome the end-face effect, the length of the core used for breakthrough pressure testing typically needs to be 1.0-2.5 cm. This makes it difficult to accurately determine whether the fluid has broken through at the set pressure. Although increasing the pressure increment can shorten the testing cycle, excessively large stepwise pressures can affect testing accuracy. For these reasons, the displacement method for testing rock breakthrough pressure is extremely time-consuming, often lasting a week or several weeks, making it difficult to balance accuracy and efficiency. To more accurately determine the pressure point at which fluid begins to flow in rock, existing technologies include adding a sapphire window to the rear end of a core holder to observe bubbles (gas flow) and measure the rock gas breakthrough pressure. However, this method still requires long-term observation of changes in the pressure of the bubbles at the production end or the outlet to determine the occurrence of flow in the rock, and cannot fundamentally solve the problem of quickly and accurately determining the pressure and time point at which fluid breaks through the rock. Summary of the Invention

[0006] This invention provides an online fluid saturation testing device for determining rock breakthrough pressure, enabling efficient and accurate determination of rock breakthrough pressure based on online fluid saturation testing. The device includes: a pressure differential generating device, a core holder, a confining pressure pump, a nuclear magnetic resonance (NMR) testing device, and a controller; wherein:

[0007] Differential pressure generating device, used to provide injection differential pressure for injecting non-wetting phase fluid;

[0008] A core holder is installed inside the test chamber of the nuclear magnetic resonance testing device to hold a core sample saturated with formation water and heat it to the formation temperature, maintaining the temperature at that temperature.

[0009] A confining pressure pump, connected to a core holder, is used to provide the required confining pressure to the core holder as the formation pressure of the core to be tested.

[0010] Nuclear magnetic resonance (NMR) testing equipment is used to perform NMR testing on core samples saturated with formation water to obtain the water saturation of the core samples.

[0011] The controller is used to control the operation of the differential pressure generating device, core holder, confining pressure pump, and nuclear magnetic resonance testing device under the formation temperature and pressure environment, so as to obtain the water saturation of the core under different periodic injection differentials when performing the operation of injecting non-wetting phase fluid into the core saturated with formation water.

[0012] This invention also provides an apparatus for determining rock breakthrough pressure, which is used to efficiently and accurately determine rock breakthrough pressure based on online fluid saturation testing. The apparatus includes:

[0013] The acquisition unit is used to acquire the preset initial injection differential pressure.

[0014] The cyclic unit, using a preset initial injection differential pressure as the initial value, repeatedly executes the following steps for determining the rock breakthrough pressure based on online fluid saturation testing. Each cycle performs the following operations:

[0015] The water saturation of the test core is obtained when the operation of injecting non-wetting phase fluid into the test core saturated with formation water is performed under the current cycle injection pressure differential; the test core is under formation temperature and pressure environment;

[0016] Within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference does not change, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed with the next cycle injection pressure difference.

[0017] Within a preset time period, the cycle ends when the water saturation of the core sample begins to change under the current cycle injection pressure differential.

[0018] The unit is defined as the injection pressure difference corresponding to the point when the water saturation begins to change, which is used as the breakthrough pressure of the core sample to be tested.

[0019] This invention also provides an online fluid saturation test controller for determining rock breakthrough pressure, used to efficiently and accurately determine rock breakthrough pressure based on online fluid saturation testing. The controller includes:

[0020] The first control unit is used to control the core holder to heat to a preset formation temperature and maintain it at the formation temperature; the core holder contains a core sample saturated with formation water and is set inside the test chamber of the nuclear magnetic resonance testing device.

[0021] The second control unit is used to control the confining pressure pump to provide the required confining pressure to the core holder as the formation pressure of the core to be tested by injecting fluid when the core holder is kept at a constant temperature of the formation.

[0022] The third control unit is used to control the nuclear magnetic resonance testing device to perform nuclear magnetic resonance testing on the core sample saturated with formation water under the formation temperature and formation pressure.

[0023] The fourth control unit is used to control the water saturation of the test core when the pressure difference generating device obtains the water saturation of the test core during the operation of injecting non-wetting phase fluid into the test core saturated with formation water under different periodic injection pressure differences.

[0024] This invention also provides a method for determining rock breakthrough pressure, which is used to efficiently and accurately determine rock breakthrough pressure based on online fluid saturation testing. The method includes:

[0025] Obtain the preset initial injection differential pressure;

[0026] Using a preset initial injection pressure differential as the initial value, the following steps for determining the rock breakthrough pressure based on online fluid saturation testing are executed cyclically, with the following operations performed in each cycle:

[0027] The water saturation of the test core is obtained when the operation of injecting non-wetting phase fluid into the test core saturated with formation water is performed under the current cycle injection pressure differential; the test core is under formation temperature and pressure environment;

[0028] Within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference does not change, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed with the next cycle injection pressure difference.

[0029] Within a preset time period, the cycle ends when the water saturation of the core sample begins to change under the current cycle injection pressure differential.

[0030] The injection pressure difference corresponding to when the water saturation begins to change is taken as the breakthrough pressure of the core sample to be tested.

[0031] This invention also provides an online fluid saturation test control method for determining rock breakthrough pressure, which is used to efficiently and accurately determine rock breakthrough pressure based on online fluid saturation testing. The control method includes:

[0032] The core holder is heated to a preset formation temperature and maintained at that temperature. The core holder contains a core sample saturated with formation water and is placed inside the test chamber of the nuclear magnetic resonance testing device.

[0033] When the core holder is kept at a constant temperature at the formation temperature, the confining pressure pump is controlled to provide the required confining pressure to the core holder by injecting fluid as the formation pressure of the core to be tested.

[0034] Under the aforementioned formation temperature and pressure, the nuclear magnetic resonance testing device is controlled to perform nuclear magnetic resonance testing on the core sample saturated with formation water.

[0035] The water saturation of the test core was measured when the non-wetting phase fluid was injected into the test core saturated with formation water under different periodic injection pressure differentials by the control pressure differential generation device.

[0036] This invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described method for determining rock breakthrough pressure and the online fluid saturation test control method.

[0037] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for determining rock breakthrough pressure and the online fluid saturation test control method.

[0038] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for determining rock breakthrough pressure and the online fluid saturation test control method.

[0039] Compared to existing technologies where fluid flow is allowed to break through the core during pressure testing, resulting in extremely low flow rates and volumes, and where the core used for pressure testing is often quite long to overcome end-face effects, making it difficult to accurately determine whether fluid has broken through under a set pressure, the present invention provides a superior solution for determining rock breakthrough pressure. This solution is time-consuming, often lasting a week or several weeks, making it difficult to balance accuracy and efficiency. The online fluid saturation test allows for real-time detection of even small steps at the interface between the wetting and non-wetting phases, even as the injected fluid just begins to enter the core. This enables rapid and accurate identification of the process where the injected fluid breaks through capillary pressure into the core, without waiting for the fluid to slowly flow through the core and exit from the outlet. Therefore, this invention can efficiently and accurately determine rock breakthrough pressure based on online fluid saturation testing, which is significant for evaluating caprock sealing, assessing oil and gas field enrichment capacity, and assessing the safety of carbon dioxide geological storage. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0041] Figure 1 This is a flowchart illustrating the method for determining rock breakthrough pressure in an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the online fluid saturation testing device for determining rock breakthrough pressure in an embodiment of the present invention;

[0043] Figure 3a This is a schematic diagram of a two-dimensional online fluid saturation test image when the core is completely saturated with brine in an embodiment of the present invention;

[0044] Figure 3b This is a schematic diagram of a two-dimensional online fluid saturation test image of the core after breakthrough in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of the water saturation profile at different locations before and after the measured fluid breaches the core in an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the device for determining rock breakthrough pressure in an embodiment of the present invention;

[0047] Figure 6This is a schematic diagram of the system for determining rock breakthrough pressure in an embodiment of the present invention;

[0048] Figure 7 This is a flowchart illustrating the online fluid saturation test control method for determining rock breakthrough pressure in an embodiment of the present invention.

[0049] Figure 8 This is a schematic diagram of the structure of the online fluid saturation test controller for determining rock breakthrough pressure in an embodiment of the present invention;

[0050] Reference numerals: 1. Injection pump; 2. Intermediate container; 3. Core holder; 4. Confining pressure pump; 5. Nuclear magnetic resonance testing device; 6. Back pressure pump; 7. Controller; 8. Device for determining rock breakthrough pressure; 9. Outlet separation metering component. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0052] To address the problems of poor accuracy and low efficiency in current methods for determining rock breakthrough pressure due to difficulties in fluid flow assessment, this invention proposes a scheme for determining rock breakthrough pressure. This scheme is based on online fluid saturation testing and imaging analysis technology. By creatively introducing high-temperature and high-pressure online fluid saturation testing technology, it observes the water saturation and two-phase fluid interface within the rock core in real time, efficiently and accurately determining the moment when the fluid breaks through the rock, thus obtaining the rock breakthrough pressure. This scheme can significantly improve the accuracy and efficiency of rock breakthrough pressure testing. This technology is of great significance for evaluating caprock sealing, assessing oil and gas field enrichment capacity, and evaluating the safety of carbon dioxide geological sequestration. The following is a detailed description of this scheme for determining rock breakthrough pressure.

[0053] Figure 1 This is a flowchart illustrating the method for determining rock breakthrough pressure in an embodiment of the present invention, as shown below. Figure 1 As shown, the method includes the following steps:

[0054] Step 801: Obtain the preset initial injection differential pressure;

[0055] Step 802: Using the preset initial injection pressure differential as the initial value, repeatedly execute the following steps for determining the rock breakthrough pressure based on online fluid saturation testing. The following operations are performed in each cycle:

[0056] Step 8021: Obtain the water saturation of the core sample when the operation of injecting non-wetting phase fluid into the core sample saturated with formation water is performed under the current cycle injection pressure differential; the core sample is under formation temperature and pressure environment;

[0057] Step 8022: Within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference has not changed, the injection pressure difference is increased to obtain the next cycle injection pressure difference, and the next cycle operation is performed with the next cycle injection pressure difference.

[0058] Step 8023: Within a preset time period, when the water saturation of the core sample under the current cycle injection pressure differential begins to change, the cycle ends;

[0059] Step 803: The injection pressure difference corresponding to when the water saturation begins to change is taken as the breakthrough pressure of the core sample to be tested.

[0060] The method for determining rock breakthrough pressure provided in this invention involves the following steps during operation: acquiring a preset initial injection pressure difference; using the preset initial injection pressure difference as the initial value, cyclically executing the following steps for determining rock breakthrough pressure based on online fluid saturation testing, with each cycle performing the following operations: acquiring the preset initial injection pressure difference; using the preset initial injection pressure difference as the initial value, cyclically executing the following steps for determining rock breakthrough pressure based on online fluid saturation testing, with each cycle performing the following operations: acquiring the water saturation of the core sample under the current cycle injection pressure difference when performing the operation of injecting non-wetting phase fluid into a core sample saturated with formation water; the core sample being under formation temperature and pressure conditions; within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference has not changed, increasing the injection pressure difference to obtain the injection pressure difference for the next cycle, and performing the next cycle operation with the next cycle injection pressure difference; within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference begins to change, ending the cycle; and using the injection pressure difference corresponding to the point where the water saturation begins to change as the breakthrough pressure of the core sample.

[0061] Compared to existing technologies where fluid flow is allowed to break through the core during breakthrough pressure testing, resulting in extremely low flow rates and volumes, and where the core used for breakthrough pressure testing is often quite long to overcome end-face effects, making it difficult to accurately determine whether fluid has broken through at the set pressure, the method for determining rock breakthrough pressure provided in this invention offers the following advantages: During online fluid saturation testing, even when the injected fluid has just entered the core and the interface between the wetting and non-wetting phases has only advanced a small step, it can be detected in real time. This allows for rapid and accurate identification of the injected fluid breaking through the capillary pressure into the core, without waiting for the fluid to slowly flow through the core and exit from the outlet. Therefore, this invention can efficiently and accurately determine rock breakthrough pressure based on online fluid saturation testing, which is of great significance for evaluating caprock sealing, assessing oil and gas field enrichment capacity, and assessing the safety of carbon dioxide geological storage. The method for determining rock breakthrough pressure will be described in detail below.

[0062] In one embodiment, while cyclically performing the steps of determining rock breakthrough pressure based on online fluid saturation testing, internal images of the core under test are also incorporated, and the injection pressure difference corresponding to the water saturation and interface changes is used as the breakthrough pressure of the core under test.

[0063] Specifically, obtaining the water saturation of the test core when performing the operation of injecting non-wetting phase fluid into the test core saturated with formation water under the current cycle injection pressure difference can include: obtaining the water saturation and internal image of the test core when performing the operation of injecting non-wetting phase fluid into the test core saturated with formation water under the current cycle injection pressure difference.

[0064] Within a preset time period, when it is determined that the water saturation of the core under the current cycle injection pressure difference has not changed, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed with the next cycle injection pressure difference. This may include: within a preset time period, when it is determined that the water saturation and the interface between the non-wetting phase fluid and the wetting phase fluid has not changed under the current cycle injection pressure difference based on the water saturation and internal image of the core under the current cycle injection pressure difference, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed with the next cycle injection pressure difference.

[0065] Within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference begins to change, the cycle ends. This can include: within a preset time period, when it is determined, based on the water saturation of the core sample and internal images, that the water saturation and the interface between the non-wetting fluid and the wetting fluid under the current cycle injection pressure difference begin to change, the cycle ends.

[0066] Using the injection pressure difference corresponding to when the water saturation begins to change as the breakthrough pressure of the core sample can include: using the injection pressure difference corresponding to when the water saturation and interface begin to change as the breakthrough pressure of the core sample.

[0067] In practical implementation, embodiments of the present invention further combine internal images of the rock core with a determination of whether the interface changes based on these images to determine the rock breakthrough pressure, thereby improving accuracy and user experience. Additionally, the water saturation of the rock core mentioned in these embodiments can also refer to the water saturation of different parts of the rock core, which can further improve the measurement accuracy of the rock breakthrough pressure.

[0068] The purpose of this invention is to address the shortcomings of current methods for determining rock gas breakthrough pressure by creatively introducing high-temperature, high-pressure online fluid saturation testing technology to conduct fluid displacement experiments under formation temperature and pressure conditions. During the experiment, the online fluid saturation testing system monitors the water saturation of various parts of the core in real time. Simultaneously, two-dimensional imaging is used to obtain the interface changes between the displacing and replaced phases, efficiently and accurately determining the moment of fluid breakthrough in the rock, thus obtaining a real-time, accurate, and efficient method for determining rock breakthrough pressure.

[0069] Online fluid saturation testing technology is applicable to the analysis of physical properties of rock cores, such as porosity, permeability, water saturation, and mobile water saturation. Specific techniques include online X-ray, online CT scanning, and online nuclear magnetic resonance (NMR). One-dimensional online fluid saturation testing technology allows for quantitative analysis of water saturation at different locations. Two-dimensional online saturation imaging technology provides a direct visual representation of the pore size and fluid distribution within the rock core, obtaining a two-dimensional saturation profile and the location of the fluid interface. The step size / resolution of the two-dimensional profile in online fluid saturation testing can reach the millimeter scale, meaning the thickness of the scanned core slice can be as low as 1-2 millimeters. Therefore, during experiments, even when the injected fluid has just begun to enter the rock core, and the interface between the wetting and non-wetting phases has advanced a very small distance, it can be detected in real time using online fluid saturation testing technology. This allows for rapid and accurate identification of the process of the injected fluid breaking through the capillary pressure and entering the rock core, without having to wait for the fluid to slowly flow through the core and exit from the outlet. This technology significantly reduces the time required to wait and observe the fluid breaking through the rock core under the experimental pressure differential, and also improves testing accuracy.

[0070] To achieve the above objectives, such as Figure 2 As shown, this embodiment of the invention provides a rock breakthrough pressure measurement device based on online fluid saturation testing, which can be used in specific implementations. Figure 2The device shown implements step 8021 above. In specific implementation, this embodiment of the invention will use online nuclear magnetic resonance technology as an example. Of course, other online volume saturation testing technologies, such as online X-ray and online CT scanning, can also be used to measure breakthrough pressure. The testing device is described below.

[0071] The apparatus described in this embodiment of the invention may include an injection system (including an injection pump), a model system (including a core sample), a nuclear magnetic resonance testing system (device), a confining pressure system (including a confining pressure pump), a back pressure system (including a back pressure pump), and an outlet separation and metering system (component). The following description, in conjunction with the appendix... Figure 2 A detailed description of each part of the device is as follows:

[0072] Injection system: mainly includes a high-precision constant-speed pressure pump and a fluid intermediate container, used to provide power for fluid injection. In one embodiment, the injection pump can be a constant-speed and constant-pressure pump, which can ensure safe and stable operation of the test.

[0073] Model System: The model system mainly includes: a core model and a nuclear magnetic resonance (NMR) core holder (in order to achieve the measurement of breakthrough pressure using NMR technology, the core holder in this embodiment of the invention can be as follows). Figure 2 The NMR holder shown in the figure allows fluid to flow in the core model (the core to be tested).

[0074] Nuclear magnetic resonance testing system: mainly includes nuclear magnetic resonance spectrometer and related data processing software, used to monitor fluid saturation profile in rock cores.

[0075] The confining pressure system connects to the core holder and is supplied with the confining pressure required by the model by the confining pressure pump, which is usually 2-3 MPa higher than the displacement pressure.

[0076] Back pressure system: mainly includes back pressure valve and back pressure pump, used to control the model outlet pressure (this outlet pressure and the injection pump pressure form an injection pressure difference) to ensure that the fluid flows under the set pressure difference.

[0077] Outlet separation and metering system (outlet separation and metering components): This may include a gas-liquid separator and a flow meter, used for separating and metering the two-phase fluid at the outlet. Under breakthrough pressure, the gas-liquid mixture flows out of the core and enters the separation observation container (e.g., Figure 2 or Figure 6 The outlet metering observation container shown. Due to density differences, the gas phase is discharged from the top of the container, passing through a mass flow meter (such as...). Figure 2 or Figure 6The high-pressure mass flow monitor shown measures its flow rate, i.e., the gas output; liquid water enters the lower part of the separator, and its output liquid volume is measured through a transparent graduated container. By separating and measuring the gas-liquid mixture through the above steps, it is further confirmed that the injected fluid—carbon dioxide—has flowed through the core and is produced from the outlet, proving (verifying) that the injection pressure has reached the core's breakthrough pressure. That is, in one embodiment, the non-wetting phase fluid is a gas; as shown... Figure 6 As shown, the testing device may further include: an outlet separation metering component 9, which is located at the end of the back pressure pump 6 away from the core holder 3, for separating the gas-liquid mixture after it flows out of the core under the drive of the breakthrough pressure, and separately measuring the liquid output and gas output. Based on whether the injection pressure difference corresponding to the change in the output verification interface has reached the breakthrough pressure of the rock, the outlet separation metering scheme is used to further verify the accuracy of the breakthrough pressure measurement.

[0078] The injection system can be connected to the model system via a pressure-resistant pipeline; one end of the model system is connected to the injection system, and the other end is connected to the back pressure system and then to the separation metering system; the model system is placed inside the nuclear magnetic resonance testing system cavity to perform nuclear magnetic resonance testing in real time.

[0079] As can be seen from the above, in one embodiment, in step 8021, obtaining the water saturation of the core sample when performing the operation of injecting non-wetting phase fluid into the core sample saturated with formation water under the current periodic injection pressure differential includes obtaining the water saturation of the core sample using an online fluid saturation testing device, such as... Figure 2 As shown, the testing apparatus includes: a differential pressure generating device, a core holder 3, a confining pressure pump 4, a nuclear magnetic resonance testing device 5, and a controller 7; wherein:

[0080] Differential pressure generating device, used to provide injection differential pressure for injecting non-wetting phase fluid;

[0081] The core holder 3 is installed in the test chamber of the nuclear magnetic resonance testing device 5. It is used to place the core sample saturated with formation water and heat it to the formation temperature, and maintain the temperature at the formation temperature.

[0082] The confining pressure pump 4 is connected to the core holder 3 and is used to provide the required confining pressure to the core holder 3 as the formation pressure of the core to be tested.

[0083] Nuclear magnetic resonance testing device 5 is used to perform nuclear magnetic resonance testing on the core sample saturated with formation water to obtain the water saturation of the core sample.

[0084] The controller 7 is used to control the operation of the differential pressure generating device, core holder 3, confining pressure pump 4, and nuclear magnetic resonance testing device 5 under the formation temperature and pressure environment, so as to obtain the water saturation of the core under the current cycle injection differential when performing the operation of injecting non-wetting phase fluid into the core saturated with formation water.

[0085] In practical implementation, similarly as described in the above embodiments, when determining the rock breakthrough pressure, internal images of the rock, such as two-dimensional nuclear magnetic resonance images, can be used. The controller can also control the operation of various components to acquire internal images of the rock core to be tested. Utilizing... Figure 2 The testing apparatus shown can further improve the efficiency and accuracy of two-dimensional NMR image acquisition by implementing step 8021 described above. For a detailed description of this testing apparatus, please refer to the following embodiment. Additionally... Figure 2 The various systems can include a variety of solenoid valves. The controller can control the operation of each system by controlling the solenoid valves of each system, which will not be elaborated here.

[0086] To facilitate understanding of how this invention is implemented, the following is combined with... Figure 6 Taking the stepwise pressure displacement method as an example, this paper introduces a method for detecting rock breakthrough pressure based on online fluid saturation testing:

[0087] 1. Rock samples can be prepared according to the method described in 5.1 of standard SY / T 5748-2020, and formation water can be prepared according to the method described in 5.4 of standard SY / T5748-2020.

[0088] 2. After fully saturating the core sample with formation water, place it in a core holder (NMR holder) equipped with heating and temperature control functions to ensure the required formation temperature conditions. Connect the testing equipment (e.g., Figure 2 As shown, confining pressure fluid is injected through a confining pressure system to simulate the overlying formation pressure P of the core. H The core holder, confining pressure system, and confining pressure fluid are all made of non-magnetic, hydrogen-free, and non-metallic materials to ensure that they will not interfere with the nuclear magnetic resonance measurement process. Specifically, in one embodiment, the core holder, confining pressure pump, and confining pressure fluid are all made of non-magnetic, hydrogen-free, and non-metallic materials, which guarantees the accuracy of the test.

[0089] 3. Add liquid at the outlet end and set the outlet pressure and back pressure. The outlet pressure and back pressure should be 0.1-1.0 MPa higher than the saturated vapor pressure of formation water at the test temperature.

[0090] 4. Under formation temperature and pressure conditions, nuclear magnetic resonance (NMR) tests were performed on core samples saturated with formation water to obtain water saturation at various locations in the core and two-dimensional NMR images of the core.

[0091] 5. Prepare the injection fluid. The injection fluid is a non-wetting phase. Depending on the experimental purpose, different types of non-wetting phase fluids such as CO2, N2, or kerosene can be used. Therefore, in one embodiment, there can be multiple intermediate containers. Each intermediate container is used to store different types of non-wetting phase fluids, allowing the user to flexibly select the required fluid type. To prevent corrosion of the injection pump, the injection fluid is usually placed in an intermediate container. The non-wetting fluid is injected into the core under test by a constant-speed, constant-pressure pump that displaces the intermediate container. That is, in one embodiment, when the operation of injecting non-wetting phase fluid into a core saturated with formation water is performed under the current period injection pressure difference, the water saturation and internal image of the core under test can be obtained by: obtaining the water saturation and two-dimensional NMR images of various parts of the core under test when the operation of injecting non-wetting phase fluid into a core saturated with formation water is performed under the current period injection pressure difference using nuclear magnetic resonance (NMR) technology. Obtaining the water saturation and two-dimensional NMR images of various parts of the core under test using NMR technology can improve the testing accuracy and speed. In addition, acquiring two-dimensional NMR images can improve the efficiency of subsequent determination of breakthrough pressure.

[0092] 6. The initial differential pressure P can be set as described in section 6.4 of standard SY / T 5748-2020. i (i.e., the preset initial injection pressure difference obtained).

[0093] 7. The injection pressure difference P was observed in real time using an nuclear magnetic resonance system. i Under these conditions, the injected non-wetting phase fluid (CO2, N2, or kerosene, etc.) is used to determine whether it enters the core sample. The thickness of the core slices scanned by nuclear magnetic resonance (NMR) can be as low as 1-2 mm. In one embodiment, the thickness of the core sample is 1-2 mm, allowing for rapid determination of whether the injected fluid can overcome capillary pressure and enter the core. This means that using NMR to scan the internal image of the core allows for the use of very thin core slices, thus accelerating the experiment and further improving the efficiency of the breakthrough pressure test. Based on NMR monitoring, under a constant pressure difference P... i The waiting time (preset period) for observing and judging fluid breakthrough will be much shorter than the time interval described in 6.5 of standard SY / T 5748-2020. Once the pressure difference P is determined... i If the water saturation remains unchanged, it can be determined that the injected fluid is unlikely to overcome the capillary pressure and enter the core under test. Increasing the injection pressure differential yields the injection pressure differential for the next cycle. For example, the injection pressure can be rapidly increased to obtain the injection pressure differential for the next cycle (the next pressure differential P). i+1 Continue the experiment below.

[0094] 8. The injection pressure can be gradually increased according to the pressure intervals described in 6.6 of standard SY / T 5748-2020, and nuclear magnetic resonance (NMR) testing can be performed according to step 7 to determine the fluid entry into the core. When the NMR scan observes a change in the water saturation profile of the core and the fluid interface begins to appear, the pressure difference P is recorded. t At this point, the pressure difference P can be preliminarily determined. t That is, the core breakthrough pressure P c .

[0095] 9. To further determine the pressure difference P t Is it truly to break through the pressure P? c The pressure difference P can be maintained appropriately. t For a set period (preset holding time), the changes in core water saturation and fluid interface are continuously observed (monitored) using an NMR imaging system. If the fluid interface moves further towards the outlet and the water saturation at the inlet continues to decrease (continuously decreasing), then P can be determined. t This is the rock's breakthrough pressure P. c The experiment can be ended at this point.

[0096] As can be seen from the above, in one embodiment, the method for determining rock breakthrough pressure may further include the following steps: verifying whether the injection pressure difference corresponding to the water saturation and interface changes is the breakthrough pressure of the core sample to be tested.

[0097] During the preset holding period of the injection pressure difference corresponding to the start of water saturation and interface change, monitor whether the interface continues to move towards the outlet direction of the non-wetting phase fluid, and / or whether the water saturation at the inlet end of the core to be tested continues to decrease.

[0098] When the interface continues to move towards the outlet direction of the non-wetting phase fluid, and / or the water saturation at the inlet end of the core sample continues to decrease, the injection pressure difference corresponding to the water saturation and interface changes is determined as the breakthrough pressure of the core sample.

[0099] In practice, after the cycle ends, it can be further verified whether the injection pressure difference corresponding to when the interface begins to change is the breakthrough pressure of the core to be tested. When the interface continues to move towards the outlet direction of the non-wetting phase fluid and / or the water saturation at the inlet end of the core to be tested continues to decrease, the injection pressure difference corresponding to when the water saturation and interface begin to change is determined as the breakthrough pressure of the core to be tested, which further improves the accuracy of the breakthrough pressure test.

[0100] As can be seen from the above, in one embodiment, the method for determining rock breakthrough pressure may further include determining that the injection pressure difference corresponding to when the water saturation and interface begin to change is not the breakthrough pressure of the rock core when the interface is not detected to continue moving towards the outlet direction of the non-wetting phase fluid and / or the water saturation at the inlet end of the core to be tested does not continue to decrease.

[0101] In practice, after the cycle ends, it is possible to further verify whether the injection pressure difference corresponding to the water saturation and the interface at which changes begin to occur is the breakthrough pressure of the core under test. If the interface does not continue to move towards the outlet of the non-wetting phase fluid and / or the water saturation at the inlet of the core under test does not continue to decrease, it is determined that the injection pressure difference corresponding to the interface at which changes begins to occur is not the breakthrough pressure of the core under test, thus further improving the accuracy of the breakthrough pressure test.

[0102] Figure 3a and Figure 3b These are images of online fluid saturation tests conducted before and after the fluid penetrated the core sample, as shown in this embodiment of the invention. Figure 3a This is a two-dimensional online fluid saturation test image of a core sample when it is completely saturated with brine, as shown in this embodiment of the invention. Figure 3b This is a two-dimensional online fluid saturation test image of the core after breakthrough in an embodiment of the present invention, for comparison. Figure 3a and Figure 3b It can intuitively show the fluid interface propagation after the non-wetting phase fluid enters the core. Figure 4 The measured water saturation profiles at different locations before and after fluid penetration in this embodiment of the invention visually demonstrate the rapid decrease in water saturation at the inlet after the non-wetting phase fluid enters the core. Figure 6 In this context, an online fluid saturation testing device for determining rock breakthrough pressure may include: an injection pump 1, an intermediate container 2, a core holder 3, a confining pressure pump 4, a nuclear magnetic resonance (NMR) testing device 5, a back pressure pump 6, an outlet separation and metering component 9, and a controller 7. The controller controls the injection pump 1, intermediate container 2, core holder 3, confining pressure pump 4, NMR testing device 5, back pressure pump 6, and outlet separation and metering component 9 to operate in multiple cycles to acquire the water saturation and internal images of various parts of the core under each injection pressure differential cycle. Figure 6 As shown, the water saturation and internal images of various parts of the core under each injection pressure differential cycle are transmitted to [the relevant authority / system]. Figure 6 The device 8 for determining rock breakthrough pressure performs the method for determining rock breakthrough pressure as described above, and finally determines the rock breakthrough pressure.

[0103] In summary, the features and advantages of the embodiments of this invention are as follows: This invention provides an accurate and rapid method for measuring rock breakthrough pressure under formation conditions (high temperature and high pressure). By creatively introducing online fluid saturation testing technology, the pressure and time at which injected fluid begins to enter the core and replace formation water can be accurately and quickly determined, greatly shortening the rock breakthrough pressure testing time and improving testing accuracy. Therefore, the embodiments of this invention are of great significance for evaluating caprock sealing, determining the enrichment capacity of oil and gas fields, and assessing the safety of carbon dioxide geological sequestration.

[0104] This invention also provides an online fluid saturation test control method for determining rock breakthrough pressure, as described in the following embodiments. Since the principle behind this control method is similar to the method for determining rock breakthrough pressure described above, the implementation of this control method can refer to the implementation of the method for determining rock breakthrough pressure described above; repeated details will not be elaborated further.

[0105] Figure 7 This is a flowchart illustrating the online fluid saturation test control method for determining rock breakthrough pressure in an embodiment of the present invention, as shown below. Figure 7 As shown, the control method includes the following steps:

[0106] Step 701: Control the core holder to heat to the preset formation temperature and maintain it at the formation temperature; the core holder contains a core sample saturated with formation water and is placed inside the test chamber of the nuclear magnetic resonance testing device;

[0107] Step 702: When the core holder is monitored to be kept at the formation temperature, the confining pressure pump is controlled to provide the required confining pressure to the core holder by injecting fluid as the formation pressure of the core to be tested;

[0108] Step 703: Under the aforementioned formation temperature and formation pressure, control the nuclear magnetic resonance testing device to perform nuclear magnetic resonance testing on the core sample saturated with formation water;

[0109] Step 704: Control the differential pressure generating device to obtain the water saturation of the test core when performing the operation of injecting non-wetting phase fluid into the test core saturated with formation water under different periodic injection differential pressures.

[0110] In one embodiment, the water saturation of the core under different periodic injection pressure differences is used to: cyclically determine whether the water saturation under different periodic injection pressure differences begins to change within a preset time period, and use the injection pressure difference corresponding to when the water saturation begins to change as the breakthrough pressure of the core under test.

[0111] In one embodiment, the water saturation of the core sample under different periodic injection pressure differentials is used to: determine whether the water saturation and internal image have changed under the current periodic injection pressure differential; within a preset time period, when it is determined, based on the water saturation and internal image of the core sample, that the water saturation and the interface between the non-wetting fluid and the wetting fluid under the current periodic injection pressure differential remain unchanged, the injection pressure differential is increased to obtain the injection pressure differential for the next period, and the next cycle operation is performed using the next periodic injection pressure differential; within a preset time period, when it is determined, based on the water saturation and internal image of the core sample, that the water saturation and the interface between the non-wetting fluid and the wetting fluid under the current periodic injection pressure differential begin to change, the cycle ends; the injection pressure differential corresponding to when the water saturation and interface begin to change is taken as the breakthrough pressure of the core sample.

[0112] This invention also provides an apparatus for determining rock breakthrough pressure, as described in the following embodiments. Since the principle of the apparatus for determining rock breakthrough pressure is similar to the method for determining rock breakthrough pressure described above, the implementation of this apparatus for determining rock breakthrough pressure can refer to the implementation of the method for determining rock breakthrough pressure described above, and will not be repeated here.

[0113] Figure 5 This is a schematic diagram of the device for determining rock breakthrough pressure in an embodiment of the present invention, as shown below. Figure 5 As shown, the device includes:

[0114] Acquisition unit 81 is used to acquire the preset initial injection differential pressure;

[0115] The loop unit 82 is used to repeatedly execute the following steps based on online fluid saturation testing to determine the rock breakthrough pressure, with a preset initial injection pressure differential as the initial value. The following operations are performed in each loop cycle:

[0116] The water saturation of the test core is obtained when the operation of injecting non-wetting phase fluid into the test core saturated with formation water is performed under the current cycle injection pressure differential; the test core is under formation temperature and pressure environment;

[0117] Within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference does not change, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed with the next cycle injection pressure difference.

[0118] Within a preset time period, the cycle ends when the water saturation of the core sample begins to change under the current cycle injection pressure differential.

[0119] Unit 83 is used to determine the injection pressure difference corresponding to the start of change in water saturation as the breakthrough pressure of the core sample to be tested.

[0120] In one embodiment, the loop unit is specifically used for:

[0121] When performing the operation of injecting non-wetting phase fluid into a core sample saturated with formation water under the current cycle injection pressure differential, obtain the water saturation and internal image of the core sample.

[0122] Within a preset time period, when it is determined, based on the water saturation and internal image of the core sample, that there is no change in the water saturation and the interface between the non-wetting fluid and the wetting fluid under the current cycle injection pressure difference, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed using the next cycle injection pressure difference.

[0123] Within a preset time period, when the water saturation and the interface between the non-wetting fluid and the wetting fluid begin to change under the current injection pressure differential, based on the water saturation and internal images of the core sample, the cycle ends.

[0124] The determining unit is specifically used to: take the injection pressure difference corresponding to the water saturation and the interface when they begin to change as the breakthrough pressure of the core sample to be tested.

[0125] In specific implementation, embodiments of the present invention further combine internal images of the rock core with the determination of rock breakthrough pressure based on whether the interface changes according to the image, thereby further improving accuracy and user experience.

[0126] This invention also provides an online fluid saturation testing device for determining rock breakthrough pressure, as described in the following embodiments. Since the principle behind this testing device is similar to the method for determining rock breakthrough pressure described above, the implementation of this testing device can refer to the implementation of the method for determining rock breakthrough pressure described above; repeated details will not be elaborated further.

[0127] Figure 2 This is a schematic diagram of the online fluid saturation testing device for determining rock breakthrough pressure in an embodiment of the present invention, as shown below. Figure 2 As shown, the testing apparatus includes: a differential pressure generating device, a core holder 3, a confining pressure pump 4, a nuclear magnetic resonance testing device 5, and a controller 7; wherein:

[0128] Differential pressure generating device, used to provide injection differential pressure for injecting non-wetting phase fluid;

[0129] The core holder 3 is installed in the test chamber of the nuclear magnetic resonance testing device 5. It is used to place the core sample saturated with formation water and heat it to the formation temperature, and maintain the temperature at the formation temperature.

[0130] The confining pressure pump 4 is connected to the core holder 3 and is used to provide the required confining pressure to the core holder 3 as the formation pressure of the core to be tested.

[0131] Nuclear magnetic resonance testing device 5 is used to perform nuclear magnetic resonance testing on the core sample saturated with formation water to obtain the water saturation of the core sample.

[0132] The controller 7 is used to control the operation of the differential pressure generating device, core holder 3, confining pressure pump 4, and nuclear magnetic resonance testing device 5 under the formation temperature and pressure environment, so as to obtain the water saturation of the core under different periodic injection differentials when performing the operation of injecting non-wetting phase fluid into the core saturated with formation water.

[0133] In one embodiment, the water saturation of the core under different periodic injection pressure differences is used to: cyclically determine whether the water saturation under different periodic injection pressure differences begins to change within a preset time period, and use the injection pressure difference corresponding to when the water saturation begins to change as the breakthrough pressure of the core under test.

[0134] In one embodiment, the differential pressure generating device may include:

[0135] Injection pump 1 is used to provide injection pressure for injecting non-wetting phase fluid;

[0136] The back pressure pump 6 is located at the second end of the core holder 3. It is used to control the outlet pressure of the core to be tested to reach the preset back pressure, so as to ensure that the fluid flows under the injection pressure difference formed by the injection pressure and the back pressure.

[0137] In one embodiment, the above-mentioned testing apparatus may further include:

[0138] Intermediate container 2 is used to pre-store non-wetting phase fluid. One end of intermediate container 2 is connected to injection pump 1, and the other end of intermediate container 2 is connected to the first end of core holder 3.

[0139] In one embodiment, the number of intermediate containers is multiple; each intermediate container is used to store different types of non-wetting phase fluids.

[0140] In one embodiment, the water saturation of the core under the current cycle injection pressure differential is specifically used for: determining whether the water saturation and internal image have changed under the current cycle injection pressure differential; within a preset time period, when it is determined, based on the water saturation and internal image of the core under the current cycle injection pressure differential, that the water saturation and the interface between the non-wetting fluid and the wetting fluid have not changed, the injection pressure differential is increased to obtain the injection pressure differential for the next cycle, and the next cycle operation is performed using the next cycle injection pressure differential; within a preset time period, when it is determined, based on the water saturation and internal image of the core under the current cycle injection pressure differential, that the water saturation and the interface between the non-wetting fluid and the wetting fluid begin to change, the cycle ends; the injection pressure differential corresponding to when the water saturation and interface begin to change is taken as the breakthrough pressure of the core under the current cycle.

[0141] In one embodiment, the core holder, confining pressure pump, and confining pressure fluid are all non-magnetic, hydrogen-free, and non-metallic materials.

[0142] In one embodiment, the thickness of the core sample is in the range of 1 to 2 millimeters.

[0143] In one embodiment, the non-wetting phase fluid is a gas; such as Figure 6 As shown, the experimental apparatus may further include: an outlet separation metering component 9, which is located at the end of the back pressure pump 6 away from the core holder 3, for separating the gas-liquid mixture after it flows out of the core under the drive of the breakthrough pressure, measuring the liquid output and gas output respectively, and verifying whether the injection pressure difference corresponding to the change in water saturation has reached the breakthrough pressure of the rock based on the output.

[0144] In one embodiment, the injection pump is a constant speed and constant pressure pump.

[0145] The controller is specifically used to control the operation of the differential pressure generating device, core holder 3, confining pressure pump 4, and nuclear magnetic resonance testing device 5 under the formation temperature and pressure environment, so as to obtain the water saturation of the core under different periodic injection pressure differentials when performing the operation of injecting non-wetting phase fluid into the core saturated with formation water. The water saturation of the core under different periodic injection pressure differentials is used for: determining whether the water saturation changes under the current periodic injection pressure differential; within a preset time period, if it is determined that the water saturation of the core under the current periodic injection pressure differential has not changed, increasing the injection pressure differential to obtain the next periodic injection pressure differential, and performing the next cycle operation with the next periodic injection pressure differential; within a preset time period, if it is determined that the water saturation of the core under the current periodic injection pressure differential begins to change, ending the cycle; and using the injection pressure differential corresponding to the point where the water saturation begins to change as the breakthrough pressure of the core under test.

[0146] This invention also provides an online fluid saturation test controller for determining rock breakthrough pressure, as described in the following embodiments. Since the principle behind this controller's problem-solving is similar to the method for determining rock breakthrough pressure described above, its implementation can refer to the implementation of the method for determining rock breakthrough pressure described above; repeated details will not be elaborated further.

[0147] Figure 8 This is a schematic diagram of the structure of the online fluid saturation test controller for determining rock breakthrough pressure in an embodiment of the present invention, as shown below. Figure 8 As shown, the controller includes:

[0148] The first control unit 71 is used to control the core holder to heat to a preset formation temperature and maintain it at the formation temperature; the core holder contains a core sample saturated with formation water and is set inside the test chamber of the nuclear magnetic resonance testing device.

[0149] The second control unit 72 is used to control the confining pressure pump to provide the required confining pressure to the core holder as the formation pressure of the core to be tested by injecting fluid when the core holder is kept at a constant temperature of the formation.

[0150] The third control unit 73 is used to control the nuclear magnetic resonance testing device to perform nuclear magnetic resonance testing on the core sample saturated with formation water under the formation temperature and formation pressure.

[0151] The fourth control unit 74 is used to control the water saturation of the test core when the pressure difference generating device obtains the water saturation of the test core during the operation of injecting non-wetting phase fluid into the test core saturated with formation water under different periodic injection pressure differences.

[0152] In one embodiment, the water saturation of the core under different periodic injection pressure differences is used to: cyclically determine whether the water saturation under different periodic injection pressure differences begins to change within a preset time period, and use the injection pressure difference corresponding to when the water saturation begins to change as the breakthrough pressure of the core under test.

[0153] In one embodiment, the water saturation of the core under different periodic injection pressure differentials is specifically used for: determining whether the water saturation and internal image of the core under the current periodic injection pressure differential have changed; within a preset time period, when it is determined, based on the water saturation and internal image of the core under the current periodic injection pressure differential, that the water saturation and the interface between the non-wetting phase fluid and the wetting phase fluid have not changed, the injection pressure differential is increased to obtain the injection pressure differential for the next period, and the next cycle operation is performed using the next cycle injection pressure differential; within a preset time period, when it is determined, based on the water saturation and internal image of the core under the current periodic injection pressure differential, that the water saturation and the interface between the non-wetting phase fluid and the wetting phase fluid begin to change, the cycle ends; the injection pressure differential corresponding to when the water saturation and interface begin to change is taken as the breakthrough pressure of the core under the current periodic injection pressure differential.

[0154] This invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described method for determining rock breakthrough pressure and the online fluid saturation test control method.

[0155] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for determining rock breakthrough pressure and the online fluid saturation test control method.

[0156] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for determining rock breakthrough pressure and the online fluid saturation test control method.

[0157] Compared to existing technologies where fluid flow is allowed to break through the core during pressure testing, resulting in extremely low flow rates and volumes, and where the core used for pressure testing is often quite long to overcome end-face effects, making it difficult to accurately determine whether fluid has broken through under a set pressure, the present invention provides a superior solution for determining rock breakthrough pressure. This solution is time-consuming, often lasting a week or several weeks, making it difficult to balance accuracy and efficiency. The online fluid saturation test allows for real-time detection of even small steps at the interface between the wetting and non-wetting phases, even as the injected fluid just begins to enter the core. This enables rapid and accurate identification of the process where the injected fluid breaks through capillary pressure into the core, without waiting for the fluid to slowly flow through the core and exit from the outlet. Therefore, this invention can efficiently and accurately determine rock breakthrough pressure based on online fluid saturation testing, which is significant for evaluating caprock sealing, assessing oil and gas field enrichment capacity, and assessing the safety of carbon dioxide geological storage.

[0158] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0159] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems, and computer program products) according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0160] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0161] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0162] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An online fluid saturation testing device for determining rock breakthrough pressure, characterized in that, include: Differential pressure generating device, core holder (3), confining pressure pump (4), nuclear magnetic resonance testing device (5), and controller (7); wherein: Differential pressure generating device, used to provide injection differential pressure for injecting non-wetting phase fluid; The core holder (3) is set in the test chamber of the nuclear magnetic resonance test device (5) to hold the core to be tested saturated with formation water and heat it to the formation temperature and keep it constant at the formation temperature. A confining pressure pump (4) is connected to a core holder (3) to provide the core holder (3) with the required confining pressure as the formation pressure of the core to be tested; Nuclear magnetic resonance testing device (5) is used to perform nuclear magnetic resonance testing on the core sample of the test sample saturated with formation water to obtain the water saturation of the core sample. The controller (7) is used to control the operation of the differential pressure generating device, core holder (3), confining pressure pump (4), and nuclear magnetic resonance testing device (5) under the formation temperature and pressure environment, so as to obtain the water saturation of the core under different periodic injection differentials when performing the operation of injecting non-wetting phase fluid into the core saturated with formation water.

2. The apparatus as claimed in claim 1, characterized in that, The water saturation of the core sample under different periodic injection pressure differentials is used to: determine whether the water saturation under different periodic injection pressure differentials begins to change within a preset time period, and take the injection pressure differential corresponding to when the water saturation begins to change as the breakthrough pressure of the core sample.

3. The apparatus as described in claim 1, characterized in that, The differential pressure generating device includes: An injection pump (1) is used to provide injection pressure for injecting non-wetting phase fluid; The back pressure pump (6) is set at the second end of the core holder (3) to control the outlet pressure of the core to be tested to reach the preset back pressure pressure, so as to ensure that the fluid flows under the injection pressure difference formed by the injection pressure and the back pressure.

4. The apparatus as described in claim 3, characterized in that, The injection pump is a constant speed and constant pressure pump.

5. The apparatus as described in claim 3, characterized in that, The non-wetting phase fluid is gas; the device further includes: an outlet separation metering component (9), which is located at the end of the back pressure pump (6) away from the core holder (3), and is used to separate the gas-liquid mixture after it flows out of the core under the drive of the breakthrough pressure, to measure the liquid output and gas output respectively, and to verify whether the injection pressure difference corresponding to the change in water saturation has reached the breakthrough pressure of the rock based on the output.

6. The apparatus as claimed in claim 3, characterized in that, Also includes: The intermediate container (2) is used to pre-store the non-wetting phase fluid. One end of the intermediate container (2) is connected to the injection pump (1), and the other end of the intermediate container (2) is connected to the first end of the core holder (3).

7. The apparatus as claimed in claim 6, characterized in that, The number of intermediate containers is multiple; each intermediate container is used to store different types of non-wetting phase fluids.

8. The apparatus as claimed in claim 1, characterized in that, The core holder, confining pressure pump, and confining pressure fluid are all made of non-magnetic, hydrogen-free, non-metallic materials.

9. A device for determining rock breakthrough pressure, characterized in that, include: The acquisition unit is used to acquire the preset initial injection differential pressure. The cyclic unit, using a preset initial injection differential pressure as the initial value, repeatedly executes the following steps for determining the rock breakthrough pressure based on online fluid saturation testing. Each cycle performs the following operations: The water saturation of the test core is obtained when the operation of injecting non-wetting phase fluid into the test core saturated with formation water is performed under the current cycle injection pressure differential; the test core is under formation temperature and pressure environment; Within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference does not change, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed with the next cycle injection pressure difference. Within a preset time period, the cycle ends when the water saturation of the core sample begins to change under the current cycle injection pressure differential. The unit is defined as the injection pressure difference corresponding to the point when the water saturation begins to change, which is used as the breakthrough pressure of the core sample to be tested.

10. An online fluid saturation test controller for determining rock breakthrough pressure, characterized in that, include: The first control unit is used to control the core holder to heat to a preset formation temperature and maintain it at the formation temperature; the core holder contains a core sample saturated with formation water and is set inside the test chamber of the nuclear magnetic resonance testing device. The second control unit is used to control the confining pressure pump to provide the required confining pressure to the core holder as the formation pressure of the core to be tested by injecting fluid when the core holder is kept at a constant temperature of the formation. The third control unit is used to control the nuclear magnetic resonance testing device to perform nuclear magnetic resonance testing on the core sample saturated with formation water under the formation temperature and formation pressure. The fourth control unit is used to control the water saturation of the test core when the pressure difference generating device obtains the water saturation of the test core during the operation of injecting non-wetting phase fluid into the test core saturated with formation water under different periodic injection pressure differences.

11. The controller as claimed in claim 10, characterized in that, The water saturation of the core sample under different periodic injection pressure differentials is used to: determine whether the water saturation under different periodic injection pressure differentials begins to change within a preset time period, and take the injection pressure differential corresponding to when the water saturation begins to change as the breakthrough pressure of the core sample.

12. A method for determining rock breakthrough pressure, characterized in that, include: Obtain the preset initial injection differential pressure; Using a preset initial injection pressure differential as the initial value, the following steps for determining the rock breakthrough pressure based on online fluid saturation testing are executed cyclically, with the following operations performed in each cycle: The water saturation of the test core is obtained when the operation of injecting non-wetting phase fluid into the test core saturated with formation water is performed under the current cycle injection pressure differential; the test core is under formation temperature and pressure environment; Within a preset time period, when it is determined that the water saturation of the core sample under the current cycle injection pressure difference does not change, the injection pressure difference is increased to obtain the injection pressure difference for the next cycle, and the next cycle operation is performed with the next cycle injection pressure difference. Within a preset time period, the cycle ends when the water saturation of the core sample begins to change under the current cycle injection pressure differential. The injection pressure difference corresponding to when the water saturation begins to change is taken as the breakthrough pressure of the core sample to be tested.

13. The method as described in claim 12, characterized in that, When performing the following steps to determine the rock breakthrough pressure based on online fluid saturation testing, the internal images of the rock core to be tested were also combined, and the injection pressure difference corresponding to the water saturation and interface changes was used as the breakthrough pressure of the rock core to be tested.

14. The method as described in claim 13, characterized in that, It also includes the following steps to verify whether the injection pressure difference corresponding to the water saturation and the start of interface changes is the breakthrough pressure of the core sample: During the preset holding period of the injection pressure difference corresponding to the start of water saturation and interface change, monitor whether the interface continues to move towards the outlet direction of the non-wetting phase fluid, and / or whether the water saturation at the inlet end of the core to be tested continues to decrease. When the interface continues to move towards the outlet direction of the non-wetting phase fluid, and / or the water saturation at the inlet end of the core sample continues to decrease, the injection pressure difference corresponding to the water saturation and interface changes is determined as the breakthrough pressure of the core sample.

15. The method as described in claim 14, characterized in that, Also includes: If the interface does not continue to move towards the outlet of the non-wetting phase fluid and / or the water saturation at the inlet of the core does not continue to decrease, it is determined that the injection pressure difference corresponding to when the water saturation and interface begin to change is not the breakthrough pressure of the core.

16. The method as described in claim 12, characterized in that, To obtain the water saturation of the core sample when performing the operation of injecting non-wetting phase fluid into saturated formation water under the current cycle injection pressure differential, including: obtaining the water saturation of the core sample when performing the operation of injecting non-wetting phase fluid into saturated formation water under the current cycle injection pressure differential using nuclear magnetic resonance technology.

17. The method as described in claim 12, characterized in that, To obtain the water saturation of the test core when performing the operation of injecting non-wetting phase fluid into the test core saturated with formation water under the current periodic injection pressure differential, the method includes obtaining the water saturation of the test core using an online fluid saturation testing device, the device comprising: a pressure differential generating device, a core holder (3), a confining pressure pump (4), a nuclear magnetic resonance testing device (5), and a controller (7); wherein: Differential pressure generating device, used to provide injection differential pressure for injecting non-wetting phase fluid; The core holder (3) is set in the test chamber of the nuclear magnetic resonance test device (5) to hold the core to be tested saturated with formation water and heat it to the formation temperature and keep it constant at the formation temperature. A confining pressure pump (4) is connected to a core holder (3) to provide the core holder (3) with the required confining pressure as the formation pressure of the core to be tested; Nuclear magnetic resonance testing device (5) is used to perform nuclear magnetic resonance testing on the core sample of the test sample saturated with formation water to obtain the water saturation of the core sample. The controller (7) is used to control the operation of the differential pressure generating device, core holder (3), confining pressure pump (4), and nuclear magnetic resonance testing device (5) under the formation temperature and pressure environment, so as to obtain the water saturation of the core under test when the operation of injecting non-wetting phase fluid into the core under test saturated with formation water is performed under the current cycle injection differential.

18. A method for online fluid saturation testing and control to determine rock breakthrough pressure, characterized in that, include: The core holder is heated to a preset formation temperature and maintained at that temperature. The core holder contains a core sample saturated with formation water and is placed inside the test chamber of the nuclear magnetic resonance testing device. When the core holder is kept at a constant temperature at the formation temperature, the confining pressure pump is controlled to provide the required confining pressure to the core holder by injecting fluid as the formation pressure of the core to be tested. Under the aforementioned formation temperature and pressure, the nuclear magnetic resonance testing device is controlled to perform nuclear magnetic resonance testing on the core sample saturated with formation water. The water saturation of the test core was measured when the non-wetting phase fluid was injected into the test core saturated with formation water under different periodic injection pressure differentials by the control pressure differential generation device.

19. The method as described in claim 18, characterized in that, The water saturation of the core sample under different periodic injection pressure differentials is used to: determine whether the water saturation under different periodic injection pressure differentials begins to change within a preset time period, and take the injection pressure differential corresponding to when the water saturation begins to change as the breakthrough pressure of the core sample.

20. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method of any one of claims 12 to 19.

21. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method of any one of claims 12 to 19.

22. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method of any one of claims 12 to 19.

Images