A real-time monitoring downhole high-pressure physical property sampling system and method

Abstract

The present invention discloses a downhole high-pressure physical property sampling system and method for real-time monitoring. The sampling system includes a downhole sampling device, which includes a high-pressure physical property sampler, a sampling control short section, a density meter, a water holdup meter, a thermometer and / or a pressure gauge connected in sequence; a transmission short section, which is electrically connected to the downhole sampling device and is used to collect data collected by the density meter, water holdup meter, temperature and / or pressure gauge; a ground data processing and control system, which is electrically connected to the transmission short section, receives the data transmitted by the transmission short section, and determines whether the sampling conditions are met based on the downhole pressure, temperature, water holdup and density; if the sampling conditions are met, a sampling command is issued; wherein the transmission short section receives the sampling command and transmits the sampling command to the sampling control short section, and the sampling control short section triggers the high-pressure physical property sampler.

Description

Technical Field

[0001] The present invention belongs to the technical field of downhole high-pressure physical property sampling, and in particular relates to a downhole high-pressure physical property sampling system and method for real-time monitoring. Background Art

[0002] Obtaining downhole high-pressure physical property samples (oil, gas, or water) can represent the fluid characteristics under reservoir conditions. Laboratory analysis of these samples allows us to determine high-pressure physical property parameters (such as Bo, μo, Rs, and Co) under reservoir conditions. This provides a basis for oil and gas field evaluation, development program formulation, recovery factor prediction, and production equipment selection, design, and manufacturing, providing a foundation for oil and gas field evaluation and development / management.

[0003] At present, downhole high-pressure physical property sampling at home and abroad is carried out by steel wire conveying into the well (mechanical clock control, electronic clock control) to obtain downhole high-pressure physical property samples (oil, gas or water samples).

[0004] Because operation time is uncontrollable, to avoid unqualified samples when the instrument has not reached the desired depth or when the flow pressure has not yet stabilized, the clock preset time is often increased, reducing operation efficiency. Furthermore, since the surface cannot accurately obtain the flow pressure and fluid phase ratio—that is, information on whether the downhole fluid is in a single phase, two phases, or a three-phase oil-gas-water state—during sampling, due to the inability to monitor downhole well conditions and sample phase ratios, downhole samples often fail due to high water content or non-single-phase oil and gas, resulting in a low sampling success rate. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a real-time monitoring downhole high-pressure physical property sampling system that can monitor the state of the downhole fluid in real time and control the triggering of the downhole sampler according to the downhole fluid state to obtain qualified downhole oil, gas and water samples.

[0006] The present invention also provides a real-time monitoring downhole high-pressure physical property sampling method, which determines whether the sampling conditions are met based on the real-time downhole fluid pressure and water content, which can further improve the reliability of the judgment results and increase the success rate of obtaining qualified samples.

[0007] The technical solution provided by the present invention is:

[0008] A downhole high-pressure physical property sampling system and method for real-time monitoring, comprising:

[0009] A downhole sampling device, comprising a high-pressure physical property sampler, a sampling control nipple, a density meter, a water holdup meter, a thermometer, and a pressure gauge connected in sequence;

[0010] a transmission nipple electrically connected to the downhole sampling device and used to collect data collected by the density meter, water holdup meter, thermometer and pressure gauge;

[0011] a surface data processing and control system electrically connected to the transmission sub, receiving data transmitted by the transmission sub, and determining whether sampling conditions are met based on downhole pressure, temperature, water holdup, and density; and issuing a sampling command if the sampling conditions are met;

[0012] The transmission short section receives the sampling command and transmits the sampling command to the sampling control short section, and the sampling control short section triggers the high-pressure physical property sampler.

[0013] Preferably, the ground data processing and control system includes a moisture content calculation module and a real-time imaging module;

[0014] The water content calculation module calculates the water content of the downhole fluid in real time; and the real-time imaging module generates a water content curve graph according to the water content of the downhole fluid.

[0015] Preferably, the transmission sub collects data collected by the density meter, water holdup meter, thermometer and pressure gauge through Tbus.

[0016] Preferably, the transmission sub transmits data to the ground data processing and control system via a WSCbus bus.

[0017] A downhole high-pressure physical property sampling method for real-time monitoring, using the downhole high-pressure physical property sampling system for real-time monitoring, is characterized by comprising:

[0018] Collect density, water holdup, temperature and pressure of downhole fluid;

[0019] Determining whether the pressure of the downhole fluid is stable and higher than the bubble point pressure;

[0020] Calculating the water content of the downhole fluid and determining whether the water content of the downhole fluid meets the sampling requirements;

[0021] If the pressure of the downhole fluid is stable and higher than the bubble point pressure, and the water content of the downhole fluid meets the sampling requirements, the high-pressure physical property sampler is controlled to start sampling.

[0022] Preferably, when the pressure of the downhole fluid satisfies: P wf >P b +1.0, and the pressure variation of three adjacent sampling points does not exceed 0.05%, then the downhole fluid pressure is judged to be stable and higher than the bubble point pressure;

[0023] Among them, P wf Indicates the pressure of the downhole fluid, Pb Indicates the bubble point pressure in MPa.

[0024] Preferably, the time interval between adjacent sampling points is set to 15 minutes.

[0025] Preferably, the water content of the downhole fluid is calculated by the following formula:

[0026]

[0027] Among them, Y w Indicates moisture content, percentage; Y w-c Indicates the moisture content value obtained by water holdup, Y w-ρ Indicates the moisture content value obtained from density; C o Indicates the ground reading of the water holdup meter when the fluid oil content is 100%; C w Indicates the ground reading of the water holdup meter when the fluid water content is 100%; C m Indicates the water holdup meter reading under downhole pressure and temperature conditions; ρ m Indicates the actual measured density value of the densitometer, ρ o Indicates the density of oil under downhole pressure and temperature conditions, ρ w Indicates the density of water under downhole pressure and temperature conditions.

[0028] Preferably, if the water content of the downhole fluid is less than 5%, it is determined that the water content of the downhole fluid meets the sampling requirement.

[0029] The beneficial effects of the present invention are:

[0030] The real-time monitoring downhole high-pressure physical property sampling system provided by the present invention can achieve real-time imaging on the ground and real-time control triggering of the downhole sampler on the ground, thereby obtaining qualified downhole oil, gas and water samples.

[0031] The real-time monitoring downhole high-pressure physical property sampling method provided by the present invention monitors the downhole flow pressure to determine in real time whether the flow pressure is higher than the bubble point pressure and whether the flow is stable; calculates the water cut in real time on the ground to accurately determine the downhole fluid phase ratio; and controls the downhole trigger device in real time on the ground to obtain qualified downhole oil, gas and water samples. The method is suitable for obtaining downhole oil, gas and water samples in oil and gas field exploration and development, production wells or other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic structural diagram of the downhole sampling device described in the present invention.

[0033] Figure 2 This is a schematic diagram of the downhole sampling device with an addressing function module according to the present invention. DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0035] The present invention provides a downhole high-pressure physical property sampling system and method for real-time monitoring.

[0036] The real-time monitoring downhole high-pressure physical property sampling system includes: downhole instruments (downhole sampling devices), transmission short sections and ground data processing and control systems. Figure 1 As shown, the downhole instrument includes: a high-pressure physical property sampler, a sampling control nipple, a density meter, a water holdup meter, a temperature and pressure gauge.

[0037] The transmission sub is electrically connected to the high-pressure sampler to collect downhole fluid state data collected in real time by downhole thermometers, pressure gauges, water holdup meters and density meters.

[0038] The surface data processing and control system is electrically connected to the transmission sub, receives data transmitted by the transmission sub, and determines whether the downhole fluid meets sampling conditions based on downhole pressure, temperature, water holdup, and density. If the conditions are met, a sampling command is issued. Simultaneously, the transmission sub receives the sampling command and transmits it to the sampling control sub in the downhole instrument. The sampling control sub triggers the high-pressure physical property sampler to initiate sampling.

[0039] The transmission sub collects downhole fluid status data collected in real time by downhole thermometers, pressure gauges, water holdup meters, and densitometers via the Tbus, and transmits this data to the surface data processing and control system via the WSCbus. The surface data processing and control system includes logging and acquisition software and real-time imaging software. The logging software determines the true state of the downhole fluid based on the data collected by the transmission sub. The real-time imaging software creates real-time images of this fluid state, which can be displayed on a monitor. When the downhole production conditions meet the sampling requirements, the surface data processing and control system issues a sampling command in real time to the transmission sub. The transmission sub then forwards the sampling command to the sampling control sub. Upon receiving the command, the sampling control sub promptly initiates sampling and monitors the sampling status.

[0040] In one embodiment, the temperature, pressure, water holding capacity and density instruments are SPARTEK instruments, which are connected to the instrument bus and communicate with the telemeter through the 485 bus; the sampling controller is also connected to the instrument bus and also communicates with the telemeter through the 485 bus to upload the instrument status. When a sampling instruction is received, a current output of -100mA is generated to drive the sampler to complete the sampling.

[0041] Among them, the real-time imaging software can play back the original logging curve in real time, and can also display the logging results map. By using the platform's template technology, drawing templates with different needs can be customized to display the graphics required by the user and customize the display scale. The graphics can be directly output to the plotter or output to a graphic file in the form of a BMP bitmap.

[0042] In another embodiment, the surface data processing and control system is connected to multiple downhole instruments through a transmission sub, and simultaneously monitors and controls the multiple downhole instruments in real time.

[0043] Tbus is a downhole instrument bus. Any instrument that meets the bus standard can be connected simultaneously. Each instrument has a different address. The transmission short section identifies all instruments by address and collects data from each instrument.

[0044] Based on the needs of the mine, multiple parameters can be measured during a single trip downhole, sampling, and production logging. This allows for the acquisition of production logging profiles, layered output contributions, and the identification of water-producing zones. This allows for the avoidance of water-producing zones and the acquisition of qualified downhole oil and gas samples.

[0045] The original sampler is a mechanical sampling method with low efficiency and poor controllability. Figure 2 As shown in the figure, in one embodiment, an addressing function module is added to the mechanical function. The sampling control sub, like other logging instruments, has a unique address ID. The surface acquisition system identifies each instrument sub by the address ID. When one-touch sampling is required, a sampling command is sent to the target address. After receiving the command, the sampling sub drives the mechanical sampling device through the electromagnetic control module to perform the sampling action and return the sampling results.

[0046] The implementation process of the real-time monitoring downhole high-pressure physical property sampling method is as follows:

[0047] A surface winch lowers downhole instruments (downhole sampling devices) via a cable to the desired depth, and the well is then flowed. During this time, the surface data processing and control system records downhole pressure / temperature, water holdup, and density data, calculates the downhole fluid phase ratio, and plots a water cut curve.

[0048] At the same time, the ground data processing and control system determines whether the current downhole fluid state meets the sampling conditions. If it is determined that the sampling conditions are met, the ground data processing and control system sends a sampling command to the transmission short section in real time. The sampling control short section triggers the sampler device to obtain qualified downhole high-pressure physical property samples.

[0049] Determining sampling conditions includes determining whether the downhole fluid pressure is stable and above the bubble point pressure, and determining whether the water content of the downhole fluid meets sampling requirements. If the downhole fluid pressure is stable and above the bubble point pressure, and the water content of the downhole fluid meets the sampling requirements, the high-pressure physical property sampler is controlled to begin sampling.

[0050] (1) determining whether the pressure of the downhole fluid is stable and higher than the bubble point pressure;

[0051] The pressure of the first batch of bubbles separated from the liquid phase at a constant temperature, or the temperature of the first batch of bubbles separated from the liquid phase at a constant pressure. (During well production, field personnel control the well's production by adjusting the nozzle opening, thereby affecting the downhole pressure. During a short period of well operation, the downhole flow temperature is generally stable.) Field personnel often refer to the bubble point pressure as the saturation pressure, which is the pressure at which the hydrocarbon system reaches its bubble point. (During reservoir development, the reservoir pressure should be maintained above the bubble point pressure to avoid natural gas precipitation. This is because natural gas precipitation in the reservoir consumes energy, increases resistance, increases the viscosity of the underground crude oil, and reduces the oil recovery rate.) Before sampling, the bubble point pressure of the test layer should be calculated using an empirical formula or referenced from high-pressure physical property test data from the adjacent well.

[0052] If the downhole fluid pressure satisfies: P wf >P b +1.0, and the pressure variation of three adjacent sampling points does not exceed 0.05%, then it is judged that the pressure of the downhole fluid is stable and higher than the bubble point pressure.

[0053] Among them, P wf Indicates the pressure of the downhole fluid, P b Indicates the bubble point pressure in MPa.

[0054] As a preference, the time interval between adjacent sampling points is set to 15 minutes.

[0055] (2) Calculate the water content of downhole fluids and display the water content curve in real time through surface computers;

[0056] The water content of downhole fluid can be calculated by the water holdup or density of the fluid.

[0057] As a preference, in this embodiment, the water content of the fluid is calculated respectively by the water holdup and density of the fluid, and then the calculation results obtained by the two calculation methods are combined to obtain the final water content of the fluid.

[0058] The specific calculation method is as follows:

[0059] The water content of the fluid is calculated by formula (1) and formula (2) respectively:

[0060]

[0061]

[0062] If Y w-c and Y w-ρ If the difference between the calculated results of Y and Y is greater than the set threshold (for example, 0.5%), resampling is performed. If the difference between the two calculated results is too large, it is determined whether an instrument failure has occurred. If Y w-c and Y w-ρ If the difference between the calculated results of is less than or equal to the set threshold, the average value of the two is taken as the final moisture content calculation result, as shown in formula (3):

[0063]

[0064] Among them, Y w Indicates moisture content, percentage; C o Indicates the ground reading (calibrated value) of the water holdup meter when the oil content is 100%, in Hz; C w When the water content is 100%, the ground reading of the water holdup meter (calibrated value) is in Hz; C m Indicates the water holdup meter reading under downhole pressure and temperature conditions, in Hz; ρ m Indicates the actual measured density value of the densitometer, ρ o Indicates the density of oil under downhole pressure and temperature conditions, ρ w Indicates the density of water under downhole pressure and temperature conditions.

[0065] Through the above calculation method, errors can be avoided as much as possible and the accuracy of the moisture content calculation results can be improved.

[0066] The real-time monitoring downhole high-pressure physical property sampling system and method provided by the present invention can control sampling in real time and improve efficiency. Conventional clock-controlled sampling construction technology, due to the uncontrollable operation time (complex situations encountered during the operation, which delayed the time, such as equipment failure or the instrument entering the well encountering obstacles), in order to avoid obtaining unqualified samples when the instrument has not reached the predetermined depth or the flow pressure has not yet stabilized, the clock preset time is usually increased. The present invention can control sampling on the ground when the sampling conditions are met, to avoid the downhole samples obtained being unqualified due to high water content or non-single phase of oil and gas, thereby improving the sampling success rate.

[0067] The downhole high-pressure physical property sampling system for real-time monitoring provided by the present invention adopts the WSCbus bus, and can adjust the instrument type according to the operation requirements to reduce the cost.

[0068] ① When the downhole is composed of oil and water phases, select the temperature / pressure + water holdup instrument (the instrument string combination is: high-pressure physical property sampler, sampling control short section, water holdup meter, temperature and pressure gauge and transmission control short section).

[0069] ② When the downhole is composed of three phases of oil, gas and water, choose to lower a full set of instruments (high-pressure physical property sampler, sampling control short section, density meter, water holdup meter, temperature and pressure gauge and transmission control short section).

[0070] The present invention provides a real-time monitoring downhole high-pressure physical property sampling system. The sampler has a unique address ID and can obtain multiple downhole formation fluid samples at one time according to the on-site conditions. The trigger mechanism can also be selectively controlled individually, so that downhole formation fluid samples can be taken individually or in batches at different times.

[0071] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A downhole high-pressure physical property sampling method for real-time monitoring, characterized in that: The downhole high-pressure physical property sampling system used for real-time monitoring includes: Downhole sampling device, which includes a high-pressure physical property sampler, a sampling control nipple, a density meter, a water holdup meter, a thermometer and a pressure gauge; a transmission nipple electrically connected to the downhole sampling device and used to collect data collected by the density meter, water holdup meter, thermometer and pressure gauge; a surface data processing and control system electrically connected to the transmission sub, receiving data transmitted by the transmission sub, and determining whether sampling conditions are met based on downhole pressure, temperature, water holdup, and density; and issuing a sampling command if the sampling conditions are met; The transmission short section receives the sampling command and transmits the sampling command to the sampling control short section, and the sampling control short section triggers the high-pressure physical property sampler; The downhole high-pressure physical property sampling method for real-time monitoring includes: Collect density, water holdup, temperature and pressure of downhole fluid; Determining whether the pressure of the downhole fluid is stable and higher than the bubble point pressure; Calculating the water content of the downhole fluid and determining whether the water content of the downhole fluid meets the sampling requirements; If the pressure of the downhole fluid is stable and higher than the bubble point pressure, and the water content of the downhole fluid meets the sampling requirements, controlling the high-pressure physical property sampler to start sampling; The water content of the downhole fluid is calculated by the following formula: Among them, Y w Indicates moisture content, percentage; Y w-c Indicates the moisture content value obtained by water holdup, Y w-ρ Indicates the moisture content value obtained from density; C o Indicates the ground reading of the water holdup meter when the fluid oil content is 100%; C w Indicates the ground reading of the water holdup meter when the fluid water content is 100%; C m Indicates the water holdup meter reading under downhole pressure and temperature conditions; ρ m Indicates the actual measured density value of the densitometer, ρ o Indicates the density of oil under downhole pressure and temperature conditions, ρ w Indicates the density of water under downhole pressure and temperature conditions.

2. The downhole high-pressure physical property sampling method for real-time monitoring according to claim 1, characterized in that: The ground data processing and control system includes a moisture content calculation module and a real-time imaging module; The water content calculation module calculates the water content of the downhole fluid in real time; and the real-time imaging module generates a water content curve graph according to the water content of the downhole fluid.

3. The downhole high-pressure physical property sampling method for real-time monitoring according to claim 2 is characterized in that: The transmission sub collects data collected by the density meter, water holdup meter, thermometer and pressure gauge through the Tbus.

4. The downhole high-pressure physical property sampling method for real-time monitoring according to claim 2 or 3, characterized in that: The transmission sub transmits data to the ground data processing and control system via the WSCbus.

5. The downhole high-pressure physical property sampling method for real-time monitoring according to claim 4, characterized in that: When the downhole fluid pressure satisfies: P wf >P b +1.0, and the pressure variation of three adjacent sampling points does not exceed 0.05%, then the downhole fluid pressure is judged to be stable and higher than the bubble point pressure; Among them, P wf Indicates the pressure of downhole fluid, P b Indicates the bubble point pressure in MPa.

6. The downhole high-pressure physical property sampling method for real-time monitoring according to claim 5, characterized in that: The time interval between adjacent sampling points is set to 15 minutes.

7. The downhole high-pressure physical property sampling method for real-time monitoring according to claim 6, characterized in that: If the water content of the downhole fluid is less than 5%, it is determined that the water content of the downhole fluid meets the sampling requirements.

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