Leaking stoppage simulation physical model evaluation method
By performing three-way stress loading and fracturing of the core in a true three-axis physical simulation experimental device, combined with the leakage plugging slurry of the leakage plugging formula to be tested, the leakage plugging simulation model evaluation was carried out, and the formation crack leakage plugging in the existing technology was solved. The problem of the gap between the model and the real strata has been evaluated, and more accurate evaluation of leakage plugging effect and effective leakage plugging of strata cracks have been achieved.
Patent Information
- Application Number
- CN202311029386.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-15
- Publication Date
- 2025-02-21
AI Technical Summary
There is a big gap between the crack model used for stratigraphic crack plugging evaluation in the prior art and the real stratigraphic cracks, resulting in a big gap between indoor experimental results and on-site application, and the selected leak plugging materials have poor on-site application effect.
A leak-blocking simulation model evaluation method is adopted. By obtaining the core and loading three-way stress in the true three-axis physical simulation experimental device, fracturing fluid is injected into the required cracks, and the leak-blocking method is used to measure the leak-blocking formula. The leak plugging experiment was conducted for the slurry to obtain the pressure curve and leakage loss, and then the leak plugging effect of the leak plugging formula was evaluated.
This method can truly restore stratigraphic cracks, accurately evaluate the performance of leak plugging formula, and effectively improve the leak plugging effect of stratigraphic cracks.
Smart Images
Figure CN119492487A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of formation fractures and relates to a plugging simulation model evaluation method. Background Art
[0002] Well leakage is the phenomenon that a large amount of drilling fluid flows into the formation during the drilling process. Well leakage not only consumes a large amount of drilling fluid and prolongs the drilling cycle, but improper handling may also lead to complex situations such as well collapse, blowout, and drill sticking, and even cause the wellbore to be scrapped, which will cause serious economic losses. As oil and gas exploration and development expands to deep, ultra-deep, deep ocean and other fields, the geological conditions are more stringent and the problem of well leakage is more prominent. Therefore, it is necessary to select appropriate plugging materials and plugging processes through plugging experiment evaluation to achieve the purpose of plugging the formation and drilling safely.
[0003] However, the fracture models used in the existing methods for evaluating the plugging of formation fractures are mostly made of steel plates, which are quite different from the actual fracture leakage channels. A few methods that use cores to simulate fractures have the problem that the simulated fracture size is small and the fracture width cannot be controlled to a fixed value. Traditional fracture plugging simulation technology methods are difficult to truly simulate the downhole fracture conditions, resulting in a large gap between the indoor experimental results and the field application, resulting in poor field application effects of the selected plugging materials, and failure to effectively plug the formation fractures. Summary of the invention
[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a plugging simulation model evaluation method that can truly restore formation fractures, more accurately evaluate the performance of plugging formulas, and effectively improve the plugging effect of formation fractures.
[0005] In order to achieve the above object, the present invention adopts the following technical solutions:
[0006] A plugging simulation physical model evaluation method includes the following steps:
[0007] S1, obtain core;
[0008] S2, applying triaxial stress to the core through a true triaxial physical simulation experimental device, injecting fracturing fluid to fracture the core to obtain the required fractures;
[0009] S3, making a pad according to the crack model and placing the pad into the crack;
[0010] S4, injecting the plugging slurry made with the plugging formula to be tested into the crack where the pad is placed;
[0011] S5, placing the core injected with the plugging slurry into a true triaxial physical simulation experimental device, using the true triaxial physical simulation experimental device to load triaxial stress on the core, obtaining the plugging pressure curve and the leakage amount, and then evaluating the plugging effect of the plugging formula.
[0012] Preferably, the core is an outcrop core or an artificial core.
[0013] Furthermore, the production process of artificial core is as follows: cement, quartz sand, silica fume, mineral powder and additives are mixed and stirred in proportion, poured into a mold after sufficient stirring, and shaken and smoothed. After solidifying in the mold for one day, the cement core is taken out and placed in a water pool for curing for more than one week to obtain an artificial core.
[0014] Preferably, before S2, the core is processed and cut into the required size, a surface is selected for drilling, the diameter of the drill hole is slightly larger than the designed simulated wellbore, the drilling depth is greater than the length of the simulated wellbore entering the core, the upper part of the simulated wellbore is connected to the injection pipeline through a thread, a raw tape is wrapped around the lower end of the simulated wellbore, the diameter of the lower end of the simulated wellbore is expanded, and the lower end of the simulated wellbore is placed in the drill hole.
[0015] Preferably, the core size is 25cm×25cm×25cm-30cm×30cm×30cm.
[0016] Preferably, the pressure range of the triaxial stress is 0-30 MPa.
[0017] Preferably, the process of making the pad is: using a three-dimensional scanning device to collect point cloud data of the crack surface and establish a three-dimensional model of the crack surface; using three-dimensional data processing software to process the point cloud data of the crack surface, and importing the processed data into the three-dimensional model of the crack surface to obtain a digital model of the pad, the upper part of the digital model of the pad is cut from the upper crack surface, and the lower part of the pad model is cut from the lower crack surface, and the digital model of the pad is printed with a 3D printer to obtain the pad.
[0018] Preferably, the thickness of the backing plate is 3mm-5mm.
[0019] Preferably, the backing plate is made of resin.
[0020] Preferably, the crack is a horizontal crack, dividing the entire core into two, and there are two pads, which are respectively located on both sides of the crack, to support the crack between the two pads to a set height.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] The core of the present invention is placed in a true triaxial physical model plugging experimental device to load triaxial stress, and a plugging slurry is configured to carry out a plugging experiment to obtain the plugging bearing pressure and leakage amount of the plugging body, and the plugging effect of the plugging slurry is evaluated according to the plugging bearing pressure and leakage amount. The evaluation result is accurate, and the crack width is effectively controlled by using a gasket to support the crack. The operation is simple, and the true triaxial physical model plugging experimental device can truly restore the formation cracks, and finally effectively improve the plugging effect of the formation cracks. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a flow chart of the leak plugging simulation model evaluation method of the present invention;
[0024] Figure 2 It is a comparison chart of the pressure curves of Formula 1 and Formula 2 of the present invention. DETAILED DESCRIPTION
[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0026] It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to directions in the drawings, and the words "inside" and "outside" refer to directions toward or away from the geometric center of a specific component, respectively.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0028] like Figure 1 As shown in FIG. 1 , the plugging simulation physical model evaluation method of the present invention includes the following steps:
[0029] 1. Collect outcrop cores from the same stratum as the core fractures to be simulated or make artificial cement cores based on the outcrop cores.
[0030] 2. Process the core into the style required for the experiment.
[0031] 3. Use the true triaxial physical simulation experimental device to load triaxial stress, connect pipelines, and inject fracturing fluid to fracture the core to obtain the required cracks. By controlling the triaxial stress to control the angle between the crack and the wellbore, the desired fracture inclination angle can be obtained.
[0032] 4. Perform a three-dimensional scan of the crack surface and establish a crack model. Make a 3D printed pad based on the crack model. During the experiment, place the 3D printed pad into the crack to support the crack and control the crack width.
[0033] 5. Place the core equipped with the 3D printed pad into a true triaxial physical simulation experimental device, use the true triaxial physical simulation experimental device to load triaxial stress on the core equipped with the 3D printed pad, obtain the plugging pressure curve and leakage amount, and evaluate the plugging formula based on these data, repeat the above steps, and select the best plugging formula from multiple plugging formulas.
[0034] Artificial core production method:
[0035] Prepare cement, quartz sand, silica fume, mineral powder and other additives in advance.
[0036] Add the materials into the mixer truck and mix according to the formula ratio.
[0037] After stirring thoroughly, pour into the mold, shake and smooth it.
[0038] After solidifying in the mold for one day, the cement core is taken out and placed in a water pool for curing for more than one week to obtain an artificial core.
[0039] The core processing process is:
[0040] The outcrop or artificial core is cut into standard size rock samples (25cm×25cm×25cm-30cm×30cm×30cm).
[0041] Drilling: Select a surface for drilling, and the diameter of the drill hole is slightly larger than the designed simulated wellbore. The drilling depth should be greater than the length of the simulated wellbore entering the core. After the simulated wellbore is "cemented", an open hole section can be formed.
[0042] Make a simulated wellbore: The upper part of the simulated wellbore is connected to the injection pipeline through threads, and the lower part enters the core borehole. The step design can increase the outer area of the simulated wellbore, with more contact surfaces and tighter bonding during "cementing".
[0043] Cementing: Wrap the raw tape around the lower end of the simulated wellbore to expand the diameter of the lower end of the simulated wellbore, and then insert it into the borehole to tighten the simulated wellbore and the core.
[0044] True triaxial physical simulation experimental device:
[0045] The true triaxial physical simulation experimental device mainly consists of five parts: true triaxial stress loading chamber, confining pressure loading system, ISCO injection pump, data acquisition system, and drilling fluid storage tank (intermediate container).
[0046] The true triaxial stress loading chamber is a device for applying triaxial stress. The core is loaded into the platform device, the iron plate and the jack are assembled, the bolts are tightened, and the jack is pressurized by the confining pressure loading system. The pressure of the three jacks is controlled by the controller. The purpose of applying triaxial stress is achieved.
[0047] The confining pressure loading system is composed of an oil pump, a pressure gauge, a controller, a jack, etc. It can provide three-dimensional stress and control its size.
[0048] ISCO injection pumps can provide drilling fluid injection pressures up to 50MPa, and can perform double pump alternating injections uninterruptedly.
[0049] The drilling fluid storage tank (intermediate container) can store 4L of drilling fluid on the upper part of the plunger. The lower part of the plunger is connected to the ISCO injection pump, which injects water and pressurizes the lower part of the plunger, transferring the pressure to the drilling fluid so that it enters the core.
[0050] When the core is in the true triaxial physical simulation experimental device for the first time, there is no crack in the core at this time. It is necessary to hold pressure in the core pipeline to press the core into two halves to create cracks. Use fracturing fluid. The process is that the plunger pump injects water into the middle container, which is the liquid storage tank. The fracturing fluid on the top of the liquid storage tank flows out of the container, and the fracturing fluid flows out of the container into the pipeline, and then into the core from the pipeline. There is a pipe mouth made above the core, and it enters the core from here. It is continuously injected and held pressure in the wellbore until the core is fractured and cracks are formed.
[0051] When the core is in the true triaxial physical simulation experiment device for the second time, the plunger pump injects water into the middle container, which is the liquid storage tank. The drilling fluid on the top of the liquid storage tank exits the container, enters the pipeline, and enters the core from the pipeline. There is a simulated wellbore made above the core. The core enters from here and enters the crack in the middle of the crack and spreads to the surroundings. Some plugging materials are retained in the crack to form a plug. Continue to inject water, and the water top drilling fluid continues to enter the crack. The drilling fluid tops the plugging material in the crack to form a plugging body, and the pressure gradually increases.
[0052] The data acquisition system consists of a pressure sensor and pressure recording software on a computer, which can record pressure data once a second.
[0053] The main technical parameters of the device are as follows:
[0054] Three-way confining pressure: 0-30MPa.
[0055] ISCO injection pump injection pressure: 0-50MPa.
[0056] Physical model core size: 25cm×25cm×25cm-30cm×30cm×30cm.
[0057] Working temperature: 0-150℃.
[0058] Drilling fluid volume: 4L.
[0059] How to make a 3D printed pad:
[0060] Use 3D scanning equipment to collect point cloud data of the crack surface and establish a 3D model of the crack surface.
[0061] Delineate the area of pad support on the crack face.
[0062] The point cloud data of the crack surface is processed using three-dimensional data processing software, and the processed point cloud data is imported into the above-mentioned three-dimensional model of the crack surface to obtain a digital model of the pad. The upper part of the digital model of the pad is cut from the upper crack surface, and the lower part of the digital model of the pad is cut from the lower crack surface. The thickness is set to 3mm-5mm.
[0063] The digital model of the pad is printed using a resin 3D printer to obtain the pad.
[0064] In the present application, the crack is a horizontal crack, dividing the entire core into two. There are two pads, which are located on both sides of the crack to support the crack. The drill hole is located between the two pads, and the two pads support the crack to a certain height.
[0065] The cracks produced by the present invention are naturally generated by fracturing, and the degree of simulation of the crack surface is higher. It can be used not only for artificial cores but also for outcrop cores. Since the width of underground cracks is different during leakage, a method for controlling the crack width is required. The crack width can be controlled by supporting the crack width with a 3D printed pad to simulate cracks of different widths. The method provided by the present invention can control the crack direction by controlling the magnitude of the three-dimensional stress during fracturing, and obtain cracks of different inclination angles.
[0066] The core structure is designed according to the actual situation of the downhole fractures, which can simulate the fracture leakage around the well wall. The core is taken from the leakage layer and has the same roughness as the real fracture, which makes this plugging simulation model evaluation method have a strong similarity with the real fracture.
[0067] By controlling the triaxial stress, the crack direction is controlled, cracks with different inclination angles are created, and the application effect of the plugging formula at different inclination angles is evaluated.
[0068] The pads were made by three-dimensional scanning and 3D printing technology and placed in the cracks during the experiment, which can achieve the purpose of controlling the crack width and solve the problem of crack width control in the field of true triaxial physical model plugging. This method can evaluate the plugging effect under different crack widths.
[0069] According to the above method, two groups of plugging formulas were evaluated, and the plugging formulas are shown in Table 1:
[0070] Table 1 Recipe
[0071]
[0072] The experimental results are as follows Figure 2As shown in the figure, according to the pressure curve, it can be seen that formula 2 is very easy to break after pressurization, indicating that the plugging formed is not tight enough. The curve of formula 1 has fewer waves, indicating that there are fewer ruptures during the pressurization process. Therefore, formula 1 is preferred among the two formulas.
[0073] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.
[0074] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the foregoing claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.
Claims
1. A plugging simulation physical model evaluation method, characterized in that: The process includes: S1, obtain core; S2, applying triaxial stress to the core through a true triaxial physical simulation experimental device, injecting fracturing fluid to fracture the core to obtain the required fractures; S3, making a pad according to the crack model and placing the pad into the crack; S4, injecting the plugging slurry made with the plugging formula to be tested into the crack where the pad is placed; S5, placing the core injected with the plugging slurry into a true triaxial physical simulation experimental device, using the true triaxial physical simulation experimental device to load triaxial stress on the core, obtaining the plugging pressure curve and the leakage amount, and then evaluating the plugging effect of the plugging formula.
2. The plugging simulation physical model evaluation method according to claim 1, characterized in that: The cores are outcrop cores or artificial cores.
3. The leak plugging simulation physical model evaluation method according to claim 2, characterized in that: The production process of artificial core is as follows: mix cement, quartz sand, silica fume, mineral powder and additives in proportion, pour them into the mold after sufficient stirring, shake and smooth them, solidify in the mold for one day, take out the cement core, place it in a pool for curing for more than one week, and obtain the artificial core.
4. The plugging simulation physical model evaluation method according to claim 1, characterized in that: Before S2, the core is processed and cut into the required size. A surface is selected for drilling. The diameter of the hole is slightly larger than the designed simulated wellbore. The drilling depth is greater than the length of the simulated wellbore entering the core. The upper part of the simulated wellbore is connected to the injection pipeline through a thread. The raw tape is wrapped around the lower end of the simulated wellbore to expand the diameter of the lower end of the simulated wellbore, and the lower end of the simulated wellbore is placed in the borehole.
5. The plugging simulation physical model evaluation method according to claim 1, characterized in that: The core size is 25cm×25cm×25cm-30cm×30cm×30cm.
6. The plugging simulation physical model evaluation method according to claim 1, characterized in that: The pressure range of triaxial stress is 0-30MPa.
7. The plugging simulation physical model evaluation method according to claim 1, characterized in that: The process of making the pad is: use a three-dimensional scanning device to collect point cloud data of the crack surface and establish a three-dimensional model of the crack surface; use three-dimensional data processing software to process the point cloud data of the crack surface, and import the processed data into the three-dimensional model of the crack surface to obtain a digital model of the pad. The upper part of the digital model of the pad is cut from the upper crack surface, and the lower part of the pad model is cut from the lower crack surface. The digital model of the pad is printed with a 3D printer to obtain the pad.
8. The leak plugging simulation physical model evaluation method according to claim 1, characterized in that: The thickness of the pad is 3mm-5mm.
9. The plugging simulation physical model evaluation method according to claim 1, characterized in that: The backing plate is made of resin.
10. The leak plugging simulation physical model evaluation method according to claim 1, characterized in that: The crack is a horizontal crack, dividing the entire core into two. There are two pads, which are located on both sides of the crack, supporting the crack between the two pads to a set height.