CN115370341B - Microcosmic visual rock plate hydraulic fracturing indoor simulation method and device - Google Patents
Microcosmic visual rock plate hydraulic fracturing indoor simulation method and device Download PDFInfo
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- 238000004088 simulation Methods 0.000 title claims abstract description 52
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- 239000003795 chemical substances by application Substances 0.000 claims abstract description 35
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- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 239000011521 glass Substances 0.000 claims description 47
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- 239000012530 fluid Substances 0.000 claims description 24
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
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Abstract
The invention provides a microscopic visual rock plate hydraulic fracturing indoor simulation method and device, wherein the method comprises the steps of manufacturing an experimental sample provided with a liquid injection hole and a preset crack; parameters of a liquid injection hole and a preset crack are obtained, and a complex working condition of hydraulic crack expansion is simulated; presetting a plurality of natural cracks with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic cracks in a crack body; presetting a plurality of natural fracture holes with different forms on an experimental sample, and simulating the initiation and expansion of hydraulic cracks in a fracture hole body; filling temporary plugging agent at the tip of the preset crack, and simulating temporary plugging steering fracturing working condition. The microscopic visual rock plate hydraulic fracturing indoor simulation method can intuitively monitor the dynamic expansion rule of the hydraulic fracture under the ground stress condition of a real reservoir, record the dynamic expansion process of the fracture in real time, provide a new method for the experimental study in the hydraulic fracturing indoor, and practically promote the progress of the hydraulic fracturing experiment to the refinement and quantification directions.
Description
Technical Field
The invention belongs to the technical field of hydraulic fracturing development of oil and gas reservoirs, and particularly relates to an indoor simulation method and device for hydraulic fracturing of a microcosmic visual rock plate.
Background
The reserve of unconventional oil and gas resources in China is huge, and hydraulic fracturing is the most commonly used reservoir reconstruction process for efficiently developing unconventional oil and gas resources at present. Large-scale volume fracturing is carried out through a horizontal well and multistage fracturing, so that a large number of hydraulic cracks can be formed in an unconventional reservoir, the drainage area of the reservoir is greatly increased, and a large number of oil gas migration channels with high diversion capacity are formed, thereby greatly improving unconventional oil gas exploitation conditions and improving recovery ratio.
With the successful application of hydraulic fracturing in the unconventional oil and gas field and the year-by-year increase of unconventional oil and gas exploitation difficulty, higher requirements are put on a research method of a hydraulic fracturing crack extension mechanism. In order to provide powerful and reliable technical support for the on-site fracturing design and construction scheme through experimental study, more visual, quantitative and diversified experimental methods are needed to be provided for the hydraulic fracturing indoor experiment on the basis of simulating the ground stress state of a real stratum, the traditional hydraulic fracturing experiment is difficult to accurately monitor the dynamic expansion path of a hydraulic fracture, the interaction with a natural fracture or a natural fracture hole and the dynamic expansion path of the fracture after a temporary plugging process, quantitative analysis is difficult to be carried out on the form of the hydraulic fracture after the experiment is finished, and the hydraulic fracture initiation and expansion process is difficult to accurately trace through experimental results.
Disclosure of Invention
The invention mainly aims to provide an indoor simulation method and an indoor simulation device for micro-visual rock plate hydraulic fracturing, and aims to solve the technical problem that the indoor simulation method for micro-visual rock plate hydraulic fracturing in the prior art cannot intuitively reflect quantitative dynamic change parameters of hydraulic fractures.
In order to achieve the above object, the present invention provides a microscopic visual rock plate hydraulic fracturing indoor simulation method, comprising:
manufacturing an experimental sample provided with a liquid injection hole and a preset crack;
designing parameters of the liquid injection hole and the preset crack, and simulating a complex working condition of hydraulic crack expansion;
presetting a plurality of natural cracks with different forms on the experimental sample, and simulating the initiation and the expansion of hydraulic cracks in a crack body;
presetting a plurality of natural fracture holes with different forms on the experimental sample, and simulating the initiation and expansion of hydraulic cracks in a fracture hole body;
filling temporary plugging agent at the tip of the preset crack, and simulating the working condition of temporary plugging steering fracturing.
In an embodiment of the present invention, the step of designing parameters of the injection hole and the preset fracture and simulating a complex working condition of hydraulic fracture expansion includes:
when the number of the preset cracks is one, acquiring morphological parameters of the hydraulic cracks;
Comparing crack initiation and expansion images of the hydraulic cracks under different preset crack forms in a plurality of experimental samples;
and evaluating the influence of the morphological parameters, the three-dimensional stress relation and the injection flow of the preset crack on the crack initiation and expansion according to the comparison result.
In an embodiment of the present invention, the step of designing parameters of the injection hole and the preset fracture and simulating a complex working condition of hydraulic fracture expansion includes:
when the number of the preset cracks is multiple, controlling the liquid injection sequence of the liquid injection holes in the experimental sample so as to simulate the complex working conditions of cracking and expanding of the closely-cut fracturing crack group;
and (3) designing morphological parameters of a plurality of preset cracks in the experimental sample, and obtaining the expansion form of a crack group and the mutual interference rule among a plurality of hydraulic cracks under the closely-cut fracturing working condition.
In an embodiment of the present invention, the steps of presetting a plurality of natural cracks with different forms on the experimental sample and simulating the initiation and the extension of the hydraulic cracks in the crack body include:
designing an interaction relation between a preset crack and a natural crack according to the actual working condition in the reservoir;
when the natural fracture is not intersected with the predicted expansion path of the hydraulic fracture, acquiring an influence rule of a stress field under the influence of the natural fracture on the expansion of the hydraulic fracture;
And when the natural fracture intersects with the expected expansion path of the hydraulic fracture, acquiring an interaction influence rule between the natural fracture and the hydraulic fracture.
In an embodiment of the present invention, the steps of presetting a plurality of natural fracture holes with different shapes on the experimental sample and simulating the initiation and the extension of the hydraulic fracture in the fracture hole body include:
designing an interaction relation between a preset fracture and a natural fracture hole according to the actual working condition in the reservoir;
when the natural fracture hole is not intersected with the predicted expansion path of the hydraulic fracture, acquiring an influence rule of a stress field under the influence of the natural fracture hole on the expansion of the hydraulic fracture;
and when the natural fracture hole is intersected with the expected expansion path of the hydraulic fracture, acquiring an interaction rule between the natural fracture hole and the hydraulic fracture.
In the embodiment of the invention, the step of filling temporary plugging agent at the tip of the preset crack and simulating temporary plugging steering fracturing working condition comprises the following steps:
the method comprises the steps of designing morphological parameters of temporary plugging agents in a joint according to actual working conditions and temporary plugging processes in a reservoir;
filling temporary plugging agents of corresponding types and forms at the tips of preset cracks according to the form parameters of the temporary plugging agents;
and obtaining a steering expansion rule of the hydraulic fracture under the corresponding temporary plugging process after the experiment.
In an embodiment of the present invention, a microscopic visual rock plate hydraulic fracturing indoor simulation apparatus is further provided, and the microscopic visual rock plate hydraulic fracturing indoor simulation method described above is performed by using the simulation apparatus, where the microscopic visual rock plate hydraulic fracturing indoor simulation apparatus includes:
the inner part of the outer kettle body is provided with a sealed cylindrical space, the top of the outer kettle body is arranged in a transparent manner, a sample seat for placing a sample is arranged in the cylindrical space, and a liquid injection hole is formed in the bottom of the sample seat;
the image acquisition assembly is axially arranged above the outer kettle body and is used for acquiring dynamic images of the sample in the outer kettle body in the fracturing process;
the lateral confining pressure hydraulic cylinder and the vertical confining pressure hydraulic cylinder apply loads to the sample along the X direction, the Y direction and the Z direction respectively in the same plane;
and the fluid injection pump is connected with the liquid injection hole through a pipeline and is used for injecting liquid to the sample from the bottom.
In the embodiment of the invention, the outer kettle body comprises an outer barrel, an upper top cover, a base plate and a glass pressing plate, wherein the upper top cover and the base plate are arranged at the top end and the bottom end of the outer barrel, the glass pressing plate is arranged on the upper top cover, a window opening which is convenient for observing the inside of the outer kettle body is formed in the center of the upper top cover, the glass pressing plate is of an annular plate-shaped structure, an installation groove for embedding window glass is formed in the inner side wall of the glass pressing plate along the circumferential direction, and the window glass coaxially covers the window opening.
In the embodiment of the invention, the sample holder comprises a circular chassis and a sample table arranged at the center of the circular chassis, a guide hole is formed in the circular chassis, the circular chassis and the base plate are coaxially arranged and are connected in a guide way through a guide shaft, the bottom end of the guide shaft is arranged on the base plate, and the top end of the guide shaft penetrates through and is locked in the guide hole.
In the embodiment of the invention, the indoor simulation device for hydraulic fracturing of the microscopic visual rock plate further comprises a glass plug, two ends of which are respectively abutted against the window glass and the sample, and a dislocation loading plate group arranged on the sample seat, wherein the glass plug, the sample and the sample table jointly form a rectangular cylinder, a sealing rubber sleeve is sleeved on the outer side wall of the sample, the dislocation loading plate group is of a rectangular frame structure formed by clamping and enclosing four dislocation loading plates, and the inner side of the dislocation loading plate group is tightly and tightly adhered to the outer side wall of the sealing rubber sleeve.
Through the technical scheme, the microscopic visual rock plate hydraulic fracturing indoor simulation method provided by the embodiment of the invention has the following beneficial effects:
In the simulation process, firstly, an experimental sample provided with a liquid injection hole and a preset crack is manufactured; parameters of a liquid injection hole and a preset crack are obtained, and a complex working condition of hydraulic crack expansion is simulated; presetting a plurality of natural cracks with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic cracks in a crack body; presetting a plurality of natural fracture holes with different forms on an experimental sample, and simulating the initiation and expansion of hydraulic cracks in a fracture hole body; filling temporary plugging agent at the tip of a preset crack, and simulating temporary plugging steering fracturing working conditions; the method can realize the visual monitoring of the dynamic expansion of the hydraulic fracture of the experimental sample under the ground stress condition of the real reservoir, truly record the dynamic expansion process of the fracture, provide a new method for the experimental study in the hydraulic fracturing room, practically promote the progress of the hydraulic fracturing experiment to the refinement and quantification directions and greatly expand the research method of the hydraulic fracturing experiment.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide an understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:
FIG. 1 is a schematic flow chart of a method for simulating a hydraulic fracturing chamber of a microscopic visual rock plate according to an embodiment of the invention;
FIG. 2 is a schematic diagram of an assembly structure of a simulation device in a micro-visual rock plate hydraulic fracturing chamber according to an embodiment of the invention;
FIG. 3 is a schematic view of a part of a simulation device in a micro-visual rock plate hydraulic fracturing chamber according to an embodiment of the invention;
FIG. 4 is a schematic view, partially in section, of a simulation apparatus in a micro-visualization rock panel hydraulic fracturing chamber in accordance with an embodiment of the invention;
FIG. 5 is a schematic view of a structure of a staggered loading plate set in a micro-visual rock plate hydraulic fracturing indoor simulation apparatus according to an embodiment of the present invention;
FIG. 6 is a schematic view of the structure of a sample holder in a simulation apparatus in a micro-visual rock hydraulic fracturing chamber according to an embodiment of the present invention;
FIG. 7 is a schematic view of the structure of a base plate of a micro-visual rock plate hydraulic fracturing indoor simulation apparatus according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of the structure of an experimental sample in a simulation device in a micro-visual rock hydraulic fracturing chamber according to an embodiment of the invention;
FIG. 9 is a schematic diagram of preset fracture morphology parameters of an experimental sample in a microscopic visual rock hydraulic fracturing indoor simulation method according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of stress loading of an experimental sample in a simulation method in a hydraulic fracturing chamber of a microscopic visual rock plate in accordance with an embodiment of the present invention;
FIG. 11 is a schematic illustration of the location and morphology of natural fractures of an experimental sample in a microscopic hydraulic fracturing room simulation method of a rock board in accordance with an embodiment of the present invention;
FIG. 12 is a schematic view of the location and morphology of a natural fracture hole of an experimental sample in a microscopic hydraulic fracturing indoor simulation method of a rock plate according to an embodiment of the present invention;
FIG. 13 is a scanning electron microscope image of the interaction of a hydraulic fracture and a natural fracture hole in a real rock plate;
FIG. 14 is a schematic illustration of the temporary plugging agent fill location and fill morphology in an experimental sample according to an embodiment of the invention;
FIG. 15 is a scanning electron microscope image of an experimental sample after being filled with temporary plugging agent according to an embodiment of the present invention;
fig. 16 is a schematic diagram showing the form of mutual interference of a plurality of hydraulic cracks in a microscopic visual rock plate hydraulic fracturing room simulation method according to an embodiment of the present invention.
Description of the reference numerals
Detailed Description
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration and explanation only and are not intended to limit the present invention.
The following describes a microscopic visualized rock plate hydraulic fracturing indoor simulation method according to the invention with reference to the accompanying drawings.
As shown in fig. 1, in an embodiment of the present invention, there is provided a microscopic visual rock plate hydraulic fracturing indoor simulation method, including:
step S10: manufacturing an experimental sample provided with a liquid injection hole and a preset crack;
step S20: designing parameters of a liquid injection hole and a preset crack, and simulating a complex working condition of hydraulic crack expansion;
step S30: presetting a plurality of natural cracks with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic cracks in a crack body;
step S40: presetting a plurality of natural fracture holes with different forms on an experimental sample, and simulating the initiation and expansion of hydraulic cracks in a fracture hole body;
step S50: filling temporary plugging agent at the tip of the preset crack, and simulating temporary plugging steering fracturing working condition.
It should be noted that the original existing crack in the sample before the experiment is called a preset crack, and the purpose is to guide the cracking position and direction of the crack propped by the water pressure in the experiment process. The fracture propped open by the water pressure after the experiment is called a hydraulic fracture. The two cracks are distinguished, and can be respectively a preset crack and a hydraulic crack.
The method comprises the steps of designing the injection displacement range to be 0-20 mL/min, wherein the size of an experimental sample in a microscopic visual rock plate hydraulic fracturing indoor simulation experiment is smaller; the confining pressure loading range is 0-20 MPa; the ground stress state and the fracturing construction parameters of most of unconventional reservoirs in China can be simulated according to the similarity theory. Specifically, the experimental sample is rectangular lamellar, the side length of the sample is between 50mm and 70mm, the thickness of the sample is between 3mm and 20mm, and the sample can be prepared by cutting a downhole rock core, an outcrop rock sample, an artificial rock sample and other materials, so long as the size meets the requirements.
The invention can realize the visual monitoring of the dynamic expansion of the hydraulic fracture of the experimental sample under the ground stress condition of the real reservoir, truly records the dynamic expansion process of the fracture, and can acquire more visual, quantitative and dynamic parameters related to the hydraulic fracture based on the post-treatment of visual materials, comprising the following steps: 1) dynamic recording of crack propagation paths, 2) quantitative dynamic change recording of crack widths, 3) flow characteristics of fluid in the process of dynamic crack propagation, 4) interaction of particle mineral and lithology interfaces and natural cracks and hydraulic cracks, and 5) actual stress and deformation characteristics of crack tips.
The invention provides five forms of simulating hydraulic fracture under the ground stress condition of a real reservoir, which covers a conventional fracture expansion experiment, a hydraulic fracture and natural fracture interaction experiment, a hydraulic fracture and natural fracture hole interaction experiment, a hydraulic fracture expansion experiment after temporary plugging and a plurality of hydraulic fracture mutual interference experiments, provides a new method for experimental research in a hydraulic fracturing room, really promotes the progress of the hydraulic fracturing experiment to the refinement and quantification directions, and greatly expands the research method of the hydraulic fracturing experiment.
In an embodiment of the present invention, the steps of designing parameters of the injection hole and the preset fracture and simulating the complex working condition of hydraulic fracture expansion include:
when the number of the preset cracks is one, acquiring morphological parameters of the hydraulic cracks;
comparing crack initiation and expansion images of the hydraulic cracks under different preset crack forms in a plurality of experimental samples;
and evaluating the influence of the morphological parameters, the three-dimensional stress relation and the injection flow of the preset crack on the crack initiation and expansion according to the comparison result.
Further, in the step of the simulation method, the experimental sample preparation mainly considers 2 elements under the conditions of satisfying the above dimensions and materials: the position of a sample liquid injection hole and the preset crack form of the sample.
The liquid injection hole of the hydraulic fracture expansion experiment can be arranged in the middle or at the edge of the sample, as shown in two left-hand diagrams in fig. 9, and when the liquid injection hole is arranged in the middle, the expansion of the double-wing fracture can be simulated but the fracture expansion path is relatively short; the liquid injection hole is arranged at the edge and used for simulating the expansion of the single-wing slit, and the crack expansion path is relatively long, so that the hydraulic slit far-end morphology can be observed.
When a sample is processed, a preset crack or not can be selected, the preset crack can play a role in controlling the cracking position of the crack and guiding the cracking direction of the crack, the morphological parameters of the preset crack comprise a crack length L, a crack width w and a deflection angle theta, wherein the crack length L is generally controlled between 5mm and 20mm, the crack width w is generally controlled between 0.1mm and 3mm, and the deflection angle theta can be set between-90 and 90 degrees, and the rightmost diagram in fig. 9 is shown. Different seam lengths can be used for researching the influence of seam tip stress conditions on crack initiation and expansion under the same injection conditions; different slit widths can be used for researching the influence of slit tip shapes (curvatures) on crack initiation and propagation; different deflection angles can be used to study the effect of different initiation directions on crack initiation and propagation.
In an embodiment of the present invention, the steps of designing parameters of the injection hole and the preset fracture and simulating the complex working condition of hydraulic fracture expansion include:
When the number of the preset cracks is multiple, controlling the liquid injection sequence of the liquid injection holes in the experimental sample so as to simulate the complex working conditions of cracking and expanding of the closely-cut fracturing crack group;
and (3) designing morphological parameters of a plurality of preset cracks in the experimental sample, and obtaining the expansion form of a crack group and the mutual interference rule among a plurality of hydraulic cracks under the closely-cut fracturing working condition.
In petroleum engineering, closely cut fractures can be intuitively understood as the simultaneous or successive initiation and propagation of multiple fractures. The multiple cracks under the working condition of close cutting and fracturing are vividly called as a crack group.
The simulation experiment method of the step is mainly used for simulating the problem of inter-seam interference in the field fracturing process. In the field fracturing process, under different fracturing designs, the condition that a plurality of cracks are expanded simultaneously in a certain space range often occurs, under the condition, induced stress is generated between the cracks (namely, each crack can prop up the stratum, the prop-up force is reflected in deformation of stratum rock, namely, the induced stress) and the induced stress can enable the plurality of hydraulic cracks to be extruded mutually, so that the crack expansion path and direction are changed. In the experiment, the process is simplified, different working conditions are simulated by controlling the parameters of preset cracks and the liquid injection sequence of the liquid injection holes, and the construction parameters are optimized by simulating complex working conditions of multi-crack competition expansion, so that references are provided for on-site fracturing construction.
And (3) preparing an experimental sample: the experimental sample preparation needs to drill a plurality of liquid injection holes and preset cracks on the basis of meeting the sample preparation requirements of conventional crack extension experiments, and mainly considers 3 factors: the positions and the number of the liquid injection holes, presetting the form of the natural cracks, and simultaneously or sequentially injecting liquid into a plurality of liquid injection holes in the experimental process.
In order to fully observe the mutual interference process of a plurality of hydraulic cracks, a liquid injection hole is generally arranged at the edge of an experimental sample, so that each hydraulic crack has a sufficient expansion space; the number of liquid injection holes is generally 2 to 10, which is limited by the size of the experimental sample, and is shown in the left picture in fig. 16.
When the sample is processed, each liquid injection hole can be preset or not, the form parameters of the preset cracks comprise a crack length L, a crack width w and a deflection angle theta, the control range of the form parameters of the cracks is consistent with the sample preparation requirement of a conventional crack extension experiment, and the mutual interference phenomenon among hydraulic cracks under different working conditions can be studied by setting the form parameters of different cracks, so that a right picture shown in fig. 16 is obtained.
According to the design of the experimental scheme, the joint connection or the sealing operation of the plurality of liquid injection holes at the bottom of the sample seat can be realized, the liquid injection holes can be simultaneously or sequentially injected, and the indoor simulation experiment of the mutual interference of hydraulic cracks under the complex working condition is satisfied.
In the embodiment of the invention, the steps of presetting a plurality of natural cracks with different forms on an experimental sample and simulating the initiation and the extension of the hydraulic cracks in a crack body comprise the following steps:
designing an interaction relation between a preset crack and a natural crack according to the actual working condition in the reservoir;
when the natural fracture is not intersected with the predicted expansion path of the hydraulic fracture, acquiring the rule of influence of the stress field under the influence of the natural fracture on the expansion of the hydraulic fracture;
when the natural fracture intersects with the expected propagation path of the hydraulic fracture, an interaction influence rule between the natural fracture and the hydraulic fracture is obtained.
And (3) preparing an experimental sample: the experimental sample preparation mainly considers 2 elements on the basis of meeting the sample preparation requirements of conventional crack propagation experiments: the preset position of the natural fracture and the preset natural fracture morphology.
The natural cracks can be preset at any position in the experimental samples, a plurality of natural cracks with different positions and shapes can be preset in one experimental sample according to the needs, and the intersection angle alpha of the natural cracks and the hydraulic cracks can be set to be 0-90 degrees.
Natural cracks which are not intersected with the predicted expansion paths of the hydraulic cracks are preset in the sample, in the experimental process, after a preset load is loaded, the natural cracks can enable the sample to deform unevenly, and then an uneven stress field is formed, in the hydraulic crack expansion process, the expansion direction and the paths of the hydraulic cracks can be influenced by the uneven stress field, and the hydraulic crack expansion device can be used for researching the influence of the stress field under the influence of the natural cracks on the hydraulic crack expansion.
The natural fracture intersected with the expected expansion path of the hydraulic fracture is preset in the sample, 2 or more expansion paths are provided for the hydraulic fracture in the experimental process, and the hydraulic fracture can be expanded in different directions along with the change of the ground stress condition and the intersection angle alpha of the natural fracture and the hydraulic fracture. Can be used for researching the interaction between hydraulic fracture and natural fracture. By combining the two methods for presetting the natural cracks, the hydraulic crack expansion process in the complex crack body of the real stratum can be simulated. From the left in fig. 9The position where the natural fracture can be preset, the optional form of the preset natural fracture and the included angle of 30 degrees between the preset single natural fracture and the hydraulic fracture are displayed in sequence to the right. The stress loading of the experimental sample is shown in FIG. 10, wherein σ H Is the maximum horizontal principal stress, sigma h Is the minimum horizontal principal stress, sigma v Is the overburden stress. The experiment mainly researches influence sigma H Sum sigma h Impact on crack propagation direction and path. Sigma (sigma) H ≥σ h Theoretically the hydraulic fracture edge sigma H Direction expansion, so that the hydraulic fracture is generally perpendicular to σ h The preset natural fracture forms a certain included angle with the hydraulic fracture.
The experimental aim is to optimize the specific construction parameters of the crack bodies with different shapes by simulating the initiation and the expansion of the hydraulic cracks in the crack bodies, so as to provide references for the on-site fracturing construction.
The length of the preset natural crack is generally larger than 5mm, the longest does not penetrate through the experimental sample, the width of the natural crack is generally controlled between 0.1 and 3mm, and as shown in fig. 11, the shape of the natural crack can be linear, broken line, curve or other irregular shapes.
In the embodiment of the invention, the steps of presetting a plurality of natural fracture holes with different forms on an experimental sample and simulating the initiation and the extension of hydraulic fracture in a fracture hole body comprise the following steps:
designing an interaction relation between a preset fracture and a natural fracture hole according to the actual working condition in the reservoir;
when the natural fracture hole is not intersected with the predicted expansion path of the hydraulic fracture, acquiring the rule of influence of the stress field under the influence of the natural fracture hole on the expansion of the hydraulic fracture;
and when the natural fracture hole intersects with the expected expansion path of the hydraulic fracture, acquiring an interaction rule between the natural fracture hole and the hydraulic fracture.
And (3) preparing an experimental sample: the experimental sample preparation mainly considers 2 elements on the basis of meeting the sample preparation requirements of conventional crack propagation experiments: the preset position of the natural seam hole and the shape of the natural seam hole.
The natural seam holes can be preset at any position in the experimental samples, and a plurality of natural seam holes with different positions and shapes can be preset in one experimental sample according to the needs.
As shown in fig. 13, a natural fracture hole which is not intersected with the predicted expansion path of the hydraulic fracture is preset in the sample, in the experimental process, after a preset load is loaded, the natural fracture hole can enable the sample to deform unevenly, so that an uneven stress field is formed, in the hydraulic fracture expansion process, the expansion direction and the expansion path of the hydraulic fracture can be influenced by the uneven stress field, and the influence of the stress field under the influence of the natural fracture hole on the hydraulic fracture expansion can be studied.
The method comprises the steps that a natural fracture hole intersected with a hydraulic fracture predicted expansion path is preset in a sample, expansion is stopped temporarily after the hydraulic fracture meets a fracture hole body in the experimental process, the fracture hole body is filled with high-pressure fluid, the hydraulic fracture can be restarted and expanded from a weak point of the fracture hole body along with the rising of the pressure in the fracture hole body, and different paths can be selected for expansion along with the change of ground stress conditions and the fracture hole body shape. Can be used for researching the interaction between the hydraulic fracture and the natural fracture hole; by combining the two methods for presetting the natural cracks, the hydraulic crack expansion process in the complex fracture-cavity body of the real stratum can be simulated.
The left and middle panels of fig. 11 show the locations where the natural perforation may be preset, and the right-most panel of fig. 11 shows an alternative form of presetting the natural perforation.
The experimental aim is to optimize the specific construction parameters of the fracture-cavity bodies with different shapes by simulating the initiation and the expansion of the hydraulic fracture in the fracture-cavity body, and provide references for the on-site fracturing construction.
Presetting the length D of the long axis of the natural fracture hole 1 The natural fracture-cavity shape can be round, elliptic or other irregular shape, and is controlled between 0.5 mm and 20mm generally, without penetrating through experimental samples, and the right-hand graph of fig. 12 is seen.
In the embodiment of the invention, the step of filling temporary plugging agent at the tip of the preset crack and simulating temporary plugging steering fracturing working condition comprises the following steps:
the method comprises the steps of designing morphological parameters of temporary plugging agents in a joint according to actual working conditions and temporary plugging processes in a reservoir;
filling temporary plugging agents of corresponding types and forms at the tips of preset cracks according to the form parameters of the temporary plugging agents;
and obtaining a steering expansion rule of the hydraulic fracture under the corresponding temporary plugging process after the experiment.
In the hydraulic fracturing site construction process, the results of small crack spreading range and poor reservoir reconstruction effect caused by single crack form can exist. Therefore, in order to increase the complexity of the crack propagation path and increase the crack spreading range, temporary plugging agent is added after the crack propagates for a certain distance, so that the crack is difficult to continue to propagate along the original direction, but the crack is turned and propagated from the weak part of the existing crack surface. The experimental method is used for simulating the field construction scheme of the oil field and observing the expansion rule of the crack under different temporary plugging conditions. The experimental aim is to optimize the pumping parameters, the type of temporary plugging agent and the filling quantity of temporary plugging agent by simulating the temporary plugging steering fracturing working condition, and provide references for on-site fracturing construction.
And (3) preparing an experimental sample: the temporary plugging test sample needs to be filled with temporary plugging agent at the tip of the preset crack, and the temporary plugging agent is filled at the tip of the crack to finish the sample manufacture on the basis of the manufacture of the three test samples. The experimental sample preparation mainly considers 3 elements: temporary plugging agent type, temporary plugging agent filling amount and temporary plugging agent filling shape.
The temporary plugging agent can be filled in any seam or hole. The types of temporary plugging agents can be classified into particle types and chemical types, and representative temporary plugging agents commonly used at the present stage are fine sand and polymers respectively. While the filling amount of the temporary plugging agent depends on the shape and filling length of the filled seams, holes. For the cracks, the temporary plugging agent is generally filled in the range of 3 mm-20 mm of the joint tip; for holes, the temporary plugging agent is generally filled.
The filling shape of the temporary plugging agent is generally aimed at cracks, and according to experimental requirements, the temporary plugging agent can be filled into a rectangle, a trapezoid, a triangle, a semicircle, a semi-ellipse and the like in a narrow space of a preset crack, and the filling height is between 2 and the thickness of a sample, as shown in fig. 14.
In an embodiment of the present invention, a microscopic visual rock plate hydraulic fracturing indoor simulation apparatus is further provided, and the microscopic visual rock plate hydraulic fracturing indoor simulation method as above is performed by using the simulation apparatus, as shown in fig. 2 to 4, where the microscopic visual rock plate hydraulic fracturing indoor simulation apparatus includes:
The inner part of the outer kettle body is provided with a sealed cylindrical space, the top of the outer kettle body is arranged in a transparent way, a sample seat for placing a sample is arranged in the cylindrical space, and a liquid injection hole is formed in the bottom of the sample seat;
the image acquisition assembly is axially arranged above the outer kettle body and is used for acquiring dynamic images of samples in the outer kettle body in the fracturing process;
the lateral confining pressure hydraulic cylinder and the vertical confining pressure hydraulic cylinder apply loads to the sample along the X direction, the Y direction and the Z direction respectively in the same plane;
and the fluid injection pump is connected with the liquid injection hole through a pipeline and is used for injecting liquid to the sample from the bottom.
In the experimental process, firstly, a prepared experimental sample 8 is placed on a sample seat 10 in an outer kettle body, and fracturing fluid is injected into the sample 8 from the bottom through a pipeline of a fluid injection pump 40; simultaneously, a lateral confining pressure hydraulic cylinder and a vertical confining pressure hydraulic cylinder apply loads to the sample 8 in three directions of an X direction, a Y direction and a Z direction, so that the experimental sample 8 simulates the real reservoir ground stress condition; in addition, the visual monitoring of the dynamic expansion of the hydraulic fracture of the experimental sample 8 under the ground stress condition of the real reservoir can be realized through the image acquisition assembly 24, the dynamic expansion process of the fracture is recorded truly, a new method is provided for the experimental study in the hydraulic fracturing room, and the progress of the hydraulic fracturing experiment to the refinement and visual directions is practically promoted. And the device has reliable design structure, can study the cracking and expanding processes of hydraulic cracks in complex fracture networks and complex fracture-cavity bodies under the three-dimensional ground stress state and the fracturing construction scheme of most unconventional reservoirs in China, and opens up a new idea for the production and study combination in the unconventional reservoir fracturing reconstruction field. In addition, the experimental samples used in the invention have loose requirements on materials and sizes, and experimental staff can select matched components of the experimental frame through the acquired rock samples, so that the hydraulic fracturing simulation experiment of cores with all sizes which can be acquired on site can be satisfied. If the true core cannot be obtained, the experimenter can also select other materials with similar mechanical properties for experiment.
In the embodiment of the invention, as shown in fig. 3, the outer kettle body comprises an outer barrel 7, an upper top cover 2 and a base plate 12 arranged at the top end and the bottom end of the outer barrel 7, and a glass pressing plate 1 arranged on the upper top cover 2, wherein a window opening convenient for observing the inside of the outer kettle body is formed in the center of the upper top cover 2, the glass pressing plate 1 is of an annular plate-shaped structure, an installation groove 15 for embedding window glass 3 is formed in the inner side wall of the glass pressing plate 1 along the circumferential direction, and the window glass 3 coaxially covers the window opening. The upper top cover 2 is provided with a hanging ring mounting screw hole 23 for mounting the hanging ring.
Further, cover connecting screw holes are formed in the outer edge of the glass pressing plate 1 at equal intervals, the cover connecting screw holes are connected with the upper cover 2 through bolts in a fastening mode, a high-speed camera support can be installed in the redundant cover connecting screw holes, a high-speed camera is opposite to the window glass 3, the pressing, cracking and crack extension processes of the experimental sample 8 can be completely recorded, and recorded image data can be used for post-processing analysis. Meanwhile, the outer cylinder 7, the upper top cover 2, the glass pressing plate 1, the window glass 3 and the base plate 12 are combined to form an inner closed cylindrical space for placing a rock sample and other components for fixing, loading and sealing, the support frame 50 is arranged below the base plate 12, and the high-speed camera shooting component is arranged above the upper top cover 2. A plurality of glass pressing plate connecting screw holes are formed in the upper top cover 2 along the circumferential direction, a top cover connecting screw hole is formed in the glass pressing plate 1, and bolts or screws and the like sequentially penetrate through the glass pressing plate connecting screw holes and the top cover connecting screw holes to detachably connect the glass pressing plate 1 with the upper top cover 2.
And the inside of the outer kettle body is a cylindrical hollow space, a circular cavity is formed in the outer kettle body, 4 mutually perpendicular rectangular planes are cut out of the outer kettle body and provided with screw holes for installing 4 mutually perpendicular hydraulic cylinders with piston rods facing the axis of the outer kettle body, and the 4 hydraulic cylinders are installed on the same horizontal plane, so that the loading and unloading of two mutually perpendicular (X, Y) loads can be provided in the horizontal plane. The lower surface of the base plate 12 is provided with screw holes for installing a hydraulic cylinder with a piston rod coincident with the axis of the outer kettle body, so as to provide loading and unloading of load in the direction perpendicular to the plane (Z). A plurality of base plate connecting screw holes are formed in the bottom end wall of the outer cylinder 7 to connect the outer cylinder 7 and the base plate 12 by fasteners. A second outer cylinder connecting screw hole is formed on the glass pressing plate 1 to connect the glass pressing plate 1 with the outer cylinder 7.
Further, as shown in fig. 7, the base plate 12 includes a base body and a base round table 121 disposed at the center of the base body, and a piston rod hole 124 of the vertical confining pressure hydraulic cylinder 13 is formed at the center of the base round table 121 for the piston rod of the vertical confining pressure hydraulic cylinder 13 to penetrate; a plurality of first outer cylinder connecting screw holes 125 are uniformly formed at intervals on the outer edge of the base body so as to be connected with the end wall of the outer cylinder 7 through fasteners; a plurality of vertical confining pressure hydraulic cylinder mounting screw holes 126 are uniformly formed in the outer edge of the base circular table 121 at intervals, so that a cylinder barrel of the vertical confining pressure hydraulic cylinder 13 is mounted at the bottom of the base circular table 121. A liquid injection pipe inlet 122 is formed in the base circular table 121, and a connecting pipeline of the fluid injection pump 40 injects liquid into the sample 8 through the liquid injection pipe inlet 122.
In addition, the window glass 3 is a cylindrical transparent toughened glass plate and is embedded in the glass pressing plate 1; the glass pressing plate 1 is an annular columnar metal plate, a viewing window hole convenient for observation is formed in the glass pressing plate 1, the LED lamp strip 4 is installed on the bottom surface of the glass pressing plate 1, and light can be supplemented for the inner space of the outer kettle body in the experimental process, so that the observation is convenient.
In the embodiment of the present invention, as shown in fig. 6, the sample holder 10 includes a circular base plate 101 and a sample stage 104 installed at the center of the circular base plate 101, and a plurality of rectangular grooves 102 are symmetrically formed in the outer circumference of the circular base plate 101 in the radial direction.
In the embodiment of the invention, the circular chassis 101 is provided with the guide hole 103, the circular chassis 101 and the base plate 12 are coaxially arranged and connected in a guide way through the guide shaft 11, the top end of the guide shaft 11 is arranged on the base plate 12, and the top end of the guide shaft 11 penetrates through and is locked in the guide hole 103.
Specifically, a rectangular experimental sample table 104 is embedded on the circular chassis 101 of the sample holder 10; the surface of the sample table 104 is flat, a plurality of sample liquid injection holes 81 with diameters smaller than 2mm are formed in the direction vertical to the upper surface, and each sample liquid injection hole 81 can be independently opened or closed through a joint or a plug below; the outer edge of the circular chassis 101 is provided with 4 rectangular grooves 102 which are symmetrically distributed, so that the mutual interference between the movement of the sample seat 10 along the Z direction and the piston movement of the piston rod of the hydraulic cylinder in the X and Y directions in the process of loading and unloading is avoided; the base round table 121 is provided with a mounting hole 123 for mounting the guide shaft 11, the round chassis 101 is also provided with a plurality of round guide holes 103 which are symmetrical in center and are matched with the guide shaft 11 fixed on the base plate 12, so that the sample holder 10 is ensured not to deflect in the process of moving along the Z direction.
In the embodiment of the invention, as shown in fig. 2 and 3, the indoor simulation device for hydraulic fracturing of the microscopic visual rock plate further comprises a glass plug 5 with two ends respectively abutting against the window glass 3 and the sample 8, the glass plug 5, the sample 8 and the sample table 104 form a rectangular cylinder together, and a sealing rubber sleeve is sleeved on the outer side wall of the sample 8. The glass plug 5 is a cube-shaped transparent glass block, the upper surface of the glass plug 5 is in contact with the window glass 3, and the lower surface of the glass plug is pressed above the experimental sample 8; the height of the glass plug 5 can be adjusted according to the thickness of the experimental sample 8, and the cross-section size of the glass plug 5 is consistent with the experimental sample 8.
Wherein, transparent sealing sheets are arranged between the sample 8 and the sample table 104 in a sealing way, and the shapes and the sizes of the sample 8, the transparent sealing sheets and the sample table 104 are consistent.
In the embodiment of the invention, as shown in fig. 5, the device further comprises a dislocation loading plate group 9 installed on the sample seat 10, wherein the dislocation loading plate group 9 is of a rectangular frame structure formed by clamping and enclosing four dislocation loading plates 91, and the inner side of the dislocation loading plate group 9 is tightly sealed and adhered to the outer side wall of the sealing rubber sleeve. Wherein, dislocation loading board 91 is an L shape metal part, and limit pin hole 92 has been seted up to the short end of dislocation loading board 91, and limit groove 93,4 dislocation loading board 91 has been seted up to the long end of dislocation loading board 91 places respectively in 4 limits of experimental sample 8, carries out spacingly to experimental sample 8 through the cooperation of pin, limit pin hole 92 and limit groove 93, avoids experimental sample 8 to appear dislocation, the inhomogeneous phenomenon of atress in the loading process.
Further, the inside of the cylindrical hollow space of the outer kettle body is sequentially provided with a glass pressing plate 1, an experimental sample 8 and a sample seat 10 from top to bottom, and transparent sealing sheets for sealing are respectively arranged between the experimental sample 8 and the glass pressing plate 1 and between the experimental sample 8 and the sample seat 10, so that the upper surface and the lower surface of the experimental sample 8 are sealed, and the visibility is ensured; a sealing rubber sleeve is arranged on the outer side of a rectangular cylinder formed by the glass plug 5, the experimental sample 8 and the sample table 104 on the sample seat 10, and the inner surface of the sealing rubber sleeve is tightly attached to the outer surface of the rectangular cylinder. The dislocation loading plate 91 is arranged outside the sealing rubber sleeve, and is matched with the piston rods of the hydraulic cylinders in the X and Y directions to apply uniform load to the experimental sample 8, and the sealing rubber sleeve is compressed while the load is applied, so that the space where the experimental sample 8 is located is completely sealed.
In addition, a hollow support frame 50 is provided at the bottom of the base plate 12 to facilitate the operation of the lower assembly, and the height is greater than that of the vertical confining pressure hydraulic cylinder.
In the embodiment of the invention, the device further comprises a confining pressure pump set 30 for driving the lateral confining pressure hydraulic cylinder 6 and the vertical confining pressure hydraulic cylinder 13 to act, the number of the lateral confining pressure hydraulic cylinders 6 is two, piston rods respectively penetrate through the side wall of the outer cylinder 7 in the X direction and the Y direction in the same plane and are in contact with the outer side wall of the dislocation loading plate 91, and the piston rods of the vertical confining pressure hydraulic cylinders 13 penetrate through the base plate 12 in the Z direction and are in contact with the sample seat 10. The confining pressure pump set 30 comprises 3 three-way confining pressure loading pumps and 1 fluid injection pump 40, wherein the 3 confining pressure loading pumps are respectively connected with 4 hydraulic cylinders in the X direction and the Y direction and 1 hydraulic cylinder in the Z direction through pipelines, and the fluid injection pump 40 is connected with a liquid injection hole 105 joint at the bottom of the sample seat 10 through pipelines.
When the simulation experiment is performed by using the microscopic visual rock plate hydraulic fracturing indoor simulation device, the following examples are taken as illustrations to more clearly understand the operation steps of the simulation device.
Experimental flow for interaction of hydraulic fracture and natural fracture hole
Step one: the lateral confining pressure hydraulic cylinder 6, the vertical confining pressure hydraulic cylinder 13 and the fluid injection pump 40 are assembled, wherein the fluid injection pump 40 is connected with a joint at the lower part of a selected liquid injection hole 105 at the bottom of the sample seat 10 through a pipeline, and the bottoms of the rest liquid injection holes 105 are sealed by plugs;
step two: placing a transparent sealing sheet on a rectangular sample stage 104 of the sample holder 10, and wetting, wherein holes are formed at positions corresponding to liquid injection holes 105 of the sample stage 104;
step three: placing the prepared experimental sample with interaction of the hydraulic fracture and the natural fracture hole on the transparent sealing sheet, wherein the sizes of the sample, the transparent sealing sheet and the sample table 104 are consistent, and the opening positions of the sample, the transparent sealing sheet and the sample table are in one-to-one correspondence, so that the smoothness of the fluid channel is ensured;
step four: placing a transparent sealing sheet for sealing the upper surface of the experimental sample above the sample and wetting, sleeving a rubber sealing sleeve on the outer side of the sample and the sample table 104 from top to bottom, and completing the assembly of the sealing member;
Step five: the dislocation loading plate 91 is sleeved outside the rubber sealing sleeve, so that the inner side corners of the dislocation loading plate are aligned with the outer side corners of the rubber sealing sleeve respectively;
step six: selecting a glass plug 5 with the same size as the experimental sample and proper height, placing the glass plug above the sample, and ensuring that more than 10mm of the lower part of the glass plug 5 is embedded into a rubber sealing sleeve;
step seven: the upper top cover 2 and the glass pressing plate 1 embedded with the window glass 3 are installed, the upper top cover and the glass pressing plate 1 are fastened and connected through bolts, a high-speed camera support and a high-speed camera are installed through redundant screw holes in the glass pressing plate 1, the high-speed camera faces the window glass 3, and the LED lamp strip 4 is opened to supplement a light source;
step eight: starting a lateral confining pressure hydraulic cylinder 6 and a vertical confining pressure hydraulic cylinder 13, applying three-way confining pressure to an experimental sample, and keeping balanced loading of the three-way confining pressure as far as possible, so as to avoid stress concentration in the experimental sample before the experiment;
simultaneous liquid injection
Step nine: all the connectors of all the liquid injection holes 105 at the bottom of the sample holder 10 are communicated, the fluid injection pump 40 is started, pre-prepared experimental fluid is injected, and meanwhile, the high-speed camera is started to record the experimental process completely;
step ten: after the hydraulic fracture penetrates the test sample, the test is ended. After the test is finished, the fluid injection pump 40 is closed, the high-speed camera is closed, the lateral confining pressure hydraulic cylinder 6 and the vertical confining pressure hydraulic cylinder 13 are operated to unload, the high-speed camera frame, the glass pressing plate 1 and the upper top cover 2 are removed from the upper part of the test frame at one time after unloading, and the glass plug 5, the dislocation loading plate 91, the sealing element and the pressed test sample are taken out in sequence;
Step eleven: placing the pressed experimental sample under a microscope, observing crack morphology, crack tip morphology and the like, and performing post-treatment analysis;
step twelve: through the pixel analysis of the high-definition bitmap, 1) researching the path and the slit width change in the dynamic expansion process of the slit, and quantitatively analyzing the dynamic expansion characteristics of the slit; 2) The flow characteristics of the fluid during the dynamic expansion of the fracture are studied in combination with the tracer added to the fluid.
Sequentially injecting liquid
Step nine: the first liquid injection hole 105 at the bottom of the sample holder 10 is communicated according to an experimental scheme, the fluid injection pump 40 is started, pre-prepared experimental fluid is injected, and meanwhile, the high-speed camera is started to record the experimental process completely;
step ten: after the hydraulic fracture penetrates the test sample, the fluid injection pump 40 is turned off, and the next fluid injection hole 105 at the bottom of the sample holder 10 is communicated according to the test scheme to conduct the test.
Step eleven: repeating the step ten, when all the liquid injection holes 105 are sequentially communicated and experiments are completed, closing the injection pump group, operating the lateral confining pressure hydraulic cylinder 6 and the vertical confining pressure hydraulic cylinder 13 to unload, removing the high-speed camera frame, the glass pressing plate 1 and the top cover from the upper part of the experiment frame once after unloading, and sequentially taking out the glass plug 5, the dislocation loading plate 91, the sealing element and the pressed experimental samples;
Step twelve: placing the pressed experimental sample under a microscope, observing crack morphology, crack tip morphology and the like, and performing post-treatment analysis;
step thirteen: through the pixel analysis of the high-definition bitmap, 1) researching the path and the slit width change in the dynamic expansion process of the slit, and quantitatively analyzing the dynamic expansion characteristics of the slit; 2) The flow characteristics of the fluid during the dynamic expansion of the fracture are studied in combination with the tracer added to the fluid.
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (8)
1. An indoor simulation method for micro-visual rock plate hydraulic fracturing is characterized by comprising the following steps of:
Manufacturing an experimental sample provided with a liquid injection hole and a preset crack;
designing parameters of the liquid injection hole and the preset crack, and simulating a complex working condition of hydraulic crack expansion;
presetting a plurality of natural cracks with different forms on the experimental sample, and simulating the initiation and the expansion of hydraulic cracks in a crack body;
presetting a plurality of natural fracture holes with different forms on the experimental sample, and simulating the initiation and the expansion of hydraulic cracks in a fracture hole body;
filling temporary plugging agent at the tip of the preset crack, and simulating the working condition of temporary plugging steering fracturing;
the steps of presetting a plurality of natural cracks with different forms on the experimental sample and simulating the initiation and the extension of the hydraulic cracks in the crack body comprise the following steps:
designing an interaction relation between a preset crack and a natural crack according to the actual working condition in the reservoir;
when the natural fracture is not intersected with the predicted expansion path of the hydraulic fracture, acquiring an influence rule of a stress field under the influence of the natural fracture on the expansion of the hydraulic fracture;
and when the natural fracture intersects with the expected expansion path of the hydraulic fracture, acquiring an interaction rule between the natural fracture and the hydraulic fracture.
2. The method for simulating a microscopic visual rock plate hydraulic fracturing indoor simulation of claim 1, wherein the step of designing parameters of the injection hole and the preset fracture and simulating a complex working condition of hydraulic fracture expansion comprises the following steps:
When the number of the preset cracks is one, acquiring morphological parameters of the hydraulic cracks;
comparing crack initiation and expansion images of the hydraulic cracks under different preset crack forms in a plurality of experimental samples;
and evaluating the influence of the morphological parameters, the three-dimensional stress relation and the injection flow of the preset crack on the crack initiation and expansion according to the comparison result.
3. The method for simulating a microscopic visual rock plate hydraulic fracturing indoor simulation of claim 1, wherein the step of designing parameters of the injection hole and the preset fracture and simulating a complex working condition of hydraulic fracture expansion comprises the following steps:
when the number of the preset cracks is multiple, controlling the liquid injection sequence of the liquid injection holes in the experimental sample so as to simulate the complex working conditions of cracking and expanding of the closely-cut fracturing crack group;
and (3) designing morphological parameters of a plurality of preset cracks in the experimental sample, and obtaining the expansion form of a crack group and the mutual interference rule among a plurality of hydraulic cracks under the closely-cut fracturing working condition.
4. The method for simulating the hydraulic fracturing indoor of the microscopic visual rock plate according to claim 1, wherein the steps of presetting a plurality of natural fracture holes with different forms on the experimental sample and simulating the initiation and the extension of the hydraulic fracture in the fracture hole body comprise the following steps:
Designing an interaction relation between a preset fracture and a natural fracture hole according to the actual working condition in the reservoir;
when the natural fracture hole is not intersected with the predicted expansion path of the hydraulic fracture, acquiring an influence rule of a stress field under the influence of the natural fracture hole on the expansion of the hydraulic fracture;
and when the natural fracture hole is intersected with the expected expansion path of the hydraulic fracture, acquiring an interaction rule between the natural fracture hole and the hydraulic fracture.
5. The microscopic visual rock plate hydraulic fracturing indoor simulation method according to claim 1, wherein the step of filling temporary plugging agent at the tip of the preset crack and simulating temporary plugging steering fracturing working conditions comprises the following steps:
the method comprises the steps of designing morphological parameters of temporary plugging agents in a joint according to actual working conditions and temporary plugging processes in a reservoir;
filling temporary plugging agents of corresponding types and forms at the tips of preset cracks according to the form parameters of the temporary plugging agents;
and obtaining a steering expansion rule of the hydraulic fracture under the corresponding temporary plugging process after the experiment.
6. A microscopic visual rock plate hydraulic fracturing indoor simulation device, wherein the microscopic visual rock plate hydraulic fracturing indoor simulation method according to any one of claims 1 to 5 is performed by using the simulation device, and the microscopic visual rock plate hydraulic fracturing indoor simulation device comprises:
The device comprises an outer kettle body, wherein a sealed cylindrical space is formed in the outer kettle body, a sample seat (10) for placing a sample (8) is arranged in the cylindrical space, a liquid injection hole (105) is formed in the bottom of the sample seat (10), the sample seat (10) comprises a circular base plate (101) and a sample table (104) arranged at the center of the circular base plate (101), a guide hole (103) is formed in the circular base plate (101), the circular base plate (101) and a base plate (12) are coaxially arranged and connected in a guiding manner through a guide shaft (11), the bottom end of the guide shaft (11) is arranged on the base plate (12), and the top end of the guide shaft (11) penetrates through and is locked in the guide hole (103);
the image acquisition assembly is axially arranged above the outer kettle body and is used for acquiring dynamic images of the sample (8) in the outer kettle body in the fracturing process;
a lateral confining pressure hydraulic cylinder (6) and a vertical confining pressure hydraulic cylinder (13) respectively apply load to the sample (8) along the X direction, the Y direction and the Z direction in the same plane;
a fluid injection pump (40) connected to the injection hole (105) through a pipe and used for injecting the sample (8) from the bottom.
7. The microscopic visual rock plate hydraulic fracturing indoor simulation device according to claim 6, wherein the outer kettle body comprises an outer barrel (7), an upper top cover (2) and a base plate (12) which are arranged at the top end and the bottom end of the outer barrel (7), and a glass pressing plate (1) which is arranged on the upper top cover (2), a window which is convenient for observing the inside of the outer kettle body is formed in the center of the upper top cover (2), the glass pressing plate (1) is of an annular plate-shaped structure, an installation groove for embedding window glass (3) is formed in the inner side wall of the glass pressing plate (1) along the circumferential direction, and the window glass (3) is coaxially covered by the window.
8. The indoor simulator of microscopic visual rock plate hydraulic fracturing according to claim 7, further comprising a glass plug (5) with two ends respectively abutting against the window glass (3) and the sample (8) and a dislocation loading plate group (9) installed on the sample seat (10), wherein the glass plug (5), the sample (8) and the sample table (104) jointly form a rectangular cylinder, a sealing rubber sleeve is arranged on the sealing sleeve of the outer side wall of the sample, the dislocation loading plate group (9) is a rectangular frame structure formed by clamping and enclosing four dislocation loading plates (91), and the inner side of the dislocation loading plate group (9) is tightly attached to the outer side wall of the sealing rubber sleeve in a sealing mode.
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Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4830106A (en) * | 1987-12-29 | 1989-05-16 | Mobil Oil Corporation | Simultaneous hydraulic fracturing |
| CN103485759A (en) * | 2013-09-10 | 2014-01-01 | 中国石油大学(北京) | Oil-gas well hydraulically-created-fracture expansion visualization experiment method and oil-gas well hydraulically-created-fracture expansion visualization experiment device |
| CN104060976A (en) * | 2014-07-01 | 2014-09-24 | 中国石油大学(北京) | Method for physically simulating sectional hydrofracture of different well types of perforated well shafts |
| CN105332682A (en) * | 2015-10-21 | 2016-02-17 | 中国石油大学(北京) | Method of experimenting on impact of high-pressure fracture-cave bodies in carbonate rock reservoirs upon hydraulic fracture extension |
| CN105952429A (en) * | 2016-05-17 | 2016-09-21 | 中国地质大学（武汉） | Terrestrial facies shale gas fracture network fracture parameter optimizing method |
| EP3108088A1 (en) * | 2014-02-19 | 2016-12-28 | Repsol, S.A. | Method implemented in a computer for the numerical simulation of a porous medium |
| CN107288604A (en) * | 2017-07-03 | 2017-10-24 | 中国石油大学(北京) | The physical simulation experiment device and its method of the preset intrinsic fracture without medium |
| CN107701160A (en) * | 2017-09-30 | 2018-02-16 | 中国石油大学(华东) | Simulate hydraulically created fracture and the experimental provision and method of intrinsic fracture extension influence |
| CN108386176A (en) * | 2018-01-30 | 2018-08-10 | 中国石油天然气股份有限公司 | Physical model test method for natural crack and artificial crack extension rule |
| CN110500076A (en) * | 2019-07-16 | 2019-11-26 | 李新勇 | It is a kind of for temporarily blocking up the Complex Temporary Blocking method of turnaround fracture |
| CN111911147A (en) * | 2020-08-25 | 2020-11-10 | 中国石油大学(北京) | Testing device and testing method for temporary plugging diversion fracturing |
| CN112343589A (en) * | 2020-11-06 | 2021-02-09 | 武汉大学 | Test method for researching interaction mechanism of hydraulic fracturing complex fracture network microcracks |
| EP3968019A1 (en) * | 2020-09-15 | 2022-03-16 | Liaoning Technical University | Device and method for physical simulation of fracture network propagation based on co-exploitation of three gases of unconventional natural gas |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8972235B2 (en) * | 2012-02-21 | 2015-03-03 | Halliburton Energy Services, Inc. | Methods and systems for subterranean bore hole fracture simulation |
| EP2888441A4 (en) * | 2012-08-24 | 2016-09-14 | Services Petroliers Schlumberger | System and method for performing stimulation operations |
| CN105089657B (en) * | 2015-06-15 | 2018-05-04 | 中国石油天然气股份有限公司 | Physical simulation method and experimental device for oil-gas filling of fracture-cavity carbonate reservoir |
| CN110210144B (en) * | 2019-06-05 | 2019-12-27 | 西南石油大学 | Optimization design method for promoting uniform expansion of horizontal well fracturing fracture by temporary plugging agent |
-
2022
- 2022-04-15 CN CN202210399821.1A patent/CN115370341B/en active Active
Patent Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4830106A (en) * | 1987-12-29 | 1989-05-16 | Mobil Oil Corporation | Simultaneous hydraulic fracturing |
| CN103485759A (en) * | 2013-09-10 | 2014-01-01 | 中国石油大学(北京) | Oil-gas well hydraulically-created-fracture expansion visualization experiment method and oil-gas well hydraulically-created-fracture expansion visualization experiment device |
| EP3108088A1 (en) * | 2014-02-19 | 2016-12-28 | Repsol, S.A. | Method implemented in a computer for the numerical simulation of a porous medium |
| CN104060976A (en) * | 2014-07-01 | 2014-09-24 | 中国石油大学(北京) | Method for physically simulating sectional hydrofracture of different well types of perforated well shafts |
| CN105332682A (en) * | 2015-10-21 | 2016-02-17 | 中国石油大学(北京) | Method of experimenting on impact of high-pressure fracture-cave bodies in carbonate rock reservoirs upon hydraulic fracture extension |
| CN105952429A (en) * | 2016-05-17 | 2016-09-21 | 中国地质大学（武汉） | Terrestrial facies shale gas fracture network fracture parameter optimizing method |
| CN107288604A (en) * | 2017-07-03 | 2017-10-24 | 中国石油大学(北京) | The physical simulation experiment device and its method of the preset intrinsic fracture without medium |
| CN107701160A (en) * | 2017-09-30 | 2018-02-16 | 中国石油大学(华东) | Simulate hydraulically created fracture and the experimental provision and method of intrinsic fracture extension influence |
| CN108386176A (en) * | 2018-01-30 | 2018-08-10 | 中国石油天然气股份有限公司 | Physical model test method for natural crack and artificial crack extension rule |
| CN110500076A (en) * | 2019-07-16 | 2019-11-26 | 李新勇 | It is a kind of for temporarily blocking up the Complex Temporary Blocking method of turnaround fracture |
| CN111911147A (en) * | 2020-08-25 | 2020-11-10 | 中国石油大学(北京) | Testing device and testing method for temporary plugging diversion fracturing |
| EP3968019A1 (en) * | 2020-09-15 | 2022-03-16 | Liaoning Technical University | Device and method for physical simulation of fracture network propagation based on co-exploitation of three gases of unconventional natural gas |
| CN112343589A (en) * | 2020-11-06 | 2021-02-09 | 武汉大学 | Test method for researching interaction mechanism of hydraulic fracturing complex fracture network microcracks |
Non-Patent Citations (2)
| Title |
|---|
| 缝洞型碳酸盐岩储层压裂效果评价方法试验研究;李新勇等;石油钻探技术;全文 * |
| 页岩暂堵转向压裂水力裂缝扩展物模试验研究;侯冰等;辽宁石油化工大学学报;全文 * |
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