CN115370341A - Microscopic visual rock plate hydraulic fracturing indoor simulation method and device - Google Patents
Microscopic visual rock plate hydraulic fracturing indoor simulation method and device Download PDFInfo
- Publication number
- CN115370341A CN115370341A CN202210399821.1A CN202210399821A CN115370341A CN 115370341 A CN115370341 A CN 115370341A CN 202210399821 A CN202210399821 A CN 202210399821A CN 115370341 A CN115370341 A CN 115370341A
- Authority
- CN
- China
- Prior art keywords
- fracture
- hydraulic
- sample
- preset
- expansion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 90
- 239000011435 rock Substances 0.000 title claims abstract description 52
- 238000004088 simulation Methods 0.000 title claims abstract description 50
- 230000000007 visual effect Effects 0.000 title claims abstract description 19
- 238000002347 injection Methods 0.000 claims abstract description 74
- 239000007924 injection Substances 0.000 claims abstract description 74
- 239000007788 liquid Substances 0.000 claims abstract description 55
- 238000002474 experimental method Methods 0.000 claims abstract description 47
- 230000008569 process Effects 0.000 claims abstract description 45
- 230000000977 initiatory effect Effects 0.000 claims abstract description 37
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 34
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- 239000011521 glass Substances 0.000 claims description 47
- 238000007789 sealing Methods 0.000 claims description 35
- 238000003825 pressing Methods 0.000 claims description 25
- 238000012800 visualization Methods 0.000 claims description 25
- 239000012530 fluid Substances 0.000 claims description 23
- 230000000877 morphologic effect Effects 0.000 claims description 17
- 239000005357 flat glass Substances 0.000 claims description 15
- 230000003993 interaction Effects 0.000 claims description 15
- 230000002452 interceptive effect Effects 0.000 claims description 6
- 238000005520 cutting process Methods 0.000 claims description 5
- 238000009434 installation Methods 0.000 claims description 3
- 238000011160 research Methods 0.000 abstract description 10
- 238000011002 quantification Methods 0.000 abstract description 3
- 206010017076 Fracture Diseases 0.000 description 221
- 208000010392 Bone Fractures Diseases 0.000 description 177
- 238000010276 construction Methods 0.000 description 12
- 238000002360 preparation method Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 208000006670 Multiple fractures Diseases 0.000 description 2
- 239000011796 hollow space material Substances 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000012805 post-processing Methods 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 239000000700 radioactive tracer Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000009736 wetting Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000002981 blocking agent Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 238000001454 recorded image Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000005341 toughened glass Substances 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
Abstract
The invention provides a microcosmic visual indoor simulation method and device for hydraulic fracturing of a rock plate, wherein the method comprises the steps of manufacturing an experimental sample provided with a liquid injection hole and a preset crack; acquiring parameters of a liquid injection hole and a preset crack, and simulating a complex working condition of hydraulic crack expansion; presetting a plurality of natural fractures with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture body; presetting a plurality of natural fracture holes with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture hole body; and filling a temporary plugging agent at the tip of the preset crack, and simulating a temporary plugging steering fracturing working condition. The microcosmic visualized rock plate hydraulic fracturing indoor simulation method can visually monitor the dynamic expansion rule of the hydraulic fracture under the real reservoir stratum crustal stress condition, record the dynamic expansion process of the fracture in real time, provide a new method for the hydraulic fracturing indoor experimental research, 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 oil and gas reservoir hydraulic fracturing development, and particularly relates to a microcosmic visual rock plate hydraulic fracturing indoor simulation method and device.
Background
The reserves of unconventional oil and gas resources in China are huge, and hydraulic fracturing is the most common reservoir transformation process for efficiently developing the unconventional oil and gas resources at present. The large-scale volume fracturing is carried out through the horizontal well and the multistage fracturing, a large number of hydraulic fractures can be formed in an unconventional reservoir, the drainage area of the reservoir is greatly increased, and a large number of oil and gas migration channels with high flow conductivity are formed, so that the unconventional oil and gas exploitation conditions are greatly improved, and the recovery ratio is improved.
With the successful application of hydraulic fracturing in the field of unconventional oil and gas and the increasing difficulty of unconventional oil and gas exploitation year by year, higher requirements are put forward on a research method of a hydraulic fracturing fracture propagation mechanism. In order to provide powerful and reliable technical support for on-site fracturing design and construction schemes through experimental research, more visual, quantitative and diversified experimental methods need to be provided for indoor experiments of hydraulic fracturing on the basis of simulating the ground stress state of a real stratum, the traditional hydraulic fracturing experiments are 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 the temporary plugging process is adopted, the quantitative analysis on the form of the hydraulic fracture is difficult to carry out after the experiments are 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 a microcosmic visual rock hydraulic fracturing indoor simulation method and device, and aims to solve the technical problem that the microcosmic visual rock hydraulic fracturing indoor simulation method in the prior art cannot intuitively reflect quantitative dynamic change parameters of hydraulic fractures.
In order to achieve the purpose, the invention provides a microscopic visual rock plate hydraulic fracturing indoor simulation method, which comprises the following steps:
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 fractures with different forms on the experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture body;
presetting a plurality of natural fracture holes with different forms on the experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture hole body;
and filling a temporary plugging agent at the tip of the preset crack, and simulating the working condition of temporary plugging and steering fracturing.
In the embodiment of the invention, the step of designing the parameters of the liquid injection hole and the preset fracture and simulating the complex working condition of hydraulic fracture propagation comprises the following steps:
when the number of the preset fractures is one, acquiring morphological parameters of the hydraulic fractures;
comparing fracture initiation and expansion images of the hydraulic fracture under different preset fracture forms in a plurality of experimental samples;
and evaluating the influence of the morphological parameters, the three-way stress relation and the injection flow of the preset fracture on the fracture initiation and expansion according to the comparison result.
In the embodiment of the invention, the step of designing the parameters of the liquid injection hole and the preset fracture and simulating the complex working condition of hydraulic fracture propagation comprises the following steps:
when the number of the preset cracks is multiple, controlling the liquid injection sequence of a plurality of liquid injection holes in the experimental sample so as to simulate the complex working conditions of initiation and expansion of the close cut fracture group;
morphological parameters of a plurality of preset fractures in an experimental sample are designed, and the expansion morphology of a fracture group and the mutual interference rule among a plurality of hydraulic fractures under the close cutting fracturing working condition are obtained.
In an embodiment of the present invention, the steps of presetting a plurality of natural fractures with different morphologies on the experimental sample and simulating the initiation and propagation of a hydraulic fracture in a fracture body include:
designing an interactive relation between a preset fracture and a natural fracture according to actual working conditions in a reservoir;
when the natural fracture and the predicted expansion path of the hydraulic fracture do not intersect, acquiring the 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 predicted propagation 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 morphologies on the experimental sample and simulating the initiation and propagation of the hydraulic fracture in the fracture hole body comprise:
designing an interactive relation between a preset crack and a natural fracture hole according to the actual working condition in a reservoir;
when the natural fracture-cave does not intersect with the predicted expansion path of the hydraulic fracture, acquiring the influence rule of a stress field under the influence of the natural fracture-cave on the expansion of the hydraulic fracture;
and when the natural fracture-cave intersects with the predicted propagation path of the hydraulic fracture, acquiring an interaction rule between the natural fracture-cave and the hydraulic fracture.
In an embodiment of the invention, the step of filling the temporary plugging agent at the tip of the preset fracture and simulating the temporary plugging steering fracturing condition comprises the following steps:
designing morphological parameters of the temporary plugging agent in the seam according to the actual working conditions and the temporary plugging process in the reservoir;
filling temporary plugging agents of corresponding types and forms at the tips of the preset cracks according to the form parameters of the temporary plugging agents;
and obtaining the 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 visualized rock hydraulic fracturing indoor simulation device is further provided, where the microscopic visualized rock hydraulic fracturing indoor simulation method is performed by using the simulation device, and the microscopic visualized rock hydraulic fracturing indoor simulation device includes:
the device comprises an outer kettle body, a liquid storage tank, a liquid inlet pipe, a liquid outlet pipe, a liquid inlet pipe, a liquid outlet pipe and a liquid outlet pipe, wherein a closed cylindrical space is formed inside the outer kettle body, 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 a dynamic image of a sample in the outer kettle body in a fracturing process;
the lateral confining pressure hydraulic cylinder and the vertical confining pressure hydraulic cylinder respectively apply loads to the sample along the X direction, the Y direction and the Z direction in the same plane;
and the fluid injection pump is connected with the injection hole through a pipeline and is used for injecting the sample from the bottom.
In the embodiment of the invention, the outer kettle body comprises an outer cylinder, an upper top cover and a base plate which are arranged at the top end and the bottom end of the outer cylinder, and a glass pressing plate arranged on the upper top cover, wherein a viewing window convenient for observing the inside of the outer kettle body is arranged in the center of the upper top cover, the glass pressing plate is of an annular plate-shaped structure, an installation groove for embedding viewing window glass is formed in the inner side wall of the glass pressing plate along the circumferential direction, and the viewing window is coaxially covered by the viewing window glass.
In the embodiment of the invention, the sample seat comprises a circular base plate and a sample platform arranged at the center of the circular base plate, a guide hole is formed in the circular base plate, the circular base plate and the base plate are coaxially arranged and are in guide connection through a guide shaft, the bottom end of the guide shaft is arranged on the base plate seat, and the top end of the guide shaft penetrates through and is locked in the guide hole.
In an embodiment of the invention, the visual rock plate dynamic fracture experimental device further comprises a glass plug of which two ends are respectively abutted against the window glass and the sample, and a staggered loading plate group arranged on the sample seat, wherein the glass plug, the sample and the sample platform jointly form a rectangular cylinder, a sealing rubber sleeve is sleeved on the outer side wall of the sample in a sealing manner, the staggered loading plate group is a rectangular frame structure formed by enclosing four staggered loading plate joints, and the inner side of the staggered loading plate group is tightly attached to the outer side wall of the sealing rubber sleeve in a sealing manner.
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; acquiring parameters of a liquid injection hole and a preset crack, and simulating a complex working condition of hydraulic crack expansion; presetting a plurality of natural fractures with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture body; presetting a plurality of natural fracture holes with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture hole body; filling a temporary plugging agent at the tip of a preset crack, and simulating a temporary plugging steering fracturing working condition; the invention can realize the visual monitoring of the dynamic expansion of the hydraulic fracture of the experimental sample under the real reservoir stratum crustal stress condition, and the dynamic expansion process of the fracture is recorded really, thereby providing a new method for the experimental research in a hydraulic fracturing chamber, promoting the progress of the hydraulic fracturing experiment to the refinement and quantification direction practically, and greatly expanding 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, which are included to provide an understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a schematic flow diagram of a microscopic visualization rock hydraulic fracturing indoor simulation method according to an embodiment of the invention;
FIG. 2 is a schematic diagram of an assembly structure of the microscopic visualization rock plate hydraulic fracturing indoor simulation device according to an embodiment of the invention;
FIG. 3 is a schematic diagram of a partial structure of a microscopic visualization rock hydraulic fracturing indoor simulation device according to an embodiment of the invention;
FIG. 4 is a schematic view, partially in section, of a microscopic visualization rock plate hydraulic fracturing indoor simulation apparatus in accordance with an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a staggered loading plate group in a microscopic visualization rock hydraulic fracturing indoor simulation device according to an embodiment of the invention;
FIG. 6 is a schematic diagram of a sample holder in a microscopic visualization rock hydraulic fracturing indoor simulation device according to an embodiment of the invention;
FIG. 7 is a schematic structural diagram of a base plate in the microscopic visualization rock hydraulic fracturing indoor simulation device according to an embodiment of the invention;
FIG. 8 is a schematic structural diagram of an experimental sample in an indoor simulation apparatus for microscopic visualization of hydraulic fracturing of a rock plate according to an embodiment of the invention;
FIG. 9 is a schematic diagram of pre-set fracture morphology parameters of experimental samples in a microscopic visualization indoor simulation method for hydraulic fracturing of a rock plate according to an embodiment of the invention;
FIG. 10 is a schematic view of the stress loading of the experimental sample in the microscopic visualization indoor simulation method for hydraulic fracturing of a rock plate according to 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 visualization indoor simulation of hydraulic fracturing of a rock panel in accordance with an embodiment of the present invention;
FIG. 12 is a schematic illustration of the location and morphology of natural fracture holes of experimental samples in a microscopic visualization indoor simulation method of hydraulic fracturing of rock panels according to an embodiment of the present invention;
FIG. 13 is a scanning electron micrograph of the interaction of hydraulic fractures and natural cavities in a real rock plate;
fig. 14 is a schematic view of the filling position and filling form of the temporary plugging agent in the experimental sample according to an embodiment of the present invention;
FIG. 15 is a scanning electron micrograph of an experimental sample after being filled with a temporary blocking agent according to an embodiment of the present invention;
fig. 16 is a morphological schematic diagram illustrating mutual interference of a plurality of hydraulic fractures in a microscopic visualization rock hydraulic fracturing indoor simulation method according to an embodiment of the invention.
Description of the reference numerals
Detailed Description
The following detailed description of specific embodiments of the invention refers to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and explanatory of the invention and are not restrictive thereof.
The microscopic visualization rock plate hydraulic fracturing indoor simulation method according to the invention is described below with reference to the drawings.
As shown in fig. 1, in an embodiment of the invention, there is provided a microscopic visualization 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 fractures with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture body;
step S40: presetting a plurality of natural fracture holes with different forms on an experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture hole body;
step S50: and filling a temporary plugging agent at the tip of the preset crack, and simulating a temporary plugging steering fracturing working condition.
It should be noted that the original existing fractures in the sample before the experiment are called as preset fractures, and the purpose is to guide the fracture initiation position and direction of the fractures propped by the water pressure in the experiment process. The fractures propped open by the water pressure after the experiment are called hydraulic fractures. In this context, to distinguish between two fractures, a pre-set fracture and a hydraulic fracture may be identified.
The experimental sample size in the microscopic visual rock plate hydraulic fracturing indoor simulation experiment is small, and the designed injection displacement range is 0-20 mL/min; the confining pressure loading range is 0-20 MPa; according to a similar theory, the ground stress state and the fracturing construction parameters of most unconventional reservoirs in China can be simulated. Specifically, the used experimental sample is in a rectangular sheet shape, the side length of the sample is 50-70 mm, the thickness of the sample is 3-20 mm, the material of the sample can be underground rock core, outcrop rock sample, artificial rock sample and other samples formed by cutting materials, and the size can meet the requirements.
The method can realize the visual monitoring of the dynamic expansion of the hydraulic fracture of the experimental sample under the real reservoir stratum crustal stress condition, the dynamic expansion process of the fracture is really recorded, and more visual, quantitative and dynamic parameters related to the hydraulic fracture can be obtained through post-processing based on visual materials, and the method comprises the following steps: 1) dynamic recording of a fracture propagation path, 2) quantitative dynamic change recording of fracture width, 3) flow characteristics of fluid in a fracture dynamic propagation process, 4) interaction between particle minerals and lithologic interfaces and natural fractures and hydraulic fractures, and 5) real stress and deformation characteristics of fracture tips.
The invention provides five forms of simulating hydraulic fractures under the ground stress condition of a real reservoir, 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 experiment, provides a new method for the research of hydraulic fracturing indoor experiments, practically promotes the progress of the hydraulic fracturing experiment to the direction of refinement and quantification, and greatly expands the research method of the hydraulic fracturing experiment.
In the embodiment of the invention, the step of designing the parameters of the liquid injection hole and the preset fracture and simulating the complex working condition of hydraulic fracture propagation comprises the following steps:
when the number of the preset cracks is one, acquiring morphological parameters of the hydraulic cracks;
comparing fracture initiation and expansion images of the hydraulic fracture under different preset fracture forms in a plurality of experimental samples;
and evaluating the influence of the morphological parameters, the three-way stress relation and the injection flow of the preset fracture on the fracture initiation and expansion according to the comparison result.
Further, in the steps of the simulation method, experimental sample preparation mainly considers 2 elements under satisfying the above-mentioned size and material conditions: the position of a sample injection hole and the shape of a preset sample crack.
The liquid injection hole of the hydraulic fracture propagation experiment can be arranged in the middle or at the edge of the sample, as shown in the left two figures in fig. 9, when the liquid injection hole is arranged in the middle, the propagation of the double-wing fracture can be simulated, but the fracture propagation path is relatively short; when the liquid injection hole is arranged at the edge, the expansion of the single wing crack is simulated, the crack expansion path is relatively long, and the observation of the far-end form of the hydraulic crack is facilitated.
The preset crack can be selected or not preset when a sample is processed, the preset crack can play a role in controlling the crack initiation position and guiding the crack initiation direction, 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 to be between 5mm and 20mm, the crack width w is generally controlled to be between 0.1mm and 3mm, and the deflection angle theta can be set to be between-90 degrees and 90 degrees, as shown in the rightmost diagram in figure 9. Different seam lengths can be used for researching the influence of the stress condition of the seam tip on the crack initiation and expansion under the same injection condition; different seam widths can be used for researching the influence of the shape (curvature) of the seam point on the crack initiation and expansion; different deflection angles can be used to study the effect of different initiation directions on fracture initiation and propagation.
In the embodiment of the invention, the step of designing the parameters of the liquid injection hole and the preset crack and simulating the complex working condition of hydraulic crack propagation comprises the following steps:
when the number of the preset cracks is multiple, controlling the liquid injection sequence of a plurality of liquid injection holes in the experimental sample so as to simulate the complex working conditions of initiation and expansion of the close cut fracture group;
and (3) designing morphological parameters of a plurality of preset fractures in the experimental sample, and acquiring the expansion morphology of the fracture group and the mutual interference rule among a plurality of hydraulic fractures under the close cutting and fracturing working condition.
In petroleum engineering, tight fracture can be intuitively understood as the propagation of multiple fractures initiated simultaneously or sequentially. The multiple fractures under the tight-cutting fracturing working condition are called as fracture groups in an image mode.
The simulation experiment method of the step is mainly used for simulating the problem of the interference between the cracks in the field fracturing process. In the field fracturing process, under the fracturing design scheme of difference, the condition that many cracks expand simultaneously in certain spatial dimension can often appear, under this kind of condition, can produce induced stress between the crack (also be that every seam all can strut the stratum, this power of strutting is exactly induced stress in the deformation of stratum rock), and induced stress can make many hydraulic fracture extrude each other for crack extension route and direction change. The process is simplified in the experiment, different working conditions are simulated by controlling the parameters of the preset cracks and the liquid injection sequence of the liquid injection hole, the construction parameters are optimized by simulating the complex working conditions of competitive expansion of multiple cracks, and reference is provided for the fracturing construction on site.
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 the conventional crack propagation experiment, and 3 factors are mainly considered: the positions and the number of the liquid injection holes, the preset natural crack form and the simultaneous or sequential liquid injection of a plurality of liquid injection holes in the experimental process.
In order to fully observe the mutual interference process of a plurality of hydraulic fractures, a liquid injection hole is generally arranged at the edge of an experimental sample, so that each hydraulic fracture has a sufficient expansion space; the number of the injection holes is generally 2-10, depending on the size of the sample to be tested, as shown in the left side of the graph in FIG. 16.
When a sample is processed, each liquid injection hole can be selected to preset or not preset a crack, the morphological parameters of the preset crack comprise the length L of the crack, the width w of the crack and the deflection angle theta, the control range of the morphological parameters of the crack is consistent with the sample preparation requirement of a conventional crack propagation experiment, and the mutual interference phenomenon among hydraulic cracks under different working conditions can be researched by setting different morphological parameters of the crack, as shown in a right picture shown in figure 16.
According to the design of experimental scheme, can through annotating the liquid hole joint switch-on or sealing operation to a plurality of sample seat bottoms portion, realize a plurality of notes liquid holes and annotate liquid simultaneously or in proper order, satisfy the indoor simulation experiment of hydraulic fracture mutual interference under the complicated operating mode.
In the embodiment of the invention, the steps of presetting a plurality of natural fractures with different forms on an experimental sample and simulating the initiation and the propagation of hydraulic fractures in a fracture body comprise the following steps:
designing an interactive relation between a preset fracture and a natural fracture according to actual working conditions in a reservoir;
when the natural fracture and the expected expansion path of the hydraulic fracture do not intersect, acquiring the influence rule of a stress field under the influence of the natural fracture on the expansion of the hydraulic fracture;
and acquiring the interaction influence rule between the natural fracture and the hydraulic fracture when the natural fracture and the predicted propagation path of the hydraulic fracture intersect.
Preparing an experimental sample: the experimental sample preparation mainly considers 2 elements on the basis of meeting the sample preparation requirement of the conventional crack propagation experiment: the pre-set location of the natural fracture and the pre-set natural fracture morphology.
The natural crack can be preset at any position in an experimental sample, a plurality of natural cracks with different positions and forms can be preset in one experimental sample according to needs, and the intersection angle alpha of the natural crack and the hydraulic crack can be set to be 0-90 degrees.
The method is characterized in that natural fractures which are not intersected with the expected expansion path of the hydraulic fracture are preset in a sample, in the experimental process, after a preset load is loaded, the sample can be subjected to non-uniform deformation due to the existence of the natural fractures, a non-uniform stress field is further formed, in the hydraulic fracture expansion process, the non-uniform stress field can influence the expansion direction and the path of the hydraulic fracture, and the method can be used for researching the influence of the stress field under the influence of the natural fractures on the expansion of the hydraulic fracture.
The natural fracture intersected with the predicted propagation path of the hydraulic fracture is preset in the sample, and the hydraulic fracture has 2 in the experimental processAnd one or more propagation paths, wherein the hydraulic fracture can be propagated in different directions according to the ground stress condition and the change of the intersection angle alpha of the natural fracture and the hydraulic fracture. Can be used for researching the interaction between the hydraulic fracture and the natural fracture. The two methods for presetting natural fractures are combined to simulate the expansion process of hydraulic fractures in a complex fracture body of a real stratum. The positions where the natural fractures can be preset, the optional forms of the preset natural fractures, and the preset single natural fracture with an included angle of 30 degrees with the hydraulic fracture are sequentially shown from left to right in fig. 9. The stress loading of the experimental samples is shown in FIG. 10, where σ H Is the maximum horizontal principal stress, σ h Is the minimum level principal stress, σ v Is the overburden stress. This experiment was mainly studied to influence sigma H And σ h The effect on the crack propagation direction and path. Sigma H ≥σ h Theoretical hydraulic fracture edge σ H Direction propagation, so hydraulic fracture is generally perpendicular to σ h The preset natural fracture and the hydraulic fracture form a certain included angle.
The experiment aims to optimize the pertinence construction parameters of the fracture body with different occurrence states by simulating the initiation and the expansion of the hydraulic fracture in the fracture body, and provide reference for the on-site fracturing construction.
The length of the preset natural crack is generally more than 5mm, the longest natural crack does not penetrate through an experimental sample, the width of the natural crack is generally controlled to be 0.1-3 mm, and as shown in fig. 11, the natural crack can be in a linear type, a broken line type, a curve type or other irregular shapes.
In the embodiment of the invention, the steps of presetting a plurality of natural fracture holes with different forms on the experimental sample and simulating the initiation and the propagation of the hydraulic fracture in the fracture hole body comprise:
designing an interactive relation between a preset crack and a natural fracture hole according to the actual working condition in a reservoir;
when the natural fracture-cave does not intersect with the expected expansion path of the hydraulic fracture, acquiring the influence rule of a stress field under the influence of the natural fracture-cave on the expansion of the hydraulic fracture;
and when the natural fracture-cave intersects with the predicted propagation path of the hydraulic fracture, acquiring an interaction rule between the natural fracture-cave and the hydraulic fracture.
Preparing an experimental sample: the experimental sample preparation mainly considers 2 elements on the basis of meeting the sample preparation requirement of the conventional crack propagation experiment: 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 sample, and a plurality of natural seam holes with different positions and forms can be preset in one experimental sample according to the requirement.
As shown in fig. 13, a natural fracture not intersecting with the expected propagation path of the hydraulic fracture is preset in the sample, and in the experimental process, after a predetermined load is loaded, the natural fracture causes the sample to be deformed non-uniformly, so that a non-uniform stress field is formed, and in the process of hydraulic fracture propagation, the non-uniform stress field affects the propagation direction and path of the hydraulic fracture, and the method can be used for researching the influence of the stress field under the influence of the natural fracture on the hydraulic fracture propagation.
The method comprises the steps of presetting a natural fracture hole intersected with an expected extension path of the hydraulic fracture in a sample, stopping extension temporarily after the hydraulic fracture meets a fracture body in the experimental process, filling high-pressure fluid into the fracture body, enabling the hydraulic fracture to be re-cracked and extended from a weak point of the fracture body along with the increase of pressure in the fracture body, and enabling the hydraulic fracture to select different paths to extend along with the change of ground stress conditions and the shape of the fracture body. The method can be used for researching the interaction between the hydraulic fracture and the natural fracture and cave; the method for presetting natural fractures is combined to simulate the expansion process of hydraulic fractures in a complex fracture-cavity body of a real stratum.
The left and middle panels of fig. 11 show the locations where the natural holes can be placed, and the right-most panel of fig. 11 shows an alternative configuration for placing natural holes.
The experiment aims to optimize the pertinence construction parameters of the fracture-cavity body with different production states by simulating the initiation and the expansion of hydraulic fractures in the fracture-cavity body, and provide reference for the on-site fracturing construction.
Length D of preset natural seam hole long shaft 1 Generally controlled between 0.5 mm and 20mm, does not penetrate through the experimental sample, and the natural slot shape can be circular, oval or ellipticalOther irregular shapes, see the right-most drawing of fig. 12.
In an embodiment of the invention, the step of filling a temporary plugging agent at the tip of the preset fracture and simulating a temporary plugging diversion fracturing working condition comprises the following steps:
designing morphological parameters of the temporary plugging agent in the seam according to the actual working conditions and the temporary plugging process in the reservoir;
filling temporary plugging agents of corresponding types and forms at the tips of the preset cracks according to the form parameters of the temporary plugging agents;
and obtaining the turning and expanding rule of the hydraulic fracture under the corresponding temporary plugging process after the experiment.
In the hydraulic fracturing field construction process, the results of small crack spread range and poor reservoir transformation effect caused by single crack form exist. Therefore, in order to increase the complexity of the crack propagation path and increase the crack spread range, the 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, and the crack is diverted from the weak part of the existing crack surface to propagate. The experimental method is used for simulating the oilfield field construction scheme and observing the expansion rule of the crack under different temporary plugging conditions. The experiment aims to optimize pump injection parameters, optimize the type of the temporary plugging agent and optimize the filling amount of the temporary plugging agent by simulating the temporary plugging diverting fracturing working condition, and provide reference for on-site fracturing construction.
Preparing an experimental sample: and (3) filling a temporary plugging agent at the tip of a preset crack in the temporary plugging experiment sample, and filling the temporary plugging agent at the tip of the crack to finish the sample preparation on the basis of the preparation of the three experiment samples. Experimental sample preparation mainly takes 3 factors into consideration: the type of the temporary plugging agent, the filling amount of the temporary plugging agent and the filling shape of the temporary plugging agent.
The temporary plugging agent can be filled in any seam or hole. The types of temporary plugging agents can be divided into particle type and chemical type, and representative temporary plugging agents commonly used at present are fine sand and polymer respectively. And the filling amount of the temporary plugging agent depends on the shape and filling length of the filled seams and holes. For cracks, the temporary plugging agent is generally filled in the range of 3 mm-20 mm of the crack tip; for holes, the temporary plugging agent is typically filled.
The filling shape of the temporary plugging agent is generally specific to cracks, and according to experimental needs, the temporary plugging agent can be filled into a rectangular shape, a trapezoidal shape, a triangular shape, a semicircular shape, a semi-elliptical shape and the like in a narrow space where the cracks are preset, wherein the filling height is 2-sample thickness, and is shown in fig. 14.
In an embodiment of the present invention, a microscopic visualized rock plate hydraulic fracturing indoor simulation device is further provided, and the above microscopic visualized rock plate hydraulic fracturing indoor simulation method is performed by using the simulation device, as shown in fig. 2 to 4, and the microscopic visualized rock plate hydraulic fracturing indoor simulation device includes:
the inner part of the outer kettle body is provided with a closed 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 the bottom of the sample seat is provided with a liquid injection hole;
the image acquisition assembly is axially arranged above the outer kettle body and is used for acquiring a dynamic image of a sample in the outer kettle body in a fracturing process;
the lateral confining pressure hydraulic cylinder and the vertical confining pressure hydraulic cylinder respectively apply loads to the sample along the X direction, the Y direction and the Z direction in the same plane;
and the fluid injection pump is connected with the injection hole through a pipeline and is used for injecting the sample from the bottom.
In the experiment process, firstly, a prepared experiment 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; meanwhile, the lateral confining pressure hydraulic cylinder and the vertical confining pressure hydraulic cylinder apply loads to the sample 8 in the X direction, the Y direction and the Z direction, so that the experimental sample 8 can simulate the ground stress condition of a real reservoir; in addition, the invention can realize the visual monitoring of the dynamic expansion of the hydraulic fracture of the experimental sample 8 under the real reservoir stratum ground stress condition through the image acquisition assembly 24, and really record the dynamic expansion process of the fracture, thereby providing a new method for the indoor experimental research of the hydraulic fracturing and practically promoting the progress of the hydraulic fracturing experiment to the refinement and visualization direction. Moreover, the device is reliable in design structure, can study the fracture initiation and expansion processes of hydraulic fractures in complex fracture nets and complex fracture-cavity bodies under most unconventional reservoir three-dimensional ground stress states and fracturing construction schemes in China, and develops a new idea for the combination of production and study in the field of unconventional reservoir fracturing modification. In addition, the requirements of the experimental sample on the material and the size are relaxed, and an experimenter can select a matching component of the experimental frame through the obtained rock sample, so that the hydraulic fracturing simulation experiment of cores with all sizes, which can be obtained on site, can be met. If the real 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 cylinder 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 cylinder 7, and a glass pressing plate 1 which is arranged on the upper top cover 2, wherein a viewing window which is convenient for observing the inside of the outer kettle body is arranged at the center of the upper top cover 2, the glass pressing plate 1 is in an annular plate-shaped structure, an installation groove 15 for embedding the viewing window glass 3 is formed in the inner side wall of the glass pressing plate 1 along the circumferential direction, and the viewing window glass 3 coaxially covers the viewing window. And a hanging ring mounting screw hole 23 is formed in the upper top cover 2 and used for mounting a hanging ring.
Furthermore, top cover connecting screw holes are distributed on the outer edge of the glass pressing plate 1 at equal intervals, except for being fastened and connected with the upper top cover 2 through bolts, a high-speed camera support can be installed on redundant top cover connecting screw holes, a high-speed camera is opposite to the window glass 3, the processes of pressure building, crack initiation and crack expansion of the experimental sample 8 can be completely recorded, and recorded image data can be used for post-processing analysis. Meanwhile, the outer barrel 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 rock samples and other components for fixing, loading and sealing, the support frame 50 is installed below the base plate 12, and the high-speed camera shooting component is installed 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, top cover connecting screw holes are formed in the glass pressing plate 1, and bolts or screws 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 and the upper top cover 2.
And, the internal portion of outer cauldron is cylindrical hollow space and inside forms circular cavity, cuts 4 mutually perpendicular rectangle planes and opens and have the screw outside the outer cauldron body for install 4 mutually perpendicular and the piston rod all towards the pneumatic cylinder of outer cauldron body axis, 4 pneumatic cylinders are installed in same horizontal plane, can provide the loading and the uninstallation of two mutually perpendicular (X, Y) direction loads in this horizontal plane. The lower surface of the base plate 12 is provided with screw holes for mounting hydraulic cylinders with piston rods coinciding with the axis of the outer vessel, which can provide loading and unloading of loads in the direction perpendicular to the plane (Z). A plurality of bed plate coupling screw holes are formed in the bottom end wall of the outer tub 7 to couple the outer tub 7 and the bed plate 12 by fastening members. The glass pressing plate 1 is provided with a second outer cylinder connecting screw hole so as to connect the glass pressing plate 1 and the outer cylinder 7.
Further, as shown in fig. 7, the base plate 12 includes a base body and a base circular table 1 disposed at the center of the base body, and a piston rod hole 124 of the vertical confining pressure hydraulic cylinder 13, through which a piston rod of the vertical confining pressure hydraulic cylinder 13 passes, is disposed at the center of the base circular table 1; a plurality of first outer cylinder body 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 body 7 through fasteners; a plurality of vertical confining pressure hydraulic cylinder 13 mounting screw holes 126 are further uniformly formed in the outer edge of the base circular table 1 at intervals so as to mount the cylinder barrel of the vertical confining pressure hydraulic cylinder 13 at the bottom of the base circular table 1. A liquid injection pipe inlet 1 is formed in the circular truncated cone 1 of the base, and a connecting pipeline of the fluid injection pump 40 injects a sample 8 through the liquid injection pipe inlet 1.
In addition, the window glass 3 is a cylindrical transparent toughened glass plate and is embedded in the glass pressing plate 1; glass clamp plate 1 is an annular column metal sheet, sets up the window hole of being convenient for observe on glass clamp plate 1, installs LED lamp area 4 in the bottom surface of glass clamp plate 1, can supply light for the internal space of outer cauldron in the experimentation, is convenient for observe.
In the embodiment of the present invention, as shown in fig. 6, the sample holder 10 includes a circular bottom plate 101 and a sample stage 104 installed at the center of the circular bottom plate 101, and a plurality of rectangular grooves 102 are symmetrically formed in the outer periphery of the circular bottom plate 101 along the radial direction.
In the embodiment of the invention, a guide hole 103 is formed on the circular base plate 101, the circular base plate 101 and the base plate 12 are coaxially arranged and are connected in a guiding manner through a guide shaft 11, the top end of the guide shaft 11 is installed on the base plate seat, 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 a circular base plate 101 of the sample holder 10; the surface of the sample table 104 is flat, a plurality of sample injection holes 81 with the diameter less than 2mm are formed in the direction vertical to the upper surface, and each sample injection hole 81 can be independently opened or closed through a connector or a plug below; 4 rectangular grooves 102 which are symmetrically distributed are formed in the outer edge of the circular chassis 101, so that the mutual interference between the movement of the sample holder 10 along the Z direction and the movement of the piston of the hydraulic cylinder piston rod in the X and Y directions in the loading and unloading processes is avoided; the base circular table 1 is provided with a mounting hole 1 for mounting a guide shaft 11, and the circular chassis 101 is further provided with a plurality of centrosymmetric circular guide holes 103 which are matched with the guide shaft 11 fixed on the base plate seat to ensure that the sample seat 10 does not deflect in the process of moving along the Z direction.
In the embodiment of the invention, as shown in fig. 2 and 3, the microscopic visual rock hydraulic fracturing indoor simulation device further comprises a glass plug 5, two ends of the glass plug 5 are respectively abutted to 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 the outer side wall of the sample 8 is hermetically sleeved with a sealing rubber sleeve. The glass plug 5 is a cubic 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 5 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-sectional dimension of the glass plug 5 is consistent with that of the experimental sample 8.
Transparent sealing pieces are arranged between the sample 8 and the sample table 104 in a sealing mode, and the shape and the size of the sample 8, the transparent sealing pieces and the sample table 104 are consistent.
In the embodiment of the present invention, as shown in fig. 5, the present invention further includes a staggered loading plate group 9 installed on the sample holder 10, the staggered loading plate group 9 is a rectangular frame structure formed by enclosing four staggered loading plates 91, and the inner side of the staggered loading plate group 9 is tightly sealed with the outer side wall of the sealing rubber sleeve. The dislocation loading plate 91 is an L-shaped metal part, the short end of the dislocation loading plate 91 is provided with a limit pin hole 92, the long end of the dislocation loading plate 91 is provided with a limit groove 93,4 dislocation loading plates 91 are respectively placed on 4 edges of the experimental sample 8, the experimental sample 8 is limited through the cooperation of pins, the limit pin holes 92 and the limit grooves 93, and the phenomena of dislocation and uneven stress of the experimental sample 8 in the loading process are avoided.
Furthermore, a glass pressing plate 1, an experimental sample 8 and a sample seat 10 are sequentially arranged in the cylindrical hollow space of the outer kettle body from top to bottom, transparent sealing sheets for sealing are arranged between the experimental sample 8 and the glass pressing plate 1 as well as between the experimental sample 8 and the sample seat 10, and the visibility is ensured while the upper surface and the lower surface of the experimental sample 8 are sealed; a sealing rubber sleeve is placed 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 externally mounted of sealing rubber sleeve has dislocation load board 91, and with the cooperation of the pneumatic cylinder piston rod of X, Y direction for experiment sample 8 applys even load, compresses tightly sealing rubber sleeve when applying load, realizes the complete sealing in experiment sample 8 place space.
In addition, the bottom of the bottom plate seat is provided with a supporting frame 50 with a hollow structure, so that the lower component can be conveniently operated, and the height of the supporting frame is greater than that of the vertical confining pressure hydraulic cylinder.
In the embodiment of the invention, the confining pressure pump group 30 is further included 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 along the X direction and the Y direction in the same plane and abut against the outer side wall of the dislocation loading plate 91, and the piston rod of the vertical confining pressure hydraulic cylinder 13 penetrates through the base plate 12 along the Z direction and abuts against the sample holder 10. The confining pressure pump group 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 and Y directions and 1 hydraulic cylinder in the Z direction through pipelines, and the fluid injection pump 40 is connected with a joint of a liquid injection hole 105 at the bottom of the sample seat 10 through a pipeline.
When the microscopic visualization rock hydraulic fracturing indoor simulation device is used for carrying out simulation experiments, the following examples are used for more clearly understanding the operation steps of the simulation device.
Interaction experimental process of hydraulic fracture and natural fracture and cave
The method comprises the following steps: 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 holder 10 through a pipeline, and the bottoms of the other liquid injection holes 105 are sealed by screw plugs;
step two: placing the transparent sealing sheet on a rectangular sample table 104 of the sample holder 10, and wetting, wherein an opening is formed at a position corresponding to a liquid injection hole 105 of the sample table 104;
step three: placing a prepared experimental sample with interaction between the hydraulic fracture and the natural fracture hole on a transparent sealing sheet, wherein the sizes of the sample, the transparent sealing sheet and the sample table 104 are kept consistent, and the opening positions of the sample, the transparent sealing sheet and the sample table 104 are in one-to-one correspondence, so that the smoothness of a fluid channel is guaranteed;
step four: placing a transparent sealing sheet for sealing the upper surface of an experimental sample above the sample and wetting the transparent sealing sheet, and sleeving a rubber sealing sleeve on the outer sides of the sample and the sample table 104 from top to bottom to finish the assembly of a sealing element;
step five: sleeving the staggered loading plate 91 on the outer side of the rubber sealing sleeve to enable the corners of the inner side of the staggered loading plate to be aligned with the corners of the outer side of the rubber sealing sleeve respectively;
step six: selecting a glass plug 5 with the same size and the proper height as the experimental sample, placing the glass plug 5 above the sample, and ensuring that more than 10mm below the glass plug 5 is embedded into the rubber sealing sleeve;
step seven: installing a top cover 2 and a glass pressing plate 1 embedded with window glass 3, fastening and connecting the glass pressing plate with bolts, installing a high-speed camera bracket and a high-speed camera through redundant screw holes in the glass pressing plate 1, enabling the camera of the high-speed camera to be opposite to the window glass 3, and opening an LED lamp belt 4 to supplement a light source;
step eight: opening the lateral confining pressure hydraulic cylinder 6 and the vertical confining pressure hydraulic cylinder 13, applying three-way confining pressure to the experimental sample, keeping the three-way confining pressure balanced loading as much as possible, and avoiding stress concentration in the experimental sample before the experiment;
simultaneous injection
Step nine: all joints of all liquid injection holes 105 at the bottom of the sample holder 10 are communicated, the fluid injection pump 40 is started, the pre-prepared experimental fluid is injected, and simultaneously, the high-speed camera is turned on to completely record the experimental process;
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 dismounted from the upper part of the experiment frame at one time after the unloading, and the glass plug 5, the staggered loading plate 91, the sealing piece and the pressed experiment sample are sequentially taken out;
step eleven: placing the pressed experimental sample under a microscope, observing crack forms, crack tip forms and the like, and performing post-treatment analysis;
step twelve: analyzing the dynamic expansion characteristics of the crack quantitatively by pixel analysis of a high-definition bitmap, 1) researching the path and the crack width change in the dynamic expansion process of the crack; 2) And (4) combining the tracer added into the fluid to research the flow characteristics of the fluid in the dynamic expansion process of the fracture.
Sequentially filling liquid
Step nine: switching on a first liquid injection hole 105 at the bottom of the sample holder 10 according to the experimental scheme, starting the fluid injection pump 40, injecting the pre-prepared experimental fluid, and simultaneously turning on the high-speed camera to completely record the experimental process;
step ten: after the hydraulic fracture penetrates the test sample, the fluid injection pump 40 is closed, and the next injection hole 105 at the bottom of the sample holder 10 is connected according to the experimental scheme, so that the experiment is carried out.
Step eleven: repeating the step ten, after all the liquid injection holes 105 are sequentially communicated and the experiment is completed, closing the injection pump set, operating the lateral confining pressure hydraulic cylinder 6 and the vertical confining pressure hydraulic cylinder 13 for unloading, 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 staggered loading plate 91, the sealing element and the pressed experimental sample;
step twelve: placing the pressed experimental sample under a microscope, observing crack forms, crack tip forms and the like, and performing post-treatment analysis;
step thirteen: analyzing pixels of a high-definition bitmap, 1) researching the path and the seam width change in the dynamic crack expansion process, and quantitatively analyzing dynamic crack expansion characteristics; 2) And (4) combining the tracer added into the fluid to research the flow characteristics of the fluid in the dynamic expansion process of the fracture.
In the description of the present invention, it is to 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 relative importance or to imply that the number of technical features indicated are in fact significant. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.
In the present invention, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as being permanently connected, detachably connected, or integral; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like 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 invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer 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, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A microscopic visualization rock plate hydraulic fracturing indoor simulation method is characterized by comprising the following steps:
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 complex working conditions of hydraulic crack expansion;
presetting a plurality of natural fractures with different forms on the experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture body;
presetting a plurality of natural fracture holes with different forms on the experimental sample, and simulating the initiation and the expansion of hydraulic fractures in a fracture hole body;
and filling a temporary plugging agent at the tip of the preset crack, and simulating the working condition of temporary plugging steering fracturing.
2. The microscopic visualization rock plate hydraulic fracturing indoor simulation method of claim 1, wherein the step of designing the parameters of the liquid injection hole and the preset fracture and simulating the complex working condition of hydraulic fracture propagation comprises the following steps:
when the number of the preset cracks is one, acquiring morphological parameters of the hydraulic cracks;
comparing fracture initiation and expansion images of the hydraulic fracture under different preset fracture forms in a plurality of experimental samples;
and evaluating the influence of morphological parameters, three-way stress relation and injection flow of the preset fracture on the initiation and expansion of the fracture according to the comparison result.
3. The microscopic visualization rock plate hydraulic fracturing indoor simulation method according to claim 1, wherein the step of designing the parameters of the liquid injection hole and the preset fracture and simulating the complex working condition of hydraulic fracture propagation comprises the following steps:
when the number of the preset cracks is multiple, controlling the liquid injection sequence of a plurality of liquid injection holes in the experimental sample so as to simulate the complex working conditions of initiation and expansion of the close cut fracture group;
and (3) designing morphological parameters of a plurality of preset fractures in the experimental sample, and acquiring the expansion morphology of the fracture group and the mutual interference rule among a plurality of hydraulic fractures under the close cutting and fracturing working condition.
4. The microscopic visualization rock plate hydraulic fracturing indoor simulation method of claim 1, wherein the step of presetting a plurality of natural fractures with different morphologies on the experimental sample and simulating the initiation and propagation of hydraulic fractures in a fracture body comprises:
designing an interactive relation between a preset fracture and a natural fracture according to actual working conditions in a reservoir;
when the natural fracture and the predicted expansion path of the hydraulic fracture do not intersect, acquiring the influence rule of a stress field under the influence of the natural fracture on the expansion of the hydraulic fracture;
and acquiring an interaction rule between the natural fracture and the hydraulic fracture when the natural fracture and the predicted propagation path of the hydraulic fracture intersect.
5. The indoor simulation method for microscopic visualization rock plate hydraulic fracturing, as claimed in claim 1, wherein the step of presetting a plurality of natural fracture holes with different shapes on the experimental sample and simulating the initiation and propagation of hydraulic fracture in the fracture hole body comprises:
designing an interactive relation between a preset fracture and a natural fracture hole according to actual working conditions in a reservoir;
when the natural fracture-cave does not intersect with the predicted expansion path of the hydraulic fracture, acquiring the influence rule of a stress field under the influence of the natural fracture-cave on the expansion of the hydraulic fracture;
and when the natural fracture-cave intersects with the predicted propagation path of the hydraulic fracture, acquiring an interaction rule between the natural fracture-cave and the hydraulic fracture.
6. The microscopic visualization rock plate hydraulic fracturing indoor simulation method of claim 1, wherein the step of filling a temporary plugging agent at the tip of the pre-set fracture and simulating a temporary plugging diversion fracturing condition comprises:
designing morphological parameters of the temporary plugging agent in the seam according to the actual working conditions and the temporary plugging process in the reservoir;
filling temporary plugging agents of corresponding types and forms at the tips of the preset cracks according to the form parameters of the temporary plugging agents;
and obtaining the turning and expanding rule of the hydraulic fracture under the corresponding temporary plugging process after the experiment.
7. A microscopic visualization rock plate hydraulic fracturing indoor simulation device, which is used for the microscopic visualization rock plate hydraulic fracturing indoor simulation method according to any one of claims 1 to 6, and comprises the following components:
the reaction kettle comprises an outer kettle body, wherein a closed cylindrical space is formed inside the outer kettle body, the top of the outer kettle body is arranged in a transparent mode, a sample seat (10) used for placing a sample (8) is arranged in the cylindrical space, and a liquid injection hole (105) is formed in the bottom of the sample seat (10);
the image acquisition assembly is axially arranged above the outer kettle body and is used for acquiring a dynamic image of a sample (8) in the outer kettle body in the fracturing process;
the lateral confining pressure hydraulic cylinder (6) and the vertical confining pressure hydraulic cylinder (13) respectively apply loads to the sample (8) along the X direction, the Y direction and the Z direction in the same plane;
and a fluid injection pump (40) connected to the injection hole (105) through a pipe and used for injecting the sample (8) from the bottom.
8. The visual rock plate dynamic fracture experimental apparatus of claim 7, characterized in that, the outer kettle body includes an outer barrel (7), an upper top cover (2) and a base plate (12) installed at the top end and the bottom end of the outer barrel (7) and a glass pressing plate (1) installed on the upper top cover (2), a viewing window convenient for observing the inner part of the outer kettle body is opened at the center of the upper top cover (2), the glass pressing plate (1) is an annular plate-shaped structure, an installation groove for embedding the viewing window glass (3) is formed along the circumferential direction on the inner side wall of the glass pressing plate (1), and the viewing window is coaxially covered by the viewing window glass (3).
9. The apparatus for visualizing rock slab dynamic fracture experiment of claim 8, wherein the sample holder (10) comprises a circular bottom plate (101) and a sample stage (104) installed at the center of the circular bottom plate (101), a guide hole (103) is opened on the circular bottom plate (101), the circular bottom plate (101) and the base plate (12) are coaxially arranged and are connected in a guiding manner through a guide shaft (11), the bottom end of the guide shaft (11) is installed on the base plate holder, and the top end of the guide shaft (11) penetrates through and is locked in the guide hole (103).
10. The visual rock plate dynamic fracture experimental device according to claim 5, further comprising a glass plug (5) with two ends respectively abutted against the window glass (3) and the sample (8), and a dislocation loading plate group (9) installed on the sample holder (10), wherein the glass plug (5), the sample (8) and the sample stage (104) jointly form a rectangular cylinder, a sealing rubber sleeve is sleeved on the outer side wall of the sample in a sealing manner, the dislocation loading plate group (9) is a rectangular frame structure formed by enclosing four dislocation loading plates (91), and the inner side of the dislocation loading plate group (9) is tightly sealed and attached to the outer side wall of the sealing rubber sleeve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210399821.1A CN115370341B (en) | 2022-04-15 | 2022-04-15 | Microcosmic visual rock plate hydraulic fracturing indoor simulation method and device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210399821.1A CN115370341B (en) | 2022-04-15 | 2022-04-15 | Microcosmic visual rock plate hydraulic fracturing indoor simulation method and device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115370341A true CN115370341A (en) | 2022-11-22 |
| CN115370341B CN115370341B (en) | 2023-11-28 |
Family
ID=84060436
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210399821.1A Active CN115370341B (en) | 2022-04-15 | 2022-04-15 | Microcosmic visual rock plate hydraulic fracturing indoor simulation method and device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115370341B (en) |
Citations (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4830106A (en) * | 1987-12-29 | 1989-05-16 | Mobil Oil Corporation | Simultaneous hydraulic fracturing |
| US20130218545A1 (en) * | 2012-02-21 | 2013-08-22 | Robert J. Murphy | Methods and systems for subterranean bore hole fracture simulation |
| 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 |
| US20150204174A1 (en) * | 2012-08-24 | 2015-07-23 | Schlumberger Technology Corporation | System and method for performing stimulation operations |
| 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 |
| US20160363691A1 (en) * | 2015-06-15 | 2016-12-15 | Petrochina Company Limited | Physical simulation method and experiment device of fracture-cavity carbonate reservoir hydrocarbon charge |
| 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 | A kind of intrinsic fracture and man-made fracture Extending Law Logistics automatic system method |
| 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 |
| US20200386081A1 (en) * | 2019-06-05 | 2020-12-10 | Southwest Petroleum University | Optimized design method for temporary blocking agent to promote uniform expansion of fractures produced by fracturing in horizontal wells |
| 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 |
-
2022
- 2022-04-15 CN CN202210399821.1A patent/CN115370341B/en active Active
Patent Citations (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4830106A (en) * | 1987-12-29 | 1989-05-16 | Mobil Oil Corporation | Simultaneous hydraulic fracturing |
| US20130218545A1 (en) * | 2012-02-21 | 2013-08-22 | Robert J. Murphy | Methods and systems for subterranean bore hole fracture simulation |
| US20150204174A1 (en) * | 2012-08-24 | 2015-07-23 | Schlumberger Technology Corporation | System and method for performing stimulation operations |
| 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 |
| US20160363691A1 (en) * | 2015-06-15 | 2016-12-15 | Petrochina Company Limited | Physical simulation method and experiment device of fracture-cavity carbonate reservoir hydrocarbon charge |
| 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 | A kind of intrinsic fracture and man-made fracture Extending Law Logistics automatic system method |
| US20200386081A1 (en) * | 2019-06-05 | 2020-12-10 | Southwest Petroleum University | Optimized design method for temporary blocking agent to promote uniform expansion of fractures produced by fracturing in horizontal wells |
| 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 |
|---|
| 侯冰等: "页岩暂堵转向压裂水力裂缝扩展物模试验研究", 辽宁石油化工大学学报 * |
| 李新勇等: "缝洞型碳酸盐岩储层压裂效果评价方法试验研究", 石油钻探技术 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN115370341B (en) | 2023-11-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11313775B2 (en) | Device and method for evaluating fracture initiation and propagation, and stress sensitivity of propped fracture | |
| CN110987638A (en) | Visual true triaxial hydraulic fracture test device and method | |
| CN104963673B (en) | Simulate the visual experimental apparatus that fiber diversion agent temporarily blocks up hydraulic fracture | |
| CN108386177A (en) | The 3-dimensional multi-layered more well pressure break supporting cracks of one kind monitoring experimental system and method in real time | |
| WO2016141621A1 (en) | Integrated test system for true-triaxial flow pressure fracturing, slotting, leakage and gas expulsion | |
| CN208137925U (en) | A kind of 3-dimensional multi-layered more well pressure break supporting crack real-time monitoring experimental systems | |
| CN110924933A (en) | Visual experiment method for dynamically simulating shale fracturing fracture network | |
| CN110469311B (en) | Dynamic expansion coarse crack network visualization device under simulated confining pressure condition | |
| CN113153255B (en) | Shaft device and method for simulating horizontal well crack synchronous propagation experiment | |
| CN111119831A (en) | Indoor simulation test device for staged fracturing of horizontal well and operation method thereof | |
| CN105974084A (en) | In-coal-seam gas extraction experiment simulation device | |
| CN111366472B (en) | True triaxial hydraulic fracturing physical simulation equipment and method for variable core size | |
| CN205154123U (en) | Experimental device for simulation SAGD in -process hydraulic fracturing mechanism | |
| CN115370341A (en) | Microscopic visual rock plate hydraulic fracturing indoor simulation method and device | |
| CN116337639B (en) | Multilayer system three-dimensional well pattern fracturing simulation experiment device and method | |
| CN116357283A (en) | Three-dimensional fracturing competition liquid injection simulation system and method | |
| CN111734381A (en) | Natural crack-containing fracturing and seam-making device for simulating injection-production relation of multiple injection-production well pattern | |
| CN114993836A (en) | Visual rock plate dynamic fracture experimental device and monitoring method | |
| CN110821466B (en) | Visual fracturing technology research experimental apparatus with variable seam width | |
| CN208921549U (en) | Stress test rock core clamps simulator | |
| AlTammar et al. | Theoretical and Experimental Comparison Study of Weak Point Shape Effect on Openhole Fracturing Pressure | |
| CN114607331B (en) | Horizontal well sectional volume fracturing simulation test device and method | |
| Eshiet et al. | An overview of principles and designs of hydraulic fracturing experiments and an inquiry into the influence of rock permeability and strength on failure mode | |
| CN110821467B (en) | Pressure-resistant visual fracturing technology research experimental device | |
| CN216771345U (en) | Small-size hydraulic fracturing triaxial evaluation test pressure device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |