CN113532996B - Matrix-fracture fluid three-dimensional flow model and preparation method and application thereof - Google Patents
Matrix-fracture fluid three-dimensional flow model and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to the technical field of conventional and unconventional oil and gas resource oil displacement and reservoir transformation of fractured oil and gas reservoirs, compact oil and gas, shale oil and gas and the like, and discloses a matrix-fractured fluid three-dimensional flow model and a preparation method and application thereof. The model is made of a rock core with the length of L, the model comprises n cracks and m grooves which are distributed in a staggered mode in the axial direction and the radial direction, the cracks and the grooves are respectively located at two ends of the model, and n and m are integers which are not less than 1; the length of the crack is equal to that of the groove, the length of the crack is a, the shortest distance from each groove to each crack is h, and h is L-a and is larger than 0. The model can meet the condition that the pressure gradients of most matrixes in the slotted net rock core are equal, so that axial flow and radial flow exist in the model simultaneously, and three-dimensional flow in the model is realized.
Description
Technical Field
The invention relates to the technical field of conventional and unconventional oil and gas resource oil displacement and reservoir transformation of fractured oil and gas reservoirs, compact oil and gas, shale oil and gas and the like, in particular to a matrix-fractured fluid three-dimensional flow model and a preparation method and application thereof.
Background
The mining difficulty of conventional oil gas resources is relatively small, but the resource amount of the conventional oil gas resources only accounts for 20% of the total amount of global resources, and unconventional oil gas resources such as compact oil, compact gas, shale oil and shale gas account for 80% of the total amount of the resources. In recent years, the difficulty of stable production of conventional oil and gas resources in China is gradually increased, and the repeated exploration of reserves is simultaneously improved along with the new increase of unconventional oil and gas resources, so that the later is gradually the development key point. However, unconventional oil and gas resources represented by shale oil and gas resources are generally poor in physical properties and require reservoir reconstruction. Hydraulic fracturing is a common and effective means of reservoir reformation for tight reservoirs. Aiming at a reservoir with poor physical properties, a large amount of fluid is injected into the reservoir after drilling, and an artificial fracture is formed in a target reservoir, so that a seepage channel is enlarged, and the oil and gas yield can be effectively improved. In a real stratum, a fracture formed through hydraulic fracturing forms a branch seam at a stress mutation position, and the fracture extending direction also has transient property (the stratum hydraulic fracturing fracture and a simple seam and a complex seam are schematically shown in figure 1). Meanwhile, the cracks have certain properties such as space crosslinking property and the like.
In order to research the oil-gas seepage rule of a compact reservoir, the traditional method generally adopts a small-size natural fracture core or artificial fracture core to perform related research. However, the above research methods have certain problems. Firstly, the self characteristics of a natural fracture core cannot be controlled, and particularly, the inversion of the whole reservoir is inevitable to be complete by carrying out experiments on small-size natural fractures; secondly, no matter natural fracture or artificial fracture is used at present, the whole simple fracture penetrates through a core model, and the utilization degree of the core matrix is obviously insufficient when fluid flows through the fracture. Even though the multidirectional multilayer full-diameter fracture core seepage simulation device and the application thereof are disclosed in the Chinese patent CN112816389 (application No. 202011643748.5), the adopted full-diameter core has great randomness, the experimental result changes along with the sample property, and experimental instruments such as nuclear magnetism and the like are difficult to utilize due to the size requirement of the sample. Therefore, the method for researching the seepage rule of the fracture core is not beneficial to accurately evaluating the fracturing modification effect.
Disclosure of Invention
The invention aims to solve the problems that the fracture rock core in the prior art is a whole simple fracture penetrating rock core model, the use degree of fluid to rock core matrix is obviously insufficient when the fluid flows through the fracture, the full-diameter fracture rock core is random, the experimental result changes along with the sample property, the full-diameter fracture rock core has large size, experimental instruments such as nuclear magnetism are difficult to use and the like, and provides a matrix-fracture fluid three-dimensional flow model, a preparation method and application thereof. In the invention, through the design of the shape and the size of the model, the characteristic that the pressure gradient of most matrixes in the slotted net rock core is equal is met, so that axial flow and radial flow exist in the model simultaneously, the three-dimensional flow in the model is realized, the problems of insufficient matrix utilization and high randomness of experimental conditions in the traditional method are solved, and meanwhile, the slotted net rock core fracture simulation model can be combined with various experimental instruments, has a wide application range and is beneficial to accurately evaluating the fracture transformation effect.
The invention provides a matrix-fracture fluid three-dimensional flow model, which is manufactured by a rock core with the length of L, wherein the model comprises n fractures and m grooves which are distributed in a staggered manner along the axial direction and the radial direction, the fractures and the grooves are respectively positioned at two ends of the model, and n and m are integers which are not less than 1; the length of the crack is equal to that of the groove, the length of the crack is a, the shortest distance from each groove to each crack is h, and h is L-a and is larger than 0.
Preferably, the core is a cylinder or a cube, preferably a cylinder.
Preferably, the core is sandstone, shale or carbonate.
Preferably, m is 2 n.
Preferably, the length L of the core is 30-1000 mm.
Preferably, the length a of the slits and the grooves is 20 to 990 mm.
Preferably, the width b of the slit is 0.5-3 mm.
Preferably, the width c of the groove is 1-5 mm.
In a second aspect, the present invention provides a method for making the three-dimensional matrix-fracture fluid flow model, which comprises the following steps:
(1) selecting a rock core with a proper shape, size and lithology as a model making material according to actual needs;
(2) cutting n cracks with the length of a and the width of b at one end of a core with the length of L and the width or the diameter of d, wherein a is less than L, n is an integer more than or equal to 1,
preferably, equally cutting n cracks with the length of a and the width of b on the end face;
(3) m grooves with the length of a, the width of c and the depth of e are manufactured at the other end of the core, the shortest distance from each groove to each crack is h, h is L-a and h is more than 0,
preferably, m grooves with the length of a, the width of c and the depth of e are manufactured along the direction perpendicular to the crack and passing through the center of the end face; or
M grooves with the length of a, the width of c and the depth of e are manufactured along the direction of the angular bisector of two adjacent cracks.
Preferably, the length L of the core is 30-1000mm, and the width or diameter d of the core is 30-1000 mm.
Preferably, the length a of the slit and the groove is 20-990mm, and the width b of the slit is 0.5-3 mm.
Preferably, the width c of the groove is 1-5mm, and the depth e of the groove is 1-5 mm.
Preferably, m is 2 n.
In a third aspect, the invention provides an application of the matrix-fracture fluid three-dimensional flow model manufactured by the method in researching the reservoir seepage law of the fractured hydrocarbon reservoir, and the application comprises simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir by using the matrix-fracture fluid three-dimensional flow model and an experimental instrument.
Preferably, the fluid flow comprises continuous and discontinuous co-directional fluid flow, non-co-directional fluid flow and transient plugging and flow regulation of the three-dimensional flow model of the heterogeneous fluid to the matrix-fracture fluid; the continuous co-current fluid flow modes comprise water flooding, polymer flooding, surfactant flooding, heat injection and microbial flooding; the discontinuous cocurrent fluid flow mode comprises water-gas alternate injection and/or slug injection; the non-co-directional fluid flow modes include forward fluid loss, blind well fluid exchange, and reverse flowback; the heterogeneous fluid includes a flow modifier carrying solid particles, a flow modifier carrying soft elastomeric particles, and a fluid carrying a transient blocking agent.
Preferably, the method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir comprises the following steps:
m1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
m2, carrying out leak-proof treatment on the cracks and grooves in the model by filling proppant;
m3, carrying out saturated oil treatment on the model;
m4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
m5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before displacement;
m6, carrying out a displacement experiment by using heavy water at one end of the model for fracture making, and simultaneously carrying out real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of continuous cocurrent fluid flow in a reservoir of the fractured oil and gas reservoir.
Preferably, the method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir comprises the following steps:
s1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
s2, filling propping agents into the cracks and the grooves in the model to perform leak-proof treatment;
s3, placing the model into a holder, and applying confining pressure to simulate the formation pressure;
s4, fluid loss process: performing a fluid loss experiment at one end of the model fracture, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of forward fluid loss in a reservoir of the fractured oil and gas reservoir;
s5, well closing process: closing valves at two ends of the rock core holder after the filtration is finished to realize pressurized blank well, and simultaneously carrying out real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of blank well fluid exchange in a reservoir of the fractured oil-gas reservoir;
s6, a flow-back process: and performing a flowback experiment at one end of the model groove, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of reverse flowback in a fractured reservoir.
Preferably, the method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir comprises the following steps:
p1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
p2, carrying out leak-proof treatment on the cracks and grooves in the model by filling proppant;
p3, carrying out saturated oil treatment on the model;
p4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
p5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before flow regulation displacement;
p6, performing a displacement experiment by using heavy water at one end of the model for crack formation, injecting a proper amount of plugging agent to plug part of cracks after a period of time, then continuing to perform the displacement experiment by using the heavy water, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of temporary plugging and flow regulation of heterogeneous fluid in a fractured oil and gas reservoir.
Compared with the fracture core in the prior art, the core model designed and manufactured by the invention has the following advantages:
1. in the prior art, the fracture core is a whole simple fracture penetrating core model, and the use degree of a core matrix is obviously insufficient when fluid flows through the fracture; the invention respectively manufactures n cracks and m grooves with the same length at two ends of the core, simultaneously the cracks and the grooves do not penetrate through the core model, and the shortest distance from the grooves to the cracks is equal to the difference between the length of the core and the length of the cracks (or the grooves).
2. The self characteristics of the natural fracture core are uncontrollable, the whole reservoir is easy to invert by experiments, the self characteristics of the full-diameter core have great randomness, and the experiment result changes along with the properties of a sample; the method for manufacturing the fractured core can be used for selectively manufacturing the core with simple fractures or complex fractures according to actual needs by using the core with proper shape, size and lithology as a material according to the actual needs, so that the problem of high randomness of experimental conditions is solved.
3. The model manufactured according to the method can select the rock core with proper size as the material according to the actual requirement, the manufactured model is not limited by the size, can be combined with various experimental instruments, has wide application range, can accurately simulate and evaluate the fluid flow law of the reservoir of the fractured oil and gas reservoir from multiple aspects, and is favorable for accurately evaluating the fracturing modification effect. Particularly, the model is put into a low-field nuclear magnetic resonance analyzer, and the pore structure characteristics and the fluid distribution characteristics of the rock core can be measured by distinguishing signals.
4. The model manufactured by the invention has the cracks and the grooves simultaneously, so that the fluid can not only act on the end face of the matrix, but also can enter the rock core through the grooves to act on the whole, and simultaneously, various processes (such as filtration, well plugging and flowback) in the stratum are simulated, and the simulation process is more sufficient and real.
5. By combining the model provided by the manufacturing method with an experimental method, the simulated fluid flow is more suitable for the actual situation of the reservoir, and the method has a more real performance evaluation reference value for researching the fluid seepage rule of the fractured oil and gas reservoir.
Drawings
FIG. 1 is a schematic view of a real formation hydraulic fracture and simple and complex fractures;
FIG. 2 is a schematic view of a simple slit model made in example 1;
FIG. 3 is a schematic view of a complex slit model made in example 2;
FIG. 4 is a schematic diagram of a simple slot model fracturing fluid loss process in an application example;
FIG. 5 is a schematic diagram of a simple fracture model fracturing fluid well-closing process in an application example;
FIG. 6 is a schematic diagram of a simple slot model fracturing fluid flowback process in an application example;
FIG. 7 is a spectrum of T2 before and after application displacement in an application example;
FIG. 8 is a graph of the fluid loss process T2 in an application example;
FIG. 9 is a diagram of a stuffer well process T2 in an application example;
FIG. 10 is a diagram of a flow-back process T2 in an application example;
fig. 11 is a spectrum of T2 before and after application flow regulation in the application example.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The matrix-fracture fluid three-dimensional flow model is manufactured by a rock core with the length of L, the model comprises n fractures and m grooves which are distributed in a staggered mode along the axial direction and the radial direction, the fractures and the grooves are respectively located at two ends of the model, n and m are integers which are not less than 1, the lengths of the fractures and the grooves are equal to a, the shortest distance from each groove to each fracture is h, and h is L-a and is more than 0.
The rock core model provided by the invention has specific structure and size characteristics, and can ensure that the pressure gradients of most matrixes in the slotted net rock core are equal, so that axial flow and radial flow can simultaneously exist in the fluid in the model, and further, the three-dimensional flow in the model is realized.
In the invention, the rock core with proper shape and lithology can be selected as the material for making the model according to actual needs. In a particular embodiment, the core may be a cylinder or a cube, preferably a cylinder. In particular embodiments, the core may be sandstone, shale, or carbonate rock.
In the core model according to the present invention, there is no particular limitation between the number of cracks n and the number of recesses m. In a preferred embodiment, m is 2 n.
In the present invention, the size of the core is not particularly limited, and may be selected according to experimental needs or instrument size.
In a preferred embodiment, the core may have a length L of 30-1000mm, such as 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm and any value in the range of any two of these point values. In the invention, the core length L is controlled within the range, so that the detection result of a detection instrument (such as a nuclear magnetic resonance device, the optimal detection range of which is within 60mm of the center of the instrument) can be more accurate.
In a preferred embodiment, the length a of the slits and grooves may be 20-990mm, for example, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 990, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm and any value within a range defined by any two of these point values.
In a preferred embodiment, the width b of the slit may be 0.5-3mm, such as 0.5mm, 0.8mm, 1mm, 1.5mm, 2mm, 2.5mm or 3mm and any value in the range of any two of these point values.
In a preferred embodiment, the width c of the groove may be 1-5mm, e.g. 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm and any value in the range of any two of these point values.
The invention provides a method for manufacturing a matrix-fracture fluid three-dimensional flow model, which comprises the following steps of:
(1) selecting a rock core with a proper shape, size and lithology as a model making material according to actual needs;
(2) cutting n cracks with the length of a and the width of b at one end of a core with the length of L and the width or the diameter of d, wherein a is less than L, n is an integer more than or equal to 1,
preferably, equally cutting n cracks with the length of a and the width of b on the end face;
(3) m grooves with the length of a, the width of c and the depth of e are manufactured at the other end of the core, the shortest distance from each groove to each crack is h, h is L-a and h is more than 0,
preferably, m grooves with the length of a, the width of c and the depth of e are manufactured along the direction perpendicular to the crack and passing through the center of the end face; or
M grooves with the length of a, the width of c and the depth of e are manufactured along the direction of the angular bisector of two adjacent cracks.
The method is simple to operate, and models with different structures and sizes can be manufactured according to actual requirements. In the invention, n can be any integer with the value of more than or equal to 1. When n is 1, the manufactured model is a simple seam model; when the gap is larger than or equal to 2, the manufactured model is a complex gap model.
In the method according to the invention, the core may have a length L of 30-1000mm, for example 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm and any value in the range formed by any two of these point values.
In the method according to the invention, the core may have a width or diameter d of 30-500mm, for example 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 200m, 300mm, 400mm, 500mm and any value in the range of any two of these values.
In the method according to the invention, the length a of the slits and grooves may be 20-990mm, for example 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 990, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm and any value in the range formed by any two of these point values.
In the method according to the invention, the width b of the slit may be 0.5-3mm, for example 0.5mm, 0.8mm, 1mm, 1.5mm, 2mm, 2.5mm or 3mm and any value in the range of any two of these point values.
In the method according to the invention, the width c of the groove may be 1-5mm, for example 1mm, 2mm, 3mm, 4mm, 5mm and any value in the range of any two of these point values. The depth e of the groove may be 1-5mm, e.g. 1mm, 2mm, 3mm, 4mm, 5mm and any value in the range of any two of these point values.
In the method of the invention, the number n of cracks and the number m of grooves are not particularly limited as long as a core model with the pressure gradient of most matrixes in the slotted net core equal to each other can be prepared. In a preferred embodiment, m is 2 n.
The invention also provides application of the matrix-fracture fluid three-dimensional flow model manufactured by the method in researching the reservoir seepage rule of the fractured oil and gas reservoir. The application comprises the steps of simulating and evaluating the reservoir fluid flow rule of the fractured oil and gas reservoir by adopting the matrix-fractured fluid three-dimensional flow model and an experimental instrument.
In a specific application process, the fluid flow comprises continuous and discontinuous cocurrent fluid flow, non-cocurrent fluid flow and temporary plugging and flow regulation of a three-dimensional flow model of the heterogeneous fluid to the matrix-fracture fluid.
In more specific applications, the continuous co-current fluid flow regime includes water flooding, polymer flooding, surfactant flooding, heat injection, and microbial flooding; the discontinuous cocurrent fluid flow mode comprises water-gas alternate injection and/or slug injection; the non-co-directional fluid flow modes include forward fluid loss, blind well fluid exchange, and reverse flowback; the heterogeneous fluid includes a flow modifier carrying solid particles, a flow modifier carrying soft elastomeric particles, and a fluid carrying a transient blocking agent.
In a specific application process, the method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir by using an indoor displacement physical simulation experiment and combining the nuclear magnetic resonance instrument comprises the following steps:
m1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
m2, carrying out leak-proof treatment on the cracks and grooves in the model by filling proppant;
m3, carrying out saturated oil treatment on the model;
m4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
m5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before displacement;
m6, carrying out a displacement experiment by using heavy water at one end of the model for fracture making, and simultaneously carrying out real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of continuous cocurrent fluid flow in a reservoir of the fractured oil and gas reservoir.
In the second specific application process, the method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir is illustrated by an indoor fluid loss-blank well-flowback physical simulation experiment and the use of a nuclear magnetic resonance instrument. The method comprises the following steps:
s1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
s2, filling propping agents into the cracks and the grooves in the model to perform leak-proof treatment;
s3, placing the model into a holder, and applying confining pressure to simulate the formation pressure;
s4, fluid loss process: performing a fluid loss experiment at one end of the model fracture, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of forward fluid loss in a reservoir of the fractured oil and gas reservoir;
s5, well closing process: closing valves at two ends of the rock core holder after the filtration is finished to realize pressurized blank well, and simultaneously carrying out real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of blank well fluid exchange in a reservoir of the fractured oil-gas reservoir;
s6, a flow-back process: and performing a flowback experiment at one end of the model groove, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of reverse flowback in a fractured reservoir.
In a third specific application process, the method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir by using an indoor flow-regulating displacement physical simulation experiment and combining the use of a nuclear magnetic resonance instrument comprises the following steps:
p1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
p2, carrying out leak-proof treatment on the cracks and grooves in the model by filling proppant;
p3, carrying out saturated oil treatment on the model;
p4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
p5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before flow regulation displacement;
p6, performing a displacement experiment by using heavy water at one end of the model for crack formation, injecting a proper amount of plugging agent to plug part of cracks after a period of time, then continuing to perform the displacement experiment by using the heavy water, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of temporary plugging and flow regulation of heterogeneous fluid in a fractured oil and gas reservoir.
The present invention will be described in detail by way of examples, but the scope of the present invention is not limited thereto.
EXAMPLE 1 production of simple slit model
(1) Selecting a cylindrical sandstone core with the length of 30mm and the diameter of 25mm as a model making material;
(2) according to the experimental requirement, 1 crack is cut at one end of the core with the end surface equally divided, the length of the crack is 20mm, and the width of the crack is 1 mm;
(3) and 2 grooves are formed in the other end of the core along the direction perpendicular to the crack and passing through the center of the end face, the length of each groove is 20mm, the width of each groove is 2mm, the depth of each groove is 2mm, and the shortest distance from each groove to the crack is 10 mm.
Fig. 2 is a schematic view of a simple slit model made in example 1.
EXAMPLE 2 Complex seam model fabrication
(1) Selecting a cylindrical shale core with the length of 30mm and the diameter of 25mm as a model making material;
(2) according to the experimental requirement, 2 cracks are evenly cut on the end face of one end of the core, the length of each crack is 23.08mm, and the width of each crack is 1 mm;
(3) and 4 grooves are formed in the other end of the core along the directions of two adjacent fracture angle bisectors, the length of each groove is 23.08mm, the width of each groove is 2mm, the depth of each groove is 2mm, and the shortest distance from each groove to each fracture is 6.92 mm.
Fig. 3 is a schematic view of a complex slit model fabricated in example 2.
Application example (1)
The method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir is illustrated by an indoor displacement physical simulation experiment and the use of a nuclear magnetic resonance instrument by adopting the simple fracture model manufactured in the embodiment 1. The method comprises the following steps:
m1, cleaning and drying the simple seam model manufactured in the embodiment 1, and then selecting the proppant particles used on site to fill the cracks and the grooves in the model;
m2, filling propping agents into the cracks and the grooves in the model by using a metal gauze to perform leak-proof treatment;
m3, carrying out saturated oil treatment on the sand-filled model;
m4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
m5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before displacement;
m6, performing a displacement experiment by using heavy water at one end of the model seam making, and simultaneously performing a real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument (a T2 spectrum in the displacement process is shown in figure 7);
as can be seen from fig. 7, the abscissa of the graph is the relaxation time, the ordinate is the signal amplitude, the curve represents the T2 spectrum of the fracture model, the solid line represents the T2 spectrum before the experiment, and the dotted line represents the T2 spectrum after the experiment. The relaxation time at the intersection of the solid line and the abscissa in the graph is taken as the boundary point of the matrix and the fracture, namely the signal of the oil in the matrix is shown on the left side of the intersection of the solid line and the abscissa, and the signal of the oil in the fracture is shown on the right side. It can be seen that by fully saturating the oil, the matrix and the fracture in the model are both signaled to have oil, and as the displacement proceeds from the fracture end, the oil in the fracture is effectively displaced, while due to the presence of the grooves, the majority of the matrix is in a state of equal pressure gradient, and the oil in the matrix can also be effectively used.
Application example (2)
The method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir is illustrated by an indoor fluid loss-blind well-flowback physical simulation experiment and the use of a nuclear magnetic resonance instrument by adopting the simple fracture model manufactured in the example 1. The method comprises the following steps:
s1, cleaning and drying the simple seam model manufactured in the embodiment 1, and then selecting the proppant particles used on site to fill the cracks and the grooves in the model;
s2, filling propping agents into the cracks and the grooves in the model by using a metal gauze to perform leak-proof treatment;
s3, placing the sand-filled model into a holder, and applying confining pressure to simulate formation pressure;
s4, fluid loss process: performing a fluid loss experiment at one end of the model fracture, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of forward fluid loss in a reservoir of the fractured reservoir (a schematic diagram of a simple fracture model fracturing fluid loss process is shown in figure 4, and a T2 spectrogram of the fluid loss process is shown in figure 8);
s5, well closing process: closing valves at two ends of the core holder after the filtration is finished to realize pressurized blank well, and simultaneously carrying out real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of blank well fluid exchange in a reservoir of the fractured oil and gas reservoir (a schematic diagram of a simple fracture model fracturing fluid blank well process is shown in figure 5, and a T2 spectrogram of the blank well process is shown in figure 9);
s6, a flow-back process: and performing a flowback experiment at one end of the model groove, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of reverse flowback in a reservoir of the fractured reservoir (a schematic diagram of a simple fracture model fracturing fluid flowback process is shown in figure 6, and a T2 spectrogram of the flowback process is shown in figure 10).
As can be seen from fig. 4, in step S4, due to the existence of the groove, the remaining length of the core during core fracture formation is kept consistent with the shortest distance between the fracture and the groove, that is, the pressure gradient of the matrix part inside the core is basically consistent, so that most of the matrix in the fracture core can be fully utilized in the core fluid loss experiment to realize three-dimensional flow, and the real condition of fluid loss in the formation can be fully simulated. As can be seen from fig. 5, in step S5, after the fluid loss test is completed, because the pressure difference still exists between the two ends of the model and the capillary tube acting force exists in the matrix, the fluid still flows in the model, and the matrix is communicated with the fracture. As can be seen from fig. 6, in step S6, due to the existence of the groove, the flow-back fluid can not only act on the matrix end face, but also fully flow-back and pressurize the whole body by the groove penetrating into the core, so as to fully simulate the real flow-back situation in the formation.
As can be seen from fig. 8 to 10, the abscissa of the graph is the relaxation time, the ordinate is the signal amplitude, the curve represents the T2 spectrum of the fracture model, the dotted line represents the T2 spectrum before the experiment, and the solid line represents the T2 spectrum after the experiment. And taking relaxation time at the intersection of the curve and the abscissa in the graph as a boundary point of the matrix and the fracture, namely taking a fracturing fluid signal in the matrix on the left side of the intersection of the curve and the abscissa and taking a fracturing fluid signal in the fracture on the right side. FIG. 8 is a graph of the signals in the model after fluid loss from the model, and it can be seen that the signals in the matrix and in the fracture are both increased relative to the initial 0 level value; before the blind well, the dashed line in fig. 9, after the blind well, the signal in the fracture decreases and the signal in the matrix increases again, as can be seen by the presence of capillary forces and the presence of a certain flow of fracturing fluid in the fracture; before the dotted line in fig. 10 is flowback and after the solid line is flowback, it can be seen that the signals in both the fracture and the matrix are decreasing, demonstrating that the model can effectively draw on portions of the matrix of the model.
Application example (3)
The method for simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir is illustrated by adopting the simple fracture model manufactured in the embodiment 1, an indoor flow-regulating displacement physical simulation experiment and combining the use of a nuclear magnetic resonance instrument. The method comprises the following steps:
p1, cleaning and drying the simple seam model manufactured in the embodiment 1, and then selecting the proppant particles used on site to fill the cracks and the grooves in the model;
p2, filling propping agents into the cracks and the grooves in the model by using a metal gauze to perform leak-proof treatment;
p3, carrying out saturated oil treatment on the sand-filled model;
p4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
p5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before flow regulation displacement;
p6, performing a displacement experiment by using heavy water at one end of the model for making the cracks, injecting a proper amount of plugging agent to plug part of the cracks after a period of time, then continuing to perform the displacement experiment by using the heavy water, and simultaneously performing a real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrum after the flow-regulating displacement (the T2 spectrum in the flow-regulating displacement process is shown in figure 11);
as can be seen from fig. 11, the abscissa of the graph is the relaxation time, the ordinate is the signal amplitude, the curve represents the T2 spectrum of the fracture model, the solid line represents the T2 spectrum before the experiment, and the dotted line represents the T2 spectrum after the experiment. The relaxation time at the intersection of the solid line and the abscissa in the graph is taken as the boundary point of the matrix and the fracture, namely the signal of the oil in the matrix is shown on the left side of the intersection of the solid line and the abscissa, and the signal of the oil in the fracture is shown on the right side. It can be seen that after sufficient saturated oil, oil signals exist in the matrix and the fracture in the model, oil in the fracture is effectively displaced as the displacement is carried out from the fracture end, and meanwhile, some plugging agents are injected to partially plug the fracture after the displacement is carried out for a period of time, so that the matrix part which is not used due to condition limitation is also used, the using degree of the matrix is increased, and the real situation of plugging the fracture in the stratum can be effectively simulated.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (21)
1. A matrix-fracture fluid three-dimensional flow model is characterized in that the model is made of a rock core with the length of L, the model comprises n fractures and m grooves which are distributed in a staggered mode in the axial direction and the radial direction, the fractures and the grooves are respectively located at two ends of the model, and n and m are integers which are not less than 1; the length of the crack is equal to that of the grooves, the length of the crack is a, the shortest distance from each groove to each crack is h, h = L-a, h is larger than 0, and the grooves are manufactured from the side surface of the core.
2. The model of claim 1, wherein the core is a cylinder or a cube.
3. The model of claim 1, wherein the core is sandstone, shale, or carbonate.
4. Model according to claim 1, characterized in that m =2 n.
5. The model of claim 1, wherein the core has a length L of 30-1000 mm.
6. A model according to claim 1, characterized in that the length a of the slits and the grooves is 20-990 mm.
7. The model of claim 1, characterized in that the width b of the slit is 0.5-3 mm.
8. A former according to claim 1, wherein the width c of the groove is 1-5 mm.
9. A method of making a three-dimensional flow model of a matrix-fracture fluid according to any of claims 1 to 8, comprising the steps of:
(1) selecting a rock core with a proper shape, size and lithology as a model making material according to actual needs;
(2) cutting n cracks with the length of a and the width of b at one end of a core with the length of L and the width or the diameter of d, wherein a is less than L, and n is an integer more than or equal to 1;
(3) and manufacturing m grooves with the length of a, the width of c and the depth of e at the other end of the core, so that the shortest distance from each groove to each crack is h, h = L-a and h is greater than 0.
10. The method as claimed in claim 9, wherein in the step (2), n cracks with the length of a and the width of b are cut at one end of the core with the length of L and the width or the diameter of d, wherein a is less than L, and n is an integer more than or equal to 1, and the end face is evenly divided.
11. The method as claimed in claim 9, wherein in step (3), m grooves with length a, width c and depth e are made at the other end of the core in a direction perpendicular to the fracture and through the center of the end face; or
And m grooves with the length of a, the width of c and the depth of e are manufactured in the direction of the angle bisector of two adjacent cracks, so that the shortest distance from each groove to each crack is h, h = L-a, and h > 0.
12. The method as recited in claim 9, wherein the core has a length L of 30-1000mm and a width or diameter d of 30-500 mm.
13. The method of claim 9, wherein the length a of the slit and the groove is 20-990mm, and the width b of the slit is 0.5-3 mm.
14. The method of claim 9, wherein the width c of the groove is 1-5mm and the depth e of the groove is 1-5 mm.
15. The method of claim 9, wherein m =2 n.
16. The application of the matrix-fracture fluid three-dimensional flow model manufactured by the method in the research on the reservoir seepage law of the fractured hydrocarbon reservoir, which is characterized by comprising the steps of simulating and evaluating the reservoir fluid flow law of the fractured hydrocarbon reservoir by using the matrix-fracture fluid three-dimensional flow model and experimental instruments.
17. The use of claim 16, wherein the fluid flow comprises continuous and discontinuous co-directional fluid flow, non-co-directional fluid flow, and transient plug flow modulation of a three-dimensional flow model of a matrix-fracture fluid by a heterogeneous fluid.
18. The use of claim 17, wherein the continuous co-current fluid flow means comprises water flooding, polymer flooding, surfactant flooding, heat injection, and microbial flooding; the discontinuous cocurrent fluid flow mode comprises water-gas alternate injection and/or slug injection; the non-co-directional fluid flow modes include forward fluid loss, blind well fluid exchange, and reverse flowback; the heterogeneous fluid includes a flow modifier carrying solid particles, a flow modifier carrying soft elastomeric particles, and a fluid carrying a transient blocking agent.
19. The use according to claim 17, wherein the method of simulating and evaluating the reservoir fluid flow laws of a fractured hydrocarbon reservoir comprises the steps of:
m1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
m2, carrying out leak-proof treatment on the cracks and grooves in the model by filling proppant;
m3, carrying out saturated oil treatment on the model;
m4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
m5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before displacement;
m6, carrying out a displacement experiment by using heavy water at one end of the model for fracture making, and simultaneously carrying out real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of continuous cocurrent fluid flow in a reservoir of the fractured oil and gas reservoir.
20. The use according to claim 17, wherein the method of simulating and evaluating the reservoir fluid flow laws of a fractured hydrocarbon reservoir comprises the steps of:
s1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
s2, filling propping agents into the cracks and the grooves in the model to perform leak-proof treatment;
s3, placing the model into a holder, and applying confining pressure to simulate the formation pressure;
s4, fluid loss process: performing a fluid loss experiment at one end of the model fracture, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of forward fluid loss in a reservoir of the fractured oil and gas reservoir;
s5, well closing process: closing valves at two ends of the rock core holder after the filtration is finished to realize pressurized blank well, and simultaneously carrying out real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of blank well fluid exchange in a reservoir of the fractured oil-gas reservoir;
s6, a flow-back process: and performing a flowback experiment at one end of the model groove, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real situation of reverse flowback in a fractured reservoir.
21. The use according to claim 17, wherein the method of simulating and evaluating the reservoir fluid flow laws of a fractured hydrocarbon reservoir comprises the steps of:
p1, cleaning and drying the manufactured model, and then selecting proppant particles to fill cracks and grooves in the model;
p2, carrying out leak-proof treatment on the cracks and grooves in the model by filling proppant;
p3, carrying out saturated oil treatment on the model;
p4, placing the saturated oil model into a holder, and applying confining pressure to simulate the formation pressure;
p5, carrying out T2 spectrum test on the model by using a nuclear magnetic resonance instrument to obtain a T2 spectrogram before flow regulation displacement;
p6, performing a displacement experiment by using heavy water at one end of the model for crack formation, injecting a proper amount of plugging agent to plug part of cracks after a period of time, then continuing to perform the displacement experiment by using the heavy water, and simultaneously performing real-time T2 spectrum test on the model by using a nuclear magnetic resonance instrument to simulate and evaluate the real condition of temporary plugging and flow regulation of heterogeneous fluid in a fractured oil and gas reservoir.
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