CN113484116B - Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core - Google Patents
Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core Download PDFInfo
- Publication number
- CN113484116B CN113484116B CN202110805218.4A CN202110805218A CN113484116B CN 113484116 B CN113484116 B CN 113484116B CN 202110805218 A CN202110805218 A CN 202110805218A CN 113484116 B CN113484116 B CN 113484116B
- Authority
- CN
- China
- Prior art keywords
- fracture
- core
- artificial
- rock
- cavity
- 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.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Abstract
The invention relates to the field of oil and gas field development, and discloses a method for preparing an artificial rock core with a fracture-cavity/crack structure in a nondestructive mode and the artificial rock core. The method comprises the following steps: (1) filling a first rock-forming mixture into a core mold; (2) The ellipsoidal capsule and/or strip corresponding to the karst cave and/or crack structure of the actual hydrocarbon reservoir are pressed into the first rock-forming mixture, and after an injection well is arranged, pressing treatment is carried out; (3) Taking out the ellipsoidal capsule body and/or the strip body to form a fracture hole/crack structure; (4) Filling 2-camphene powder into a fracture hole/crack structure, and filling a second rock-forming mixture into a core die; (5) And pressing, solidifying, detecting and pouring the diagenetic mixture to obtain the artificial rock core. The artificial rock core prepared by the method can simultaneously meet the requirements of fine simulation of a complex fracture-cavity/fracture network of an oil and gas reservoir and nondestructive preparation of the artificial rock core.
Description
Technical Field
The invention relates to the field of oil and gas field development, in particular to a method for preparing an artificial rock core with a fracture-cavity/crack structure in a nondestructive mode and the artificial rock core.
Background
At present, global unconventional oil and gas exploration and development are in a high-speed development stage, unconventional oil and gas resources have huge potential, have great strategic significance and gradually become successor resources of conventional oil and gas. Among them, fracture-cavity type carbonate reservoirs and fracture-cavity type tight sandstone reservoirs play an increasingly important role in the development process of oil and gas fields.
The reservoir seepage space of the fracture-cavity type carbonate rock oil-gas reservoir is mainly karst cavities and cracks, and is irregular in three-dimensional space distribution, various in fracture-cavity communication relationship, complex in oil-water relationship and strong in heterogeneity; however, the fractured compact sandstone oil and gas reservoir generally has the characteristics of low porosity and high permeability, and for the reservoir, the core is fragile and has small drilling probability in the coring process due to the development of the fracture, and the acquisition quantity of the natural core is limited. Aiming at the two types of oil and gas reservoirs, the difficulty of describing the actual oil and gas reservoir structure by using the conventional artificial rock core is high, the underground seepage space communication condition cannot be truly simulated, the research progress of related physical simulation experiments is restrained, and the difficulty of fluid seepage characteristic research is also increased. Therefore, the preparation of complex artificial cores (the artificial cores containing fracture-cavity type carbonate and fracture-type compact sandstone) has very important significance.
At present, common complex oil and gas reservoir physical simulation models comprise a one-dimensional physical model, a two-dimensional physical model and a three-dimensional physical model, and key technologies for realizing successful preparation of the models are all core internal joint making technologies. At present, the seam making process in the complex core preparation process mainly comprises the following steps: (1) The slit method is that a slit is formed in the core by a cutting device, so that the shape and distribution of the slit can be effectively controlled, but the cut part without the slit still needs to be glued or filled again, the cementing material used by the slit and the core matrix have larger difference, and the slit process has higher technical requirements on operators and has certain danger; (2) The pressing seam method is to apply external force to generate cracks in the core by using devices such as a triaxial stress loading machine, but the process mainly simulates the fracturing process, and the generated cracks have random distribution, form and other parameters, are difficult to control, and cannot ensure the seam making effect; (3) The split method is to apply normal stress to the core by using a cutter or a puncture needle to generate micro-cracks, but the opening degree of the cracks and the trend of the cracks are difficult to control, and the core is possibly broken; (4) Filling a backing plate, a metal net, zinc sheets, paraffin or salt particles and other materials into a rock core, and realizing joint making by physical or chemical means, wherein: (1) the materials such as the filling backing plate, the metal net, the zinc sheet and the like need to be soaked in the artificial rock core by using acid or alkali solution, but the physicochemical properties of the rock surface can be changed, and the cementing structure of the rock core is damaged to a certain extent, (2) the paraffin needs to be melted by using high temperature, but the paraffin cannot flow out of the rock core completely after being melted, a large amount of paraffin remains in the rock core, (3) the filling salt particles need to be continuously injected into the rock core to ensure that the salt particles are completely dissolved, and under the condition of a large amount of fluid flushing, part of the rock-forming particles can migrate and block in the rock core, so that the rock core is damaged once by the prior methods; (5) Photolithography, namely, a photolithography glass model is used for researching the flow rule of crude oil in karst cave and cracks, but the surface characteristics, wettability and other aspects of glass media have a large gap from an actual reservoir, and the temperature resistance and pressure resistance are poor, so that the seepage characteristics of underground oil reservoir fluid cannot be truly described.
CN104089806a discloses an artificial rock core with multiple pore structures and a preparation method thereof, wherein inorganic salt particles and/or metal sheets are randomly embedded in the preparation of the rock core, and distilled water, acid or alkali liquor are sequentially used for soaking the rock core after solidification, so that the inorganic salt particles and the metal sheets are dissolved to form dissolving holes and cracks. However, the method only uses a soaking method to treat the rock core, so that the dissolution or the reaction is difficult to be completely carried out, and the rock core is damaged once when the rock core is pretreated by distilled water, acid or alkali liquor, so that the experimental effect of physical simulation is greatly influenced.
CN103712843a discloses a method for preparing a fracture-cavity type carbonate rock core, which takes rosin particles and rosin powder as fracture-cavity and crack fillers, and utilizes absolute ethyl alcohol and other organic solvents to dissolve rosin, so as to form effective fracture-cavities and cracks in the rock core. However, the method is difficult to ensure that the rosin is completely dissolved, the residual rosin can cause one-time injury to the core, and the physical and chemical properties of the core can be greatly influenced by treating the core with the rosin and the organic solvent.
CN107831057a discloses an indoor artificial joint making method for a tight sandstone core, which comprises the steps of opening a notch on the end face of the tight sandstone core fixed by a protective sleeve, inserting a joint needle into the notch, and pressurizing for joint making, so that the structural integrity of the joint making core can be ensured. However, the method only considers ensuring the structural integrity of the core, the number of formed cracks is small, and the lengths and the opening degrees of the cracks are difficult to ensure.
In summary, the above preparation method of the complex artificial core is difficult to simultaneously meet the technical requirements of the fine simulation of the complex fracture-cavity/fracture network of the oil and gas reservoir and the nondestructive preparation of the artificial core, so that the experimental result cannot objectively reflect the actual seepage process of the fluid in the underground reservoir.
Therefore, the artificial rock core with the fracture-cavity/fracture structure and the preparation method thereof have important significance, wherein the artificial rock core with the fracture-cavity/fracture structure can simultaneously realize the fine simulation of the complex fracture-cavity/fracture network of the oil and gas reservoir and the nondestructive preparation of the artificial rock core.
Disclosure of Invention
The invention aims to overcome the defect that the existing complex artificial core preparation technology is difficult to simultaneously meet the requirements of complex fracture-cavity/fracture network fine simulation and artificial core nondestructive preparation, and provides a method for preparing an artificial core with a fracture-cavity/fracture structure in a nondestructive manner and an artificial core.
In order to achieve the above object, a first aspect of the present invention provides a method for non-destructively preparing an artificial core having a fracture-cavity/fracture structure, the artificial core including a fracture-cavity type carbonate artificial core and/or a fracture-cavity type tight sandstone artificial core, wherein the method comprises:
(1) Filling a first rock-forming mixture into a core mold;
(2) The ellipsoidal capsule and/or strip corresponding to the karst cave and/or crack structure of the actual hydrocarbon reservoir are pressed into the first rock-forming mixture, and after an injection well is arranged, pressing treatment is carried out;
(3) Taking out the ellipsoidal capsule body and/or the strip-shaped body to form a slot hole/crack structure;
(4) Filling 2-camphene powder into the fracture-cavity/crack structure, and filling a second rock-forming mixture into the core die;
(5) And (3) pressing, solidifying, detecting and pouring the diagenetic mixture to obtain the artificial core with the fracture-cavity/crack structure.
The second aspect of the invention provides an artificial core with a fracture-cavity/fracture structure, which is prepared by the method.
Through the technical scheme, the invention has the following beneficial effects:
(1) According to the invention, the filler 2-borneol powder of the complex fracture-cavity/fracture network in the artificial rock core can be sublimated rapidly under the high temperature condition, and the rock core can be gasified and discharged in the constant temperature curing process of the rock core, so that no damage is caused to the rock core;
(2) The invention can meet the requirements of various and controllable combinations of the fracture holes and the cracks, accurately adjust the quantity, the size, the coordination number and the spatial spreading of the fracture holes and the cracks, quantitatively design the parameters such as the porosity, the permeability and the like of the rock core containing the fracture holes and the cracks, and further realize the effective fine simulation of the complex oil and gas reservoir;
(3) The invention can flexibly arrange the concerned production wells and effectively realize the physical simulation of various development modes of different types of complex oil and gas reservoirs;
(4) The artificial rock core with the fracture-cavity/fracture structure provided by the invention has the advantages of simple and convenient manufacturing process and good repeatability.
Drawings
FIG. 1 is an exploded view of an artificial core mold provided by the present invention;
FIG. 2 is a typical layered pictorial representation of an actual fracture-cave carbonate hydrocarbon reservoir geological section;
FIG. 3 is a schematic view of a longitudinal cross-section of a fracture-cavity type carbonate artificial core prepared in example 1 of the present invention;
FIG. 4 is a schematic longitudinal cross-sectional view of a fracture-cavity type carbonate artificial core prepared in example 1 of the present invention;
FIG. 5 is a three-dimensional schematic view of a fracture-cavity type carbonate artificial core prepared in example 1 of the present invention;
FIG. 6 shows a low field nuclear magnetic resonance T of a representative region of a fracture-cavity type carbonate artificial core prepared in example 1 of the present invention 2 A spectrogram;
FIG. 7 is a low field MRI of a representative region of a fracture-cave carbonate artificial core prepared in example 1 of the present invention;
FIG. 8 is a representative hierarchical pictorial illustration of a geological section of an actual fractured tight sandstone reservoir;
FIG. 9 is a schematic plan view of a fractured-vuggy sandstone artificial core prepared in example 2 of the present invention;
FIG. 10 is a schematic plan view of a fractured-vuggy sandstone artificial core prepared in example 2 of the present invention;
FIG. 11 is a three-dimensional schematic view of a fractured-vuggy sandstone artificial core prepared in example 2 of the present invention;
FIG. 12 is a low field nuclear magnetic resonance T of a representative region of a fractured-vuggy sandstone artificial core prepared in example 2 of the present invention 2 A spectrogram;
FIG. 13 is a low field MRI of a representative region of a fractured-tight sandstone artificial core prepared in example 2 of the present invention;
FIG. 14 is a schematic view showing representative zones of a fracture-cavity type carbonate artificial core prepared in comparative example 1 of the present inventionLow field nuclear magnetic resonance T of a domain 2 A spectrogram;
fig. 15 is a low field mri of a representative region of a fracture-cavity type carbonate artificial core prepared in comparative example 1 of the present invention.
Description of the reference numerals
1-a bottom plate; 2-a main side plate; 3-a secondary side plate; 4-cover plate; 5-long bolts; 6-a nut; 7-artificial core; 8-core matrix; 9-ellipsoidal capsule bodies; 10-coarse bars; 11-fine strips; 12-injection and production well.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The first aspect of the present invention provides a method for preparing an artificial core with a fracture-cavity/fracture structure without damage, the artificial core with the fracture-cavity/fracture structure comprises a fracture-cavity type carbonate artificial core and/or a fracture-type tight sandstone artificial core, wherein the method comprises:
(1) Filling a first rock-forming mixture into a core mold;
(2) The ellipsoidal capsule and/or strip corresponding to the karst cave and/or crack structure of the actual hydrocarbon reservoir are pressed into the first rock-forming mixture, and after an injection well is arranged, pressing treatment is carried out;
(3) Taking out the ellipsoidal capsule body and/or the strip-shaped body to form a slot hole/crack structure;
(4) Filling 2-camphene powder into the fracture-cavity/crack structure, and filling a second rock-forming mixture into the core die;
(5) And (3) pressing, solidifying, detecting and pouring the diagenetic mixture to obtain the artificial core with the fracture-cavity/crack structure.
The inventors of the present invention unexpectedly found that: filling 2-borneol powder into a complex fracture-cavity/crack structure in the artificial rock core, wherein the 2-borneol powder can be sublimated rapidly at high temperature, and the rock core can be gasified and discharged in the constant-temperature curing process of the rock core, so that the rock core is not damaged; the invention can provide various complex fracture holes/cracks combinations and can be controlled, thereby realizing effective fine simulation of complex oil and gas reservoirs; in the artificial rock core preparation process, the concerned production wells can be flexibly arranged at different positions, and the physical simulation of various development modes of different types of complex oil and gas reservoirs is effectively realized; in addition, the artificial rock core with the fracture-cavity/fracture structure provided by the invention has the advantages of simple and convenient manufacturing process and good repeatability.
In the present invention, it is to be noted that: "fracture hole" refers to a fracture + karst hole, wherein the fracture shape is more nearly strip-like and the karst hole shape is more nearly capsule-like.
In addition, the injection and production well is a technical term, and can be understood as an inlet channel and an outlet channel of the artificial rock core.
According to the invention, before the first rock-forming mixture is filled into the core mould in step (1), a core mould and a fracture/hole structure characterization step are also prepared.
Preparing a core mold:
in the invention, the core mold may be made of hastelloy; FIG. 1 is an exploded view of an artificial core mold provided by the present invention; as shown in fig. 1, the bottom plate mainly comprises 1 bottom plate 1, 2 main side plates 2, 2 auxiliary side plates 3 and 1 cover plate 4, wherein the bottom plate is provided with a first positioning groove for fixing 4 side plates, the side surface of the main side plate is provided with a second positioning groove for fixing the auxiliary side plates and a fixed round hole, during assembly, the 2 main side plates are firstly placed in the corresponding first positioning grooves, and then the 2 auxiliary side plates are placed in the corresponding first positioning grooves and the second positioning grooves. After the preliminary fixing is completed, the whole core die is further fastened by using 4 long bolts 5 and 4 pairs of nuts 6 penetrating through the fixing round holes, and the core die assembly is preliminarily completed.
According to the invention, the core mold has the following design dimensions:
length, width, height=300 mm, 300mm, 100mm, volume 9000cm 3 。
According to the invention, preferably, grease is uniformly smeared on the inner wall of the space of the core die, so that the artificial core is prevented from having too strong cementing effect on the core die.
And (3) the structure of the seam hole/crack is depicted:
according to the invention, the geological model data of the actual research block are combined, a geological prototype of the target horizon of the fracture-cavity carbonate rock-hydrocarbon reservoir is selected, and a representative fracture-cavity structure is depicted, so that the complex artificial core approaches to the actual hydrocarbon reservoir in aspects of fracture-cavity ratio, fracture-cavity density and the like.
According to the invention, the geological model data of the actual research block are combined, a geological prototype of the target horizon of the fractured tight sandstone hydrocarbon reservoir is selected, and a representative fracture structure is depicted, so that the complex artificial core approaches to the actual hydrocarbon reservoir in terms of fracture distribution, fracture number and the like.
According to the invention, in step (1), a core material, i.e. a rock-forming mixture, is prepared, and a first rock-forming mixture is filled into the core mould.
In the present invention, the permeability of the core matrix of the target zone is 0.5X10 -3 μm 2 Up to 6.0X10 -3 μm 2 And determining a core matrix material, namely a rock-forming mixture formula according to experimental results of determining the mineral composition of the natural core and core permeability requirements.
According to the invention, the first and second rock-forming mixtures are identical, each comprising a rock-forming mineral powder and/or a cementing agent.
According to the invention, the diagenetic mixture comprises diagenetic mineral powder and/or cementing agent; preferably, the diagenetic mixture is diagenetic mineral powder and a cementing agent; more preferably, the diagenetic mineral powder is selected from one or more of carbonate minerals (calcite and dolomite) and/or non-carbonate minerals (quartz, feldspar and clay); still more preferably, the diagenetic mineral powder is selected from carbonate minerals (calcite and dolomite) and non-carbonate minerals (quartz, feldspar and clay).
More preferably, according to the present invention, the cement comprises bisphenol a type epoxy resin, a curing agent and a diluent. In the invention, the content of bisphenol A epoxy resin is 65-87wt percent, the content of curing agent is 10-25wt percent and the content of diluent is 3-10wt percent based on the total weight of the cementing agent; preferably, the bisphenol A type epoxy resin is contained in an amount of 72 to 80wt%, the curing agent is contained in an amount of 15 to 20wt% and the diluent is contained in an amount of 5 to 8wt% based on the total weight of the cement.
According to the invention, the content of the diagenetic mineral powder is 75-85wt% and the content of the cementing agent is 15-25wt%, based on the weight of the first diagenetic mixture or the second diagenetic mixture; preferably, the diagenetic mineral powder is present in an amount of 82 to 85wt% and the cementing agent is present in an amount of 15 to 18wt% based on the weight of the first diagenetic mixture or the second diagenetic mixture.
According to the invention, the volume of the first rock-forming mixture is 30-70vol% and the volume of the second rock-forming mixture is 30-70vol% based on the total volume of the core mould; preferably, the volume of the first rock-forming mixture is 45-55vol% and the volume of the second rock-forming mixture is 45-55vol% based on the total volume of the core mold; more preferably, the volume of the first rock-forming mixture is 50vol% and the volume of the second rock-forming mixture is 50vol% based on the total volume of the core mold.
According to the invention, the diagenetic mixture is stirred uniformly and is screened by a 20-mesh screen for standby. Preferably, the diagenetic mixture composed of diagenetic mineral powder and cementing agent is equally divided into 6-8 parts, and 3-4 parts of diagenetic mixture, namely the first diagenetic mixture, is uniformly filled into the core die to 1/2 of the design height.
According to the invention, in the step (2), the ellipsoidal capsule body comprises a middle part and end parts connected with the middle part, wherein the middle part is a cylinder, and the end parts are hemispheres.
According to the invention, the radius of the hemispheroids is 15-20mm; preferably, the radius of the hemispherical body has two specifications of 15mm and 20mm, and the length of the capsule body is self-processed according to the physical simulation requirement.
According to the invention, the radius of the strip is 1-2mm; preferably, the radius of the strip body has two specifications of 1mm and 2mm, the two conditions of fine cracks and coarse cracks are simulated respectively, and the length of the strip body is processed according to the physical simulation requirement.
According to the invention, in order to simulate the development modes of different types of complex oil and gas reservoirs, the invention is realized by arranging injection and production wells at different positions of an artificial rock core with a fracture hole/crack structure, wherein the inner radius of the injection and production well is 1-4mm, and the outer radius of the injection and production well is 1.5-4.5mm; preferably, the injection well and the production well are steel tubules, the inner radius is 2-2.5mm, the outer radius is 2.5-3mm, and the length of the injection well and the production well is automatically processed according to the layout position.
According to the invention, the ellipsoidal capsule body, the strip body and the injection well are all made of metal materials; preferably, the ellipsoidal capsule body and the strip body are made of steel materials and can be processed in a customized size.
According to the present invention, in step (2), the conditions of the pressing treatment include: the temperature is 20-45 ℃, the pressure is 5-30MPa, and the time is 0.5-2.5h; preferably, the temperature is 25-30 ℃, the pressure is 10-20MPa, and the time is 1-2h.
According to the invention, in the step (3), after the diagenetic mixture in the core die has certain strength, all ellipsoidal capsules and strips are taken out to form a complex fracture-cavity/fracture structure.
According to the invention, in the step (4), sufficient 2-borneol powder is filled into the fracture hole/crack, the mass of the added 2-borneol powder is recorded, and the core mould is continuously filled with the rest of the diagenetic mixture, namely the second diagenetic mixture, uniformly to the designed height. In addition, in the present invention, the inventors of the present invention unexpectedly found that: the 2-borneol powder is relatively stable at room temperature and has certain strength (during core pressing treatment), can be completely sublimated at high temperature (during core curing treatment), and the 2-borneol powder sublimates into physical change at high temperature. In the present invention, 2-borneol powder was purchased from Shanghai Ala Biotechnology Co., ltd, purity 96%, melting point 176-180 ℃.
According to the present invention, in step (5), the conditions of the press treatment include: the temperature is 20-45 ℃, the pressure is 5-30MPa, and the time is 0.5-2.5h; preferably, the temperature is 25-30 ℃, the pressure is 10-20MPa, and the time is 1-2h.
According to the invention, in the step (5), after the solidification treatment, the 2-borneol powder sublimates, and a complex fracture hole/crack structure corresponding to a karst hole and/or crack structure of an actual oil and gas reservoir is formed inside the artificial rock core.
According to the present invention, the conditions of the curing treatment include: the temperature is 60-120 ℃ and the time is 24-60h; preferably, the temperature is 80-90 ℃ and the time is 30-36h.
According to the invention, in step (5), the method of detection comprises a mass difference detection method and/or a nuclear magnetic detection method.
In the present invention, the quality difference detection method includes formula (a), formula (b), formula (c) and formula (d):
N＝(m 1 -m 2 )/m 0 formula (a);
wherein in formula (a), m 0 2-camphor powder mass for filling the complex fracture hole/crack structure; m is m 1 The total mass of the artificial core with the fracture-hole/fracture structure before curing treatment; m is m 2 The total mass of the artificial core with the fracture-hole/crack structure after the curing treatment is as follows;
V r ＝V-V w formula (b);
wherein in the formulas (b), (c) and (d), V is the total volume of the artificial core with the fracture-hole/fracture structure; v (V) r An effective volume of the artificial core with a fracture-hole/fracture structure; v (V) c For the manufacture ofThe volume of the ellipsoidal capsule body for the hole; v (V) f A volume of the seam making strip; v (V) w A volume for the injection well;
is the karst cave porosity; />
Is fracture porosity.
According to the present invention, in step (5), the casting treatment conditions include: the temperature is 20-45 ℃ and the time is 36-72h; preferably, the temperature is 25-30 ℃ and the time is 48-60h.
According to the invention, casting is performed by casting materials, wherein the casting materials comprise epoxy resin and curing agent; preferably, when casting is performed by using casting materials, the casting thickness is 20-30mm.
According to the invention, the content of the epoxy resin is 75-90wt% and the content of the curing agent is 10-25wt% based on the total weight of the casting material; preferably, the epoxy resin is 80-85wt% and the curing agent is 15-20wt% based on the total weight of the casting material.
The second aspect of the invention provides an artificial core with a fracture-cavity/fracture structure, which is prepared by the method.
According to the invention, the compressive strength of the artificial core with the fracture-cavity/fracture structure is 2-5MPa, preferably 3-4MPa.
According to the invention, the artificial core with the fracture-cavity/fracture structure comprises the following parts: matrix material, joint making material, well distributing material and pouring material. The matrix material of the core mainly comprises different kinds of diagenetic mineral powder (carbonate minerals such as calcite, dolomite and the like and non-carbonate minerals such as quartz, feldspar, clay and the like) and cementing agent, and firstly, mineral composition analysis is carried out on a natural core taken from a target complex oil and gas reservoir, and specific mineral components and proportions of the natural core are determined; fully and uniformly stirring different diagenetic mineral powders and cementing agents according to the determined mass percentage ratio, and sieving for later use; the joint-making material of the core mainly comprises complex joint holes/crack dies (containing ellipsoidal capsule bodies and strip bodies) with different specifications and sizes and 2-camphene powder; the well-setting material of the core is mainly equal-diameter metal tubules with different lengths; the casting material of the core is mainly epoxy resin and curing agent.
According to a preferred mode of the present invention, a method for preparing an artificial core having a fracture-hole/fracture structure without damage includes:
step one: assembled core mould
According to the design and assembly sequence of fig. 1, the bottom plate, the main side plate, the auxiliary side plate and the cover plate of the core die are assembled in sequence, and the inner wall of the space of the core die is uniformly smeared with grease for later use.
Step two: hole/crack characterization
And selecting a geological prototype of the target horizon of the complex hydrocarbon reservoir by combining with geological model data of the actual research block, and describing a representative complex fracture hole/fracture structure, so that the artificial core with the fracture hole/fracture structure is close to the actual hydrocarbon reservoir in aspects of fracture hole ratio, fracture hole density, fracture distribution, fracture number and the like.
Step three: preparation of core material
The artificial rock core with the fracture-cavity/fracture structure comprises the following parts: matrix material, joint making material, well distributing material and pouring material. The matrix material of the core mainly comprises different kinds of diagenetic mineral powder and cementing agent, and firstly, mineral composition analysis is carried out on a natural core taken from a target complex oil and gas reservoir, and specific mineral components and proportions of the natural core are determined; fully and uniformly stirring different diagenetic mineral powders (carbonate minerals such as calcite, dolomite and the like and non-carbonate minerals such as quartz, feldspar, clay and the like) and cementing agents according to the determined mass percentage ratio, and sieving for later use; the joint-making material of the core mainly comprises complex joint holes/crack dies (containing ellipsoidal capsule bodies and strip bodies) with different specifications and sizes and 2-camphene powder; the well-setting material of the core is mainly equal-diameter metal tubules with different lengths; the casting material of the core is mainly epoxy resin and curing agent.
Step four: artificial core filling
The design height of the core is h, a diagenetic mixture consisting of diagenetic mineral powder and cementing agent is equally divided into n parts (n=6 or 8), and the n parts are sequentially and uniformly filled into a core die to a filling height h/2. According to the actual oil and gas reservoir fracture hole/crack structure, designing a corresponding complex fracture hole/crack combination scheme, respectively pressing complex fracture hole/crack dies with different specifications and sizes in a joint-making material into a rock-forming mixture according to the design positions, arranging injection and production wells at the corresponding positions, carrying out compression treatment for 1-2h, and taking out all the complex fracture hole/crack dies after the first rock-forming mixture in the dies has certain strength to form the complex fracture hole/crack structure. Filling sufficient 2-borneol powder into the complex slot/crack, recording the mass of the added 2-borneol powder, and recording as m 0 . And continuously and uniformly filling the second rock-forming mixture into the core die to the designed height h.
Step five: artificial core pressing
Covering a core die cover plate, placing the filled core die on a special hydraulic press, pressing for 1-2h according to the set stable pressure, taking down the core die cover plate, weighing the total mass of the artificial core with a fracture-cavity/fracture structure for 3 times before curing treatment, and recording the average value of the total mass as m 1 。
Step six: artificial core curing
Placing the pressed core mould and the artificial core in a vacuum-pumped incubator, setting the curing temperature to 80-90 ℃, and carrying out constant-temperature treatment for 30-36h, so that the artificial core with a fracture hole/crack structure is fully cured, and simultaneously 2-camphene powder serving as a complex fracture hole/crack filler is fully sublimated in the temperature range, so that a complete complex fracture hole/crack structure can be formed in the artificial core.
Step seven: hole/crack detection
(1) Quality difference detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembled, the total mass of the solidified artificial rock core with the fracture-cavity/crack structure is weighed for 3 times, and the average value of the total mass is recorded as m 2 . The structural integrity N of the complex fracture hole/crack is calculated according to the following calculation formula：
N＝(m 1 -m 2 )/m 0 ；
Wherein m is 0 2-borneol powder mass for filling complex fracture-cavity/crack structure; m is m 1 The total mass of the artificial rock core with the fracture-hole/fracture structure before curing treatment; m is m 1 Is the total mass of the artificial core with the fracture-hole/fracture structure after the curing treatment. N is in the range of 0.8-1.0, and the closer the N value is to 1.0, the more complete the sublimation of 2-camphene powder in the complex fracture hole/crack structure is, namely the more complete the complex fracture hole/crack structure in the artificial rock core is.
At this time, the karst cave porosity of the artificial core having the fracture-cave/fracture structure
Crack porosity->
Quantitative calculation can be performed, and the calculation formula is as follows:
V r ＝V-V w ；
wherein V is the total volume of the artificial core with the fracture-hole/fracture structure; v (V) r An effective volume of the artificial core with a fracture-hole/fracture structure; v (V) c Is the volume of an ellipsoidal capsule body for making holes; v (V) f The volume of the strip body for making the seam; v (V) w Is the volume of the injection well.
(2) Nuclear magnetic detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembled, and the representative region of the artificial rock core with the fracture-cavity/crack structure is scanned by means of a large-aperture nuclear magnetic resonance imaging analyzer, so that the prepared artificial rock core with the fracture-cavity/crack is obtainedT of artificial rock core of structure 2 And (3) the spectrogram is used for further determining the distribution rule of the complex fracture-cavity/crack structure in the core, performing nuclear magnetic resonance imaging treatment on the scanned core, and accurately identifying the spatial structures such as cracks, karst cavities and the like in the core, so that nondestructive detection of the complex fracture-cavity/crack is realized.
Step eight: artificial core casting
After the detection is qualified, uniformly pouring the whole rock core by using a casting material outside the rock core, and performing molding treatment at 25-30 ℃ for 48-60 hours to form the pouring fracture-cavity type/crack type artificial rock core with certain compressive strength.
The present invention will be described in detail by examples.
In the following examples and comparative examples:
large aperture nuclear magnetic resonance imaging analyzer: available from macroMR12-150H-I, model number N.Y. analytical instruments, inc., of Suzhou.
Example 1
The embodiment is to explain a nondestructive preparation method of a fracture-cavity type carbonate rock artificial core and the fracture-cavity type carbonate rock artificial core.
Step one: assembled core mould
As shown in fig. 1, a core mold is assembled; specifically: the core die is made of hastelloy and mainly comprises 1 bottom plate 1, 2 main side plates 2, 2 auxiliary side plates 3 and 1 cover plate 4, wherein the bottom plate is provided with first positioning grooves for fixing the 4 side plates, the side surfaces of the main side plates are provided with second positioning grooves for fixing the auxiliary side plates and fixed round holes, the 2 main side plates are arranged in the corresponding first positioning grooves during assembly, and the 2 auxiliary side plates are arranged in the corresponding first positioning grooves and the second positioning grooves. After preliminary fixing is completed, the whole core die is further fastened by utilizing 4 long bolts 5 and 4 pairs of nuts 6 penetrating through the fixing round holes, the core die is assembled preliminarily, grease is uniformly smeared on the inner wall of the space of the core die, and the cementing effect of the artificial core on the core die is prevented from being too strong.
Step two: hole structure is carved
And selecting a geological prototype of a target horizon of the fracture-cavity carbonate hydrocarbon reservoir by combining geological model data of an actual research block, and describing a representative fracture-cavity structure to enable the fracture-cavity carbonate artificial core to approach the actual hydrocarbon reservoir in aspects of fracture-cavity ratio, fracture-cavity density and the like, wherein as shown in fig. 2, fig. 2 is a typical layered drawing of geological slices of the actual fracture-cavity carbonate hydrocarbon reservoir.
Step three: preparation of core material
The average permeability of the core matrix 8 of the target zone was 0.8x10 -3 μm 2 According to the experimental result of measuring the mineral composition of the natural rock core and the rock core permeability requirement, the formula of the rock core matrix material is determined as follows: 85wt% of diagenetic mineral powder and 15wt% of cementing agent, wherein the diagenetic mineral powder comprises the following components: 87.5wt% calcite, 3.6wt% dolomite, 2.2wt% quartz, 0.8wt% feldspar and 5.9wt% clay; the cementing agent comprises the following components: 75wt% bisphenol A type epoxy resin, 20wt% curing agent and 5wt% diluent. The ellipsoidal capsule 9 made of core hole-making/sewing material and the strips 10 and 11 are made of steel materials and can be processed in a customized size, and in the embodiment, the ellipsoidal capsule is regular in shape and comprises a middle part and an end part connected with the middle part, namely, the middle part is a cylinder, the end part is a hemisphere, the radius of the hemisphere is 15mm and 20mm, and the length of the capsule is automatically processed according to the physical simulation requirement; the radius of the strip body is 1mm and 2mm, the two conditions of the fine crack and the coarse crack are respectively simulated, and the length of the strip body is automatically processed according to the physical simulation requirement. In order to simulate the development modes of different fracture-cavity carbonate rock hydrocarbon reservoirs, the invention is realized by arranging injection and production wells 12 at different positions of the fracture-cavity hydrocarbon reservoirs, wherein the injection and production wells are steel tubules, the inner radius is 2.5mm, the outer radius is 3mm, and the lengths of the injection and production wells are automatically processed according to the arrangement positions. The formula of the core external pouring material is as follows: 80wt% of epoxy resin and 20wt% of curing agent.
The parameters of the hole making/slotting material of the artificial rock core of the fracture-cavity type carbonate rock in the embodiment are shown in table 1.
TABLE 1
| Sequence number | Type(s) | Quantity (number) | Radius (mm) | Length (mm) | Volume (cm) 3 ) |
| 1 | |
1 | 20.0 | 80.0 | 83.78 |
| 2 | |
1 | 20.0 | 60.0 | 58.64 |
| 3 | |
1 | 15.0 | 50.0 | 28.27 |
| 4 | |
1 | 15.0 | 40.0 | 21.21 |
| 5 | |
1 | 15.0 | 36.0 | 18.38 |
| 6 | Strip-shaped |
1 | 2.0 | 200.0 | 2.51 |
| 7 | Strip-shaped |
1 | 2.0 | 180.0 | 2.26 |
| 8 | Strip-shaped body | 2 | 2.0 | 150.0 | 3.77 |
| 9 | Strip-shaped |
1 | 2.0 | 100.0 | 1.26 |
| 10 | Strip-shaped body | 6 | 1.0 | 150.0 | 2.83 |
| 11 | Strip-shaped |
1 | 1.0 | 100.0 | 0.31 |
Step four: artificial core filling
The design size of the core is as follows: length, width, height=300 mm, 300mm, 100mm, volume 9000cm 3 18073.1g of calcite, 743.6g of dolomite, 454.4g of quartz, 165.2g of feldspar and 1218.6g of clay are sequentially weighed and uniformly mixed to prepare rock mineral powder, 2733.8g of bisphenol A type epoxy resin, 729.0g of curing agent and 182.3g of diluent are sequentially weighed and uniformly mixed to prepare cementing agent, and then the cementing agent is poured into the rock mineral powder to be uniformly stirred and then screened by a 20-mesh screen for standby. The method comprises the steps of equally dividing a diagenetic mixture formed by diagenetic mineral powder and a cementing agent into 8 parts, and firstly, uniformly filling 4 parts of a first diagenetic mixture into a core die until the design height is 1/2, namely 50mm. According to the designed fracture and karst cave combination scheme, ellipsoidal capsule bodies, strip bodies and injection and production wells with different specifications are pressed into a diagenetic mixture according to the design positions, 10MPa of stable pressure is applied at 25 ℃ for pressing for 2 hours, after the diagenetic mixture in a mould has certain strength, all ellipsoidal capsule bodies and strip bodies are taken out to form a complex fracture-cave space structure, as shown in fig. 3 and 4, fig. 3 is a longitudinal section three-dimensional schematic diagram of the fracture-cave type carbonate rock artificial core prepared in the embodiment 1; FIG. 4 is a longitudinal cross-section of an artificial core of fracture-cavity carbonate rock prepared in example 1 of the present invention Schematic diagram. Filling sufficient 2-borneol powder into the complex cracks and karst cave, and recording the mass m of the added 2-borneol powder 0 The core mold was continuously filled with the remaining 4 parts of the second rock-forming mixture uniformly to a design height of 100mm at 221.0 g.
The parameters of the artificial rock core well-laying material of the fracture-cavity type carbonate rock of the embodiment are shown in table 2.
TABLE 2
Step five: artificial core pressing
Covering a core mould cover plate 4 above the diagenetic mixture, placing the filled core mould on a special hydraulic press, applying 10MPa steady pressure for pressing for 2h, taking down the core mould cover plate, weighing the total mass of the artificial core of the fracture-cavity carbonate rock for 3 times before curing treatment, and recording m 1 24521.6g.
Step six: artificial core curing
Placing the pressed core mold and the artificial core in a vacuum-pumped incubator, setting the curing temperature to 80 ℃, and carrying out constant-temperature treatment for 36 hours to fully cure the artificial core of the fracture-cavity carbonate rock, wherein the 2-borneol powder filling the fracture and the karst cavity can be sublimated completely at the temperature, and a complete complex fracture-cavity structure is formed in the core, as shown in fig. 5, and fig. 5 is a three-dimensional schematic diagram of the artificial core of the fracture-cavity carbonate rock prepared in the embodiment 1 of the invention.
Step seven: detection of fracture-cavity structure
(1) Quality difference detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembled, the total mass of the fracture-cavity type carbonate rock artificial rock core after solidification treatment is weighed for 3 times, and m is recorded 2 24301.9g. Calculating the structural integrity N of the fracture-cavity, wherein the calculation formula is as follows:
N＝(m 1 -m 2 )/m 0 ＝(24521.6g-24301.9g)/221.0g＝0.99；
wherein m is 0 2-camphene for filling complex seam hole structureThe mass of the powder; m is m 1 The total mass of the fracture-cavity type carbonate rock artificial core before curing treatment; m is m 2 The total mass of the fracture-cavity type carbonate rock artificial core after the curing treatment is obtained.
The calculation result shows that the N value is 0.99 and is close to the theoretical maximum value of 1, which indicates that 2-camphene powder in the fracture-cavity structure is completely sublimated, namely the complex fracture-cavity structure in the artificial rock core is complete.
At this time, the karst cave porosity of the artificial core of the fracture-cave type carbonate rock
Crack porosity->
Quantitative calculation can be performed, and the calculation formula is as follows:
V r ＝V-V w ；
wherein V is the total volume of the fracture-cavity type carbonate rock artificial core; v (V) r The effective volume of the artificial rock core of the fracture-cavity type carbonate rock; v (V) c Is the volume of an ellipsoidal capsule body for making holes; v (V) f The volume of the strip body for making the seam; v (V) w Is the volume of the injection well.
The porosity parameters of the artificial rock core of the fracture-cavity type carbonate rock of the embodiment are shown in table 3.
TABLE 3 Table 3
(2) Nuclear magnetic detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembledThe method comprises the steps of scanning a representative region of an artificial rock core by means of a large-aperture nuclear magnetic resonance imaging analyzer to obtain a T-shaped artificial rock core of the prepared fracture-cavity carbonate rock 2 A spectrogram.
FIG. 6 shows a low field nuclear magnetic resonance T of a representative region of a fracture-cavity type carbonate artificial core prepared in example 1 of the present invention 2 A spectrogram; from fig. 6, it can be derived that: t (T) 2 The spectrogram curve is in bimodal distribution, the small peak represents the core matrix, the large peak represents the fracture-cavity structure, and the relaxation time and peak area corresponding to the large peak are far longer than those of the small peak, so that the distribution rule of the complex fracture-cavity structure in the artificial core is obvious.
FIG. 7 is a low field MRI of a representative region of a fracture-cave carbonate artificial core prepared in example 1 of the present invention; from fig. 7, it can be derived that: the karst cave structure exists in the middle area of the artificial rock core, and obvious crack structures are visible at the center axis of the whole rock core, so that the space structures of cracks, karst cave and the like in the artificial rock core are clear and are consistent with the earlier design scheme.
Step eight: artificial core casting
And after the fracture-cavity structure is detected to be qualified, uniformly pouring the whole artificial rock core by using a casting material outside the rock core, wherein the pouring thickness is 20mm, and performing molding treatment at 25 ℃ for 60 hours to form the pouring fracture-cavity type carbonate rock artificial rock core with the compressive strength of 3 MPa.
Example 2
The embodiment aims at explaining a nondestructive preparation method of the fractured compact sandstone artificial core and the fractured compact sandstone artificial core.
Step one: assembled core mould
As shown in fig. 1, a core mold is assembled; specifically: the core die is made of hastelloy and mainly comprises 1 bottom plate 1, 2 main side plates 2, 2 auxiliary side plates 3 and 1 cover plate 4, wherein the bottom plate is provided with first positioning grooves for fixing the 4 side plates, the side surfaces of the main side plates are provided with second positioning grooves for fixing the auxiliary side plates and fixed round holes, the 2 main side plates are arranged in the corresponding first positioning grooves during assembly, and the 2 auxiliary side plates are arranged in the corresponding first positioning grooves and the second positioning grooves. After preliminary fixing is completed, the whole core die is further fastened by utilizing 4 long bolts 5 and 4 pairs of nuts 6 penetrating through the fixing round holes, the core die is assembled preliminarily, grease is uniformly smeared on the inner wall of the space of the core die, and the cementing effect of the artificial core on the core die is prevented from being too strong.
Step two: crack structure characterization
Selecting a geological prototype of a target horizon of a fracture-type tight sandstone hydrocarbon reservoir by combining geological model data of an actual research block, and describing a representative fracture structure, so that the fracture-type tight sandstone artificial core approaches to the actual hydrocarbon reservoir in aspects of fracture distribution, fracture number and the like; as shown in fig. 8, fig. 8 is a typical layered pictorial drawing of a geological section of an actual fractured tight sandstone reservoir.
Step three: preparation of core material
The permeability of the core matrix 8 of the target zone was 0.1X10 -3 μm 2 According to the experimental result of measuring the mineral composition of the natural rock core and the rock core permeability requirement, the formula of the rock core matrix material is determined as follows: 82wt% of a diagenetic mineral powder and 18wt% of a cementing agent, wherein the diagenetic mineral powder has the formula: 2.9wt% calcite, 1.1wt% dolomite, 42.5wt% quartz, 46.0wt% feldspar and 7.5wt% clay; the cementing agent comprises the following components: 80wt% of bisphenol A type epoxy resin, 15wt% of curing agent and 5wt% of diluent. The core joint-making material strips 10 and 11 are made of steel materials and can be processed in a customized size, in the embodiment, the radius of each strip is 1mm and 2mm, the two conditions of fine cracks and coarse cracks are respectively simulated, and the lengths of the strips are automatically processed according to the physical simulation requirements. In order to simulate the development modes of different fracture type tight sandstone oil and gas reservoirs, the invention is realized by arranging injection and production wells 12 at different positions, wherein the injection and production wells are steel tubules, the inner radius is 2.5mm, the outer radius is 3mm, and the length of the injection and production wells is automatically processed according to the arrangement positions. The formula of the core external pouring material is as follows: 80wt% of epoxy resin and 20wt% of curing agent.
The parameters of the artificial core joint-making material of the fractured tight sandstone of this example are shown in table 4.
TABLE 4 Table 4
| Sequence number | Type(s) | Quantity (number) | Radius (mm) | Length (mm) | Volume (cm) 3 ) |
| 1 | Strip-shaped |
1 | 2.0 | 220.0 | 2.76 |
| 2 | Strip-shaped |
1 | 2.0 | 210.0 | 2.64 |
| 3 | Strip-shaped |
1 | 2.0 | 200.0 | 2.51 |
| 4 | Strip-shaped body | 2 | 2.0 | 180.0 | 4.52 |
| 5 | Strip-shaped |
1 | 2.0 | 160.0 | 2.01 |
| 6 | Strip-shaped |
1 | 2.0 | 150.0 | 1.88 |
| 7 | Strip-shaped body | 2 | 2.0 | 100.0 | 2.51 |
| 8 | Strip-shaped body | 3 | 1.0 | 160.0 | 1.51 |
| 9 | Strip-shaped body | 4 | 1.0 | 150.0 | 1.88 |
| 10 | Strip-shaped body | 2 | 1.0 | 140.0 | 0.88 |
| 11 | Strip-shaped body | 2 | 1.0 | 100.0 | 0.63 |
Step four: artificial core filling
The design size of the core is as follows: length, width, height=300 mm, 300mm, 100mm, volume 9000cm 3 567.2g of calcite, 215.1g of dolomite, 8311.7g of quartz, 8996.2g of feldspar and 1466.8g of clay are sequentially weighed and uniformly mixed to prepare rock mineral powder, 3434.4g of bisphenol A type epoxy resin, 644.0g of curing agent and 214.7g of diluent are sequentially weighed and uniformly mixed to prepare cementing agent, and the cementing agent is poured into the rock mineral powder to be uniformly stirred and then screened by a 20-mesh screen for standby. The method comprises the steps of equally dividing a diagenetic mixture formed by diagenetic mineral powder and a cementing agent into 8 parts, and firstly, uniformly filling 4 parts of a first diagenetic mixture into a core die until the design height is 1/2, namely 50mm. According to the designed crack combination scheme, pressing strip bodies with different specifications and injection and production wells into a diagenetic mixture according to the design positions, applying 15MPa stable pressure at 25 ℃ for pressing for 1h, and taking out all strip bodies after the diagenetic mixture in the die has certain strength to form a complex crack space structure; as shown in fig. 9 and 10, fig. 9 is a schematic plan-sectional three-dimensional view of a fractured-vuggy sandstone artificial core prepared in example 2 of the present invention; FIG. 10 is a schematic illustration of an embodiment of the present invention 2, a schematic plan section of the prepared fractured compact sandstone artificial core; filling sufficient 2-camphene powder into the complex cracks, and recording the mass m of the added 2-camphene powder 0 The core mold was continuously filled with the remaining 4 parts of the second rock-forming mixture uniformly to a design height of 100mm at 23.5 g.
The parameters of the artificial core well-laying material of the fractured tight sandstone of this example are shown in Table 5.
TABLE 5
Step five: artificial core pressing
Covering a core mould cover plate 4 above the diagenetic mixture, placing the filled core mould on a special hydraulic press, applying 15MPa steady pressure for pressing for 1h, taking down the core mould cover plate, weighing the total mass of the fractured compact sandstone artificial core before curing treatment for 3 times, and recording m 1 23873.5g.
Step six: artificial core curing
Placing the pressed core mold and the artificial core in a vacuum-pumped incubator, setting the curing temperature to 90 ℃, and carrying out constant-temperature treatment for 36 hours to fully cure the crack type compact sandstone artificial core, wherein the 2-borneol powder filling the cracks can be sublimated completely at the temperature, and a complete complex crack structure is formed in the core, as shown in fig. 11, and fig. 11 is a three-dimensional schematic diagram of the crack type compact sandstone artificial core prepared in the embodiment 2 of the invention.
Step seven: crack structure detection
(1) Quality difference detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembled, the total mass of the crack type compact sandstone artificial rock core after solidification treatment is weighed for 3 times, and m is recorded 2 23850.4g. The structural integrity N of the crack is calculated according to the following formula:
N＝(m 1 -m 2 )/m 0 ＝(23873.5g-23850.4g)/23.5g＝0.98；
wherein m is 0 2-camphor powder mass for filling complex crack structure; m is m 1 The total mass of the fractured compact sandstone artificial core before curing treatment; m is m 2 The total mass of the crack type compact sandstone artificial core after the curing treatment is obtained.
The calculation result shows that the N value is 0.98 and is close to the theoretical maximum value of 1, which indicates that the sublimation of the 2-borneol powder in the crack structure is close to complete, namely the complex crack structure in the artificial rock core is complete.
At this time, the fracture porosity of the fractured compact sandstone artificial core
Quantitative calculation can be performed, and the calculation formula is as follows:
V r ＝V-V w ；
wherein V is the total volume of the fractured compact sandstone artificial core; v (V) r The effective volume of the artificial core of the fractured compact sandstone; v (V) f The volume of the strip body for making the seam; v (V) w Is the volume of the injection well.
The porosity parameters of the fractured tight sandstone artificial core of this example are shown in table 6.
TABLE 6
(2) Nuclear magnetic detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembled, and a large-aperture nuclear magnetic resonance imaging analyzer is used for scanning a representative area of the artificial rock core to obtain the T-shaped fractured compact sandstone artificial rock core 2 A spectrogram.
FIG. 12 is a low field nuclear magnetic resonance T of a representative region of a fractured-vuggy sandstone artificial core prepared in example 2 of the present invention 2 A spectrogram; from fig. 12, it can be derived that:T 2 the spectrogram curve is in bimodal distribution, the small peak represents the core matrix, the large peak represents the crack structure, and the relaxation time and peak area corresponding to the large peak are far longer than those of the small peak, so that the distribution rule of the complex crack structure in the artificial core is obvious.
FIG. 13 is a low field MRI of a representative region of a fractured-tight sandstone artificial core prepared in example 2 of the present invention; from fig. 13, it can be derived that: obvious crack structures are visible at the center axis of the artificial rock core, which shows that the internal crack structures of the artificial rock core are clear and are consistent with the prior design scheme.
Step eight: artificial core casting
And after the crack structure is detected to be qualified, uniformly pouring the whole artificial core by using a core external pouring material, wherein the pouring thickness is 30mm, and performing molding treatment at 25 ℃ for 60 hours to form the pouring crack type compact sandstone artificial core with the compressive strength of 4 MPa.
Comparative example 1
A fracture-cavity type carbonate rock artificial core was prepared in the same manner as in example 1, and in comparative example 1, paraffin, which is a common filler for heat-cured cores, was provided, and the process was the same as that of 2-camphor powder, except for the material; specifically, the difference is that: "2-camphene powder" was replaced with "paraffin wax" which was purchased from Chengdu Shu plasticization Co., ltd, semi-refined wax, oil content 1.8%, melting point 58 ℃.
In addition, in step four: artificial core filling
Record the mass m of the paraffin wax added 0 183.0g.
Step five: artificial core pressing
Weighing the total mass of the fracture-cavity type carbonate rock artificial core for 3 times before curing treatment, and recording m 1 24483.0g.
Step six: artificial core curing
The solid paraffin in the artificial rock core cracks and karst cave has fluidity at 80 ℃, but cannot flow out of the artificial rock core completely, so that a large amount of paraffin remains in the space structure of the inner fracture cave of the rock core.
Step seven: detection of fracture-cavity structure
(1) Quality difference detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembled, the total mass of the fracture-cavity type carbonate rock artificial rock core after solidification treatment is weighed for 3 times, and m is recorded 2 24395.9g. Calculating the structural integrity N of the fracture-cavity, wherein the calculation formula is as follows:
N＝(m 1 -m 2 )/m 0 ＝(24483.0g-24395.9g)/183.0g＝0.48；
wherein m is 0 The quality of the solid paraffin for filling the fracture-cavity structure is improved; m is m 1 The total mass of the fracture-cavity type carbonate rock artificial core before curing treatment; m is m 2 The total mass of the fracture-cavity type carbonate rock artificial core after the curing treatment is obtained.
The calculation result shows that the N value is 0.48 and is not close to the theoretical maximum value 1, which indicates that the clearance of the solid paraffin in the fracture-cavity structure is incomplete, namely the complex fracture-cavity structure in the artificial rock core is incomplete, and the complex fracture-cavity structure is not completely consistent with the earlier design.
At this time, considering residual solid paraffin in the complex fracture-cavity structure, the karst cavity porosity of the fracture-cavity type carbonate rock artificial core
Crack porosity->
Quantitative calculation is carried out, and the calculation formula is as follows:
V r ＝V-V w ；
wherein V is the total volume of the fracture-cavity type carbonate rock artificial core; v (V) r The effective volume of the artificial rock core of the fracture-cavity type carbonate rock; v (V) cr Is an effective body for making holesAccumulating; v (V) fr Is the effective volume of the seam; v (V) w Is the volume of the injection well.
The porosity parameters of the artificial rock core of the fracture-cavity type carbonate rock of the comparative example are shown in table 7.
TABLE 7
The comparative example shows that a large amount of paraffin remains in the artificial rock core of the fracture-cave type carbonate rock, so that the volume of the karst cave and the volume of the fracture are far smaller than those of the example 1, and the porosity of the karst cave and the porosity of the fracture are correspondingly reduced, which is not in accordance with the earlier design.
(2) Nuclear magnetic detection method
After the artificial rock core is solidified and cooled to room temperature, the rock core mould is disassembled, and a large-aperture nuclear magnetic resonance imaging analyzer is used for scanning a representative area of the artificial rock core to obtain the T-shaped artificial rock core of the prepared fracture-cavity carbonate rock 2 A spectrogram.
FIG. 14 is a low field NMR T of representative region of the artificial carbonate core of the fracture-cavity type of this comparative example 2 A spectrogram; from fig. 14, it can be derived that: t (T) 2 The spectrogram curve is in bimodal distribution, the small peak represents the core matrix, the large peak represents the fracture-cavity structure, the relaxation time and peak area corresponding to the large peak are larger than those of the small peak, but the peak values of the two peaks are smaller than those of the embodiment 1, which shows that the fracture-cavity structure exists in the artificial core, but paraffin residues influence the fracture-cavity structure, so that the karst cavity volume and the fracture volume are far smaller than those of the embodiment 1.
FIG. 15 is a low field MRI of a representative region of a fracture-cave carbonate artificial core of the present comparative example; from fig. 15, it can be derived that: the middle area of the artificial rock core has an irregular karst cave structure, and the crack structure at the center axis of the whole rock core is not clear, which indicates that the artificial rock core has incomplete crack, karst cave and other space structures, and solid paraffin residues can influence the crack structure in the artificial rock core, so that the karst cave volume and the crack volume are far smaller than those of the embodiment 1.
Step eight: artificial core casting
And uniformly pouring the whole artificial rock core by using a casting material outside the rock core, wherein the pouring thickness is 20mm, and performing molding treatment at 25 ℃ for 60 hours to form the pouring fracture-cavity type carbonate rock artificial rock core with the compressive strength of 3 MPa.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a plurality of simple variants of the technical proposal of the invention can be carried out, comprising that each specific technical feature is combined in any suitable way, and in order to avoid unnecessary repetition, the invention does not need to be additionally described for various possible combinations. Such simple variations and combinations are likewise to be regarded as being within the scope of the present disclosure.
Claims (25)
1. A method for the non-destructive preparation of an artificial core having a fracture-cavity/fracture structure, the artificial core comprising fracture-cavity carbonate and/or fracture-type tight sandstone, the method comprising:
(1) Filling a first rock-forming mixture into a core mold;
(2) The ellipsoidal capsule and/or strip corresponding to the karst cave and/or crack structure of the actual hydrocarbon reservoir are pressed into the first rock-forming mixture, and after an injection well is arranged, pressing treatment is carried out;
(3) Taking out the ellipsoidal capsule body and/or the strip-shaped body to form a slot hole/crack structure;
(4) Filling 2-camphene powder into the fracture-cavity/crack structure, and filling a second rock-forming mixture into the core die;
(5) And (3) pressing, solidifying, detecting and pouring the diagenetic mixture to obtain the artificial core with the fracture-cavity/crack structure.
2. The method of claim 1, wherein the first and second diagenetic mixtures are the same, each comprising diagenetic mineral powder and/or cement.
3. The method of claim 2, wherein the diagenetic mineral powder is selected from carbonate minerals and/or non-carbonate minerals.
4. The method of claim 2, wherein the cement comprises bisphenol a epoxy resin, a curing agent, and a diluent.
5. The method of claim 4, wherein the bisphenol a epoxy resin is present in an amount of 65-87wt%, the curing agent is present in an amount of 10-25wt%, and the diluent is present in an amount of 3-10wt%, based on the total weight of the cement.
6. The method of claim 2, wherein the diagenetic mineral powder is present in an amount of 75-85wt% and the cement is present in an amount of 15-25wt%, based on the weight of the first diagenetic mixture or the second diagenetic mixture.
7. The method of claim 1, wherein the first rock-forming mixture is present in an amount of 30-70vol% and the second rock-forming mixture is present in an amount of 30-70vol%, based on the total volume of the core mold.
8. The method of claim 1, wherein the ellipsoidal capsule body comprises a central portion and end portions connected to the central portion, wherein the central portion is a cylinder and the end portions are hemispheres.
9. The method of claim 8, wherein the radius of the hemisphere is 15-20mm.
10. The method of claim 1, wherein the radius of the bar is 1-2mm.
11. The method of claim 1, wherein the injection well has an inner radius of 1-4mm and an outer radius of 1.5-4.5mm.
12. The method of claim 1, wherein the ellipsoidal capsule body, the strip body, and the injection well are all metallic.
13. The method according to claim 1, wherein in step (2), the conditions of the press treatment include: the temperature is 20-45 ℃, the pressure is 5-30MPa, and the time is 0.5-2.5h.
14. The method according to claim 1, wherein in step (5), the conditions of the press treatment include: the temperature is 20-45 ℃, the pressure is 5-30MPa, and the time is 0.5-2.5h.
15. The method of claim 1, wherein in step (5), the 2-camphor powder sublimates after the curing treatment, and a complex fracture hole/crack structure corresponding to a karst hole and/or crack structure of an actual hydrocarbon reservoir is formed inside the artificial core.
16. The method of claim 1 or 15, wherein the conditions of the curing process include: the temperature is 60-120 ℃ and the time is 24-60h.
17. The method of claim 1, wherein in step (5), the method of detection comprises a mass difference detection method and/or a nuclear magnetic detection method.
18. The method of claim 17, wherein the quality difference detection method comprises equation (a), equation (b), equation (c), and equation (d):
N＝(m 1 -m 2 )/m 0 formula (a);
wherein in formula (a), m 0 2-borneol powder mass for filling complex fracture-cavity/crack structure; m is m 1 The total mass of the artificial core with the fracture-hole/fracture structure before curing treatment; m is m 2 For the purpose of curing treatmentThe total mass of the artificial core with the fracture-hole/fracture structure;
V r ＝V-V w formula (b);
φ c ＝V c /V r x 100%, equation (c);
φ f ＝V f /V r x 100%, formula (d);
wherein in the formulas (b), (c) and (d), V is the total volume of the artificial core with the fracture-hole/fracture structure; v (V) r An effective volume of the artificial core with a fracture-hole/fracture structure; v (V) c Is the volume of an ellipsoidal capsule body for making holes; v (V) f The volume of the strip body for making the seam; v (V) w A volume for the injection well; phi (phi) c Is the karst cave porosity; phi (phi) f Is fracture porosity.
19. The method of claim 1, wherein in step (5), the casting process conditions include: the temperature is 20-45 ℃ and the time is 36-72h.
20. The method of claim 1, wherein the casting is performed with a casting material comprising an epoxy resin and a curing agent.
21. A method according to claim 1 or 20, wherein the casting is performed with casting material having a casting thickness of 20-30mm.
22. The method of claim 20, wherein the epoxy resin is present in an amount of 75-90wt% and the curing agent is present in an amount of 10-25wt%, based on the total weight of the casting material.
23. An artificial core having a fracture-hole/fracture structure prepared by the method of any one of claims 1-22.
24. The artificial core of claim 23, wherein the artificial core has a compressive strength of 2-5MPa.
25. The artificial core of claim 24, wherein the artificial core has a compressive strength of 3-4MPa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110805218.4A CN113484116B (en) | 2021-07-16 | 2021-07-16 | Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110805218.4A CN113484116B (en) | 2021-07-16 | 2021-07-16 | Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113484116A CN113484116A (en) | 2021-10-08 |
| CN113484116B true CN113484116B (en) | 2023-07-14 |
Family
ID=77939822
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110805218.4A Active CN113484116B (en) | 2021-07-16 | 2021-07-16 | Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113484116B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114330095B (en) * | 2021-11-20 | 2022-06-21 | 广西科学院 | Artificial granite intelligent manufacturing method based on LBM-DEM aggregate grading interface characteristic regulation and control |
| CN114199510B (en) * | 2021-12-06 | 2024-04-12 | 西南石油大学 | Integrated propping agent flat plate conveying experimental device and preparation method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2221168A1 (en) * | 1995-05-17 | 1996-11-21 | Nextec Applications, Inc. | Internally-coated porous webs with controlled positioning of modifiers therein |
| JPH11166071A (en) * | 1997-09-30 | 1999-06-22 | Inoac Corporation:Kk | Microporous material and its production |
| CN103822865A (en) * | 2014-03-20 | 2014-05-28 | 中国石油大学(华东) | High-resolution three-dimensional digital rock core modeling method |
| WO2017161916A1 (en) * | 2016-03-22 | 2017-09-28 | 西南石油大学 | Direct manufacturing method for large-scale, fractured-core model preserving original oil and water saturations |
| CN109357921A (en) * | 2018-10-10 | 2019-02-19 | 成都理工大学 | A kind of fracture hole oil reservoir Artificial Core Making method that parameter is controllable |
-
2021
- 2021-07-16 CN CN202110805218.4A patent/CN113484116B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2221168A1 (en) * | 1995-05-17 | 1996-11-21 | Nextec Applications, Inc. | Internally-coated porous webs with controlled positioning of modifiers therein |
| JPH11166071A (en) * | 1997-09-30 | 1999-06-22 | Inoac Corporation:Kk | Microporous material and its production |
| CN103822865A (en) * | 2014-03-20 | 2014-05-28 | 中国石油大学(华东) | High-resolution three-dimensional digital rock core modeling method |
| WO2017161916A1 (en) * | 2016-03-22 | 2017-09-28 | 西南石油大学 | Direct manufacturing method for large-scale, fractured-core model preserving original oil and water saturations |
| CN109357921A (en) * | 2018-10-10 | 2019-02-19 | 成都理工大学 | A kind of fracture hole oil reservoir Artificial Core Making method that parameter is controllable |
Non-Patent Citations (2)
| Title |
|---|
| Spontaneous imbibition investigation of self-dispersing silica nanofluids for enhanced oil recovery in low-permeability cores;Dai Caili etc.;Energy & Fuels;全文 * |
| 利用化学方法进行岩心制备的几点认识;孙天一等;当代化工;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113484116A (en) | 2021-10-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113484116B (en) | Method for preparing artificial rock core with fracture-cavity/fracture structure in nondestructive mode and artificial rock core | |
| Engelder et al. | The sliding characteristics of sandstone on quartz fault-gouge | |
| CN102053026B (en) | Material and method for manufacturing carbonate cave oil reservoir physical model | |
| CN103868772B (en) | A kind of synthetic core preparation method for rock drillability test | |
| CN104007463B (en) | A kind of artificial shale physical model and preparation method thereof and application | |
| US4932239A (en) | Standard target for explosive charge testing | |
| CN103926122B (en) | To shake out rock core and making apparatus thereof and method for making | |
| CN103048178A (en) | Method for preparing artificial rock core of simulated carbonate rock for acoustics experiment | |
| CN105651570A (en) | Preparation method of columnar jointed rock mass sample containing unfilled blind joints | |
| CN108225859A (en) | A kind of method that Single Fracture rock sample is prepared based on 3D printing technique | |
| AU2020103924A4 (en) | Artificial core preparation method for rock drillability test | |
| Christopher et al. | Laboratory testing of chemically grouted sand | |
| DE112017007119T5 (en) | TARGET COMPONENT CORE DEVICE FOR RADIAL FLOW GEOMETRY | |
| CN110108529A (en) | A kind of rocks-concrete assembly preparation method of sample | |
| CN106827170B (en) | A kind of fracture-cavity type carbonate artificial rock core and its 3D printing method | |
| CN108717005B (en) | A kind of preparation method of artificial viscous crude sandstone | |
| CN109342138A (en) | The artificial shale core production method of densification and its molding die for having stratification | |
| Shakor et al. | Investigation into the effect of delays between printed layers on the mechanical strength of inkjet 3DP mortar | |
| CN108414304A (en) | A kind of mold and method made for coupled shear-flow test joint samples | |
| Song et al. | In-situ X-CT scanning and numerical modeling on the mechanical behavior of the 3D printing rock | |
| CN203965204U (en) | The making apparatus of rock core shakes out | |
| CN108801739B (en) | Method for manufacturing artificial physical rock core | |
| Deng et al. | Experimental study on grouting effect and mechanical properties of the rockfill materials grouted with SCM | |
| CN109443886A (en) | A kind of simulation core production method for determining pore throat and particle surface properties | |
| US6238595B1 (en) | Target for testing perforating systems |
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 |