CN106596223A - Production method of rock core for compact gravel rock oil displacement - Google Patents

Abstract

The invention discloses a method for preparing a dense sandy conglomerate core for oil displacement. The method comprises the following steps: mixing quartz sand with a certain particle size, clay mineral and cement powder in proportion; assembling a mold; wetting the mold: filling the mold Before sanding, spray 3mg of water into the destination layer on the lower surface of the sand body that is about to be in contact with the sand body with a fine water spray head, and sand homogenization: weigh the quartz sand mixture of 1/N mold volume into the mold, and use a scraping tool Move back and forth in the horizontal direction, and finally press it with a briquetting block; stabilize the pressure of the filled mold for 15 minutes and then release the pressure; repeat steps (3) to (5) until the mold is full, and put the core mold as a whole in a constant temperature box for drying Bake; unmould. The invention prepares a large-volume tight core, which has the advantage of small dead pores, and optimizes the blank of tight sandstone in laboratory experiments that only rely on coring experiments without artificial cores, providing assistance for the development of unconventional oil and gas fields.

Description

A kind of core preparation method for oil displacement of tight sandy conglomerate

technical field

The invention relates to a method for preparing a dense sandy conglomerate core for oil displacement, and belongs to the technical field of artificial core and its preparation.

Background technique

The energy exploration reserves of unconventional oil and gas reservoirs (tight sandstone) are huge, which has attracted widespread attention, and its development has also become the main research field of the current topic. Due to the uniqueness of its reservoirs, conventional means cannot produce and develop effectively and efficiently. A reasonable development plan is the basis of oil and gas field development, and necessary/accurate laboratory is the basis of the foundation. Therefore, the basis for laboratory experimental research- Core making to simulate reservoirs is critical.

At present, there are countless studies on core making, but most of them are based on the core making of conventional oil and gas reservoirs. For example, Professor Pi Yanfu described various types of Core production is mainly based on the geological conditions of conventional oil reservoirs in Daqing Oilfield.

For the design of tight sandstone, only Wu Songtao, a temperature-pressure double-controlled dense artificial sandstone core and its preparation method, the publication number is CN104931312A, he used a high temperature of 300 degrees and a high pressure of 220MPa to make the core, which can meet the required core porosity and permeability. Achieving the porosity and permeability required by the design is only the primary problem in making compact cores. The next important issue is the size of the cores to be produced. Using the above-mentioned production methods, it is not possible to form larger volumes of compact cores. If only the size with Under the condition of short core and bottom hole low permeability, the pore volume is very limited (for example, the pore volume of a 10cm long core is only a few ml), so for the oil displacement experiment, the experimental error of recovery factor/water cut can be directly Affect the conclusion; the injection pressure still shows an increase under the condition of complete water flooding. The three important parameters that mainly characterize the oil displacement effect/displacement characteristics cannot be effectively displayed at all.

Therefore, it is necessary to design a more ideal model and production method for tight sandstone cores for oil displacement.

Contents of the invention

In order to solve the technical problems in the prior art, the present invention provides a core preparation method for tight glutenite oil displacement. The method is mainly to manufacture artificial cores for laboratory experiments to study the displacement characteristics of tight glutenite reservoirs, which can meet the requirements of laboratory experiments. Indoor displacement experimental study on tight sandstone reservoir types.

The technical scheme adopted by the present invention to solve the above-mentioned technical problems is: a kind of dense sandy conglomerate oil displacement core preparation method, the method comprises the following steps:

(1) batching: the quartz sand of certain particle size, clay mineral and cementing agent powder are mixed in proportion, stir evenly, obtain the quartz sand mixture;

(2) Assembled mold: The mold is mainly composed of bottom plate, side plate, and briquetting block, among which the bottom plate, side plate, and briquetting block are all steel plates, and the surface roughness of the inner wall is Ra≤0.025μm. The geometric dimensions of the square core mold: length×width×height =305mm×92mm×92mm;

(3) Mold wetting: Before filling the mold with sand, spray 3mg of destination layer water into the lower surface of the sand body that is about to be in contact with the fine water spray head, and cover it evenly;

(4) Sand homogenization: Weigh the quartz sand mixture of 1/N mold volume into the wet mold, use a scraping tool to move back and forth in the mold in the horizontal direction until the surface of the quartz sand mixture is flat, and finally use a briquetting block to The quartz sand mixture is pressed;

(5) Compaction: Place the filled mold on a predetermined four-column hydraulic press, pre-press for 5 minutes under the condition of a pressing pressure of 80 MPa, then control the press to stabilize the pressure at 80 MPa, and release the pressure after stabilizing for 15 minutes;

(6) Repeat steps (3) to (5) until the mold is full, wherein when step (5) is repeated once more, the pressure of step (5) increases by 10MPa;

(7) Molding: put the core mold with the briquette into the constant temperature box, and bake it under variable temperature and timing conditions. The baking temperature and time are 100°C, 240min→130°C, 30min→210°C, 10min→natural cool down;

(8) Demoulding: place the formed rock core mold on a fixed position of a four-column hydraulic press, and press the briquetting to make the rock core escape from the mold to obtain a rock core.

Further, the cementing agent in the step (1) is mainly composed of the following components in mass percentage: curing agent 9-20%, leveling agent 1-5%, barium sulfate 0.5-1%, and the balance is ring Oxygen resin and polyester, wherein the mass percentage of epoxy resin and polyester is 1:1.

Further, the corresponding relationship between the particle size content of the cement in the step (1) is consistent with the particle size ratio of the quartz sand.

Further, in the step (2), a high temperature resistant film is placed between the bottom plate and the side plate of the mould.

Further, in the step (4), after the quartz sand mixture is loaded into the mold, a sand homogenizer is used to remove the bridge plug of the quartz sand mixture, so that the quartz sand mixture forms close point contact with each other.

Further, in the step (5), during the process of compacting the quartz sand mixture, 90HZ-150HZ ultrasonic waves can be simultaneously released to the mold containing the quartz sand.

Beneficial effects of the present invention: the present invention has prepared a large-volume compact rock core, which has the advantage of small dead pores, and optimizes the blank of tight sandstone in laboratory experiments that only rely on coring experiments without artificial cores, which is very Assist in the development of standard oil and gas fields.

detailed description

The specific implementation of the present invention will be further described below in conjunction with the examples, and the present invention is not limited to the scope of the examples.

A kind of tight sandy conglomerate oil displacement core preparation method of the present invention, the method comprises the following steps:

(1) Ingredients: Mix quartz sand, clay minerals and cement powder of a certain particle size in proportion, and stir evenly to obtain a quartz sand mixture; according to the characteristics of the oil reservoir, screen the required size of quartz sand with filters of different meshes Particles, combined with powder cement (particle size distribution is 75 μm ~ 100 μm), clay minerals are weighed according to the lithological mineral content of sandstone reservoirs;

The cementing agent is mainly composed of the following components by mass percentage: curing agent 9-20%, leveling agent 1-5%, barium sulfate 0.5-1%, and the balance is epoxy resin and polyester, of which epoxy resin and The mass percentage of polyester is 1:1. The mass ratio of quartz sand to cement is 5-12.5:1.

The particle size content correspondence of the cement is consistent with the particle size ratio of the quartz sand (for example, sand body 20 mesh: 120 mesh = 5: 1 = cement 80 mesh: 180 mesh), because the bonding agent under this condition / The consolidation ability is strong, because some sand body particles of quartz sand are large in size, the conventional adhesive may not be able to stick to the sand particles, and the appropriate particle size ratio can be more reasonably matched and contacted, and all too fine will lead to increased dead pores.

(2) Assembled mold: The mold is mainly composed of bottom plate, side plate, and briquetting block, among which the bottom plate, side plate, and briquetting block are all steel plates, and the surface roughness of the inner wall is Ra≤0.025μm. The geometric dimensions of the square core mold: length×width×height ＝305mm×92mm×92mm; the bottom plate and the side plate of the mold are cushioned with a high temperature resistant film, the purpose of which is to avoid damage to the bottom of the core during the demoulding process;

The side plate in the above-mentioned mold is an integral ring wall, which has integrity. The side plate, bottom plate and briquetting block are all roughened on the surface to promote the fit between the core particles and the mold; and the pressing surface of the briquetting block has vent holes to avoid filling During the compression process, the produced gas in the core cavity impacts the core particles and cemented particles, changing the contact relationship of the particles after uniform mixing.

(3) Mold wetting: Before filling the mold with sand, spray 3mg of destination layer water on the lower surface of the sand body that is about to be contacted with a fine water spray head, and cover it evenly; the purpose is to absorb the quartz sand mixture that is about to be filled, Reduce the contact between the cement on the upper surface and the compact, and finally avoid a large amount of accumulation on the contact surface to form dead pores;

(4) Smooth sand: Weigh the quartz sand mixture of 1/N mold volume and put it into the wet mold, remove the bridge plug of the quartz sand mixture with a sand homogenizer, so that the quartz sand mixture forms close point contact with each other, and then Use a scraping tool to move back and forth horizontally in the mold until the surface of the quartz sand mixture is flat, and finally press the quartz sand mixture with a pressing block;

(5) Compaction: Place the filled mold on a predetermined four-column hydraulic press, pre-press for 5 minutes under the condition of a pressing pressure of 80 MPa, control the press again to stabilize the pressure at 80 MPa, and release the pressure after 15 minutes of stabilizing; after compacting During the process of quartz sand mixture, 90HZ~150HZ ultrasonic waves can be released to the mold with quartz sand at the same time. Under high pressure, ultrasonic waves of this wavelength can effectively promote the vertical migration between particles and force the contact to be closer;

(6) Repeat steps (3) to (5) until the mold is full, wherein the pressure in step (5) increases by 10 MPa each time step (5) is repeated, and the briquette is integrated into the high-temperature oven on the mold - the pressure The gradient pressurization under certain conditions is the result of multiple rounds of experiments, in order to maintain vertical consistency; in this way, the cement attached to the surface of the briquette after multiple fillings will also be on the surface of the uppermost core, so that the cementation of each layer The agent is relatively uniform and uniform vertically;

(7) Molding: put the core mold with the briquette into the constant temperature box, and bake it under variable temperature and timing conditions. The baking temperature and time are 100°C, 240min→130°C, 30min→210°C, 10min→natural cool down;

(8) Demoulding: Place the formed core mold on a fixed position of a four-column hydraulic press, press the briquette to release the core from the mold to obtain a core, and the obtained core is an artificial core with a size of less than 305mm×92mm×92mm, which is cut with liquid nitrogen The core was further modified by the machine to fix its size to 300mm×89mm×89mm.

The above method prepares a compact core with a frame size of 300mm×89mm×89mm, which has the advantages of large volume and small dead pores, and optimizes the blank of tight sandstone in the laboratory experiment that only relies on coring experiments without artificial cores. , to provide assistance for the development of unconventional oil and gas fields.

Claims (6)

1. a kind of tight sandy conglomerate flooding oil core preparation method is characterized in that, the method may further comprise the steps: (1) batching: the quartz sand of certain particle size, clay mineral and cementing agent powder are mixed in proportion, stir evenly, obtain the quartz sand mixture; (2) Assembled mold: The mold is mainly composed of bottom plate, side plate, and briquetting block, among which the bottom plate, side plate, and briquetting block are all steel plates, and the surface roughness of the inner wall is Ra≤0.025μm. The geometric dimensions of the square core mold: length×width×height =305mm×92mm×92mm; (3) Mold wetting: Before filling the mold with sand, spray 3mg of destination layer water into the lower surface of the sand body that is about to be in contact with the fine water spray head, and cover it evenly; (4) Sand homogenization: Weigh the quartz sand mixture of 1/N mold volume into the wet mold, use a scraping tool to move back and forth in the mold in the horizontal direction until the surface of the quartz sand mixture is flat, and finally use a briquetting block to The quartz sand mixture is pressed; (5) Compaction: Place the filled mold on a predetermined four-column hydraulic press, pre-press for 5 minutes under the condition of a pressing pressure of 80 MPa, then control the press to stabilize the pressure at 80 MPa, and release the pressure after stabilizing for 15 minutes; (6) Repeat steps (3) to (5) until the mold is full, wherein when step (5) is repeated once more, the pressure of step (5) increases by 10MPa; (7) Molding: put the core mold with the briquette into the constant temperature box, and bake it under variable temperature and timing conditions. The baking temperature and time are 100°C, 240min→130°C, 30min→210°C, 10min→natural cool down; (8) Demoulding: place the formed rock core mold on a fixed position of a four-column hydraulic press, and press the briquetting to make the rock core escape from the mold to obtain a rock core. 2. a kind of tight sandy conglomerate oil flooding core preparation method according to claim 1, is characterized in that, the cementing agent in the described step (1) is mainly made up of the component of following mass percent: curing agent 9～20 %, leveling agent 1-5%, barium sulfate 0.5-1%, and the balance is epoxy resin and polyester, wherein the mass percentage of epoxy resin and polyester is 1:1. 3. according to claim 1 and 2 described a kind of tight sandy conglomerate oil flooding core preparation method, it is characterized in that, in the described step (1), the particle diameter content corresponding relation of cementing agent is consistent with the particle diameter ratio of quartz sand . 4. a kind of tight sandy conglomerate oil displacement core preparation method according to claim 3 is characterized in that, in described step (2), in the bottom plate of mold and side plate middle pad adds high temperature resistant film. 5. according to claim 1,2,4 described a kind of tight sandy conglomerate oil flooding core preparation method, it is characterized in that, after the quartz sand mixture is loaded into mold in described step (4), remove quartz sand with homogenizer The bridge plug of the mixture makes the quartz sand mixture form close point contact with each other. 6. a kind of tight sandy conglomerate oil flooding core preparation method according to claim 5 is characterized in that, in the process of compacting the quartz sand mixture in the described step (5), the mold that quartz sand is housed can be simultaneously Release 90HZ ~ 150HZ ultrasonic waves.