CN104819990A - Microscopic displacement experimental system and microscopic displacement experimental method based on CT digital core - Google Patents

Abstract

A microscopic displacement experiment system based on CT digital rock core, including a core holder and a microscopic displacement device; the core holder includes an inlet end, an outlet end, a core area, and a casing; the casing is polyether ether Ketone material PEEK; the microscopic displacement equipment, including parallel oil phase intermediate container and water phase intermediate container, advection pump for displacing oil phase intermediate container and water phase intermediate container, said oil phase intermediate container and water phase The liquid outlet ends of the intermediate containers are all connected to the inlet end of the core holder, and the core holder realizes pressurization of the core held therein through a hand pump, and at the outlet end of the core holder Set with metering bottle. The system of the invention is suitable for small-capacity and small-scale microscopic displacement experiments, and the technical equipment contained in it is higher in operating precision and measurement precision than traditional displacement experimental equipment.

Description

A microscopic displacement experiment system and microscopic displacement experiment method based on CT digital core

technical field

The invention relates to a CT digital rock core-based microscopic displacement experiment system and a microscopic displacement experiment method, belonging to the technical field of physical experiments of oil and gas.

Background technique

The ultimate goal of oil field development is how to extract as much crude oil as possible from formation pores to reduce waste of resources. Crude oil exists in the pores of sedimentary rocks thousands of meters underground. Due to the complexity of the depositional environment and fluid distribution in the formation, people have no way to directly understand the distribution of oil and water underground in a large scale. How to understand the enrichment area and enrichment form of underground crude oil, and how to determine the distribution of remaining oil in the reservoir are the main problems in oil field development, and also a major issue that has not been completely resolved in the upstream oil industry. Study the distribution of remaining oil from the micro and small-scale micro-nano level, understand and master the microcosmic formation mechanism and distribution law of remaining oil, intuitively reproduce the status quo of reservoir development, and carry out enhanced oil recovery research on this basis, which is the key to reservoir management important basis for decision-making. Therefore, microscopic displacement experiments and the study of the spatial distribution of fluids in cores after displacement have attracted the attention of major oil-producing countries at home and abroad.

There are mainly two methods commonly used in the study of fluid distribution in porous media: microscopic physical simulation and computer numerical simulation. Computer numerical simulation is to study the physical properties of reservoirs and the flow and distribution of fluids by establishing mathematical models. Although this method is widely used, there are still obvious uncertainties; microscopic physical simulation is to study the microscopic seepage process of reservoir fluid with the help of microscope magnification, video and image processing technology, so as to reveal the microscopic distribution characteristics of fluid in porous media . At present, the microscopic physical simulation is mainly based on the simulation model and two-dimensional view, but the simulation model cannot completely simulate all the characteristics of the core, and the fluid is always distributed in three-dimensional form in the rock pores. It is easy to observe from a two-dimensional perspective lead to large errors.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a microscopic displacement experiment system based on CT digital rock core.

The present invention also provides a method for performing microscopic displacement experiments using the above-mentioned experimental system. The present invention effectively combines conventional displacement experiments with CT technology, uses CT scanning technology to scan rock cores in different displacement stages, thereby observing the core pore structure, and can reproduce the change of fluid distribution in the pores in real time.

Technical scheme of the present invention is as follows:

A micro-displacement experimental system based on CT digital core, including a core holder and micro-displacement equipment;

The core holder includes an inlet port, an outlet port, a core area, and a shell; the shell is made of polyether ether ketone (PEEK), and PEEK is a special engineering plastic with excellent performance, which is resistant to high temperature (260°C), Excellent mechanical properties, radiation resistance, good self-lubrication, chemical corrosion resistance, etc.; compared with metals, PEEK material has ray transmission, and the holder shell made of it will not affect the normal use of CT equipment X-rays; existing The shell of the traditional gripper is made of metal material, X-rays cannot penetrate, so it is impossible to use CT equipment to scan to obtain the information of the core displacement state, and the size of the traditional gripper is too large, which does not match the size of the CT scanning sample, which affects the scanning effect;

The microscopic displacement equipment includes a parallel oil phase intermediate container and a water phase intermediate container, an advection pump for displacing the oil phase intermediate container and the water phase intermediate container, the outlet of the oil phase intermediate container and the water phase intermediate container The liquid ends are all connected to the inlet end of the core holder, and the core holder pressurizes the core held therein through a hand pump, and a metering bottle is arranged at the outlet end of the core holder .

Preferably, according to the present invention, a rotating seat is provided at the bottom of the core holder. The rotating seat is used to fix the core holder on the CT sample stage during the CT scanning process, and remove it during the displacement experiment so that the core holder can be connected to the displacement process.

Preferably, according to the present invention, the capacities of the oil phase intermediate container and the water phase intermediate container are both 50-150 mL.

Preferably according to the present invention, a pressure gauge is provided on the pipeline between the hand pump and the core holder, and the range of the pressure gauge is 10MPa, and the accuracy is 0.25MPa.

Preferably, according to the present invention, an inlet pressure gauge is provided at the inlet end of the core holder, the range of the inlet pressure gauge is 6 MPa, and the accuracy is 0.25 MPa.

Utilize above-mentioned experiment system to carry out the method for microcosmic displacement experiment, comprise steps as follows:

1) dry the core and install it in the core holder, place it in the Zeiss MCT-400 CT for positioning, scan the core, and obtain the three-dimensional digital core data volume in the core analysis area;

2) Connect the core holder to the micro-displacement equipment, and realize single-phase water phase displacement, single-phase oil phase displacement or multi-phase mixed displacement experiment of water phase and oil phase on the core;

3) According to the research content of the displacement experiment, the observation time point is designed, which is the displacement time, and the displacement of the core is suspended at the observation time, and the outlet port, the inlet port and the hand pump of the core holder are closed;

4) put the core holder into the Zeiss MCT-400 CT to scan, and obtain the fluid distribution in the core at the moment of displacement;

5) Step 2) to step 4) are repeated until the fluid distribution in the core is obtained at all designed observation time points according to step 3).

Preferably according to the present invention, the diameter of the rock core in step 1) is 1-2 cm, and the length is 2-4 cm.

The advantages of the present invention are:

1. The present invention uses on-site rock cores to restore the pore structure of the oil reservoir to the greatest extent, simulate the fluid flow conditions of the oil reservoir, and ensure the reliability of the experiment. At the same time, the rock sample with a diameter of 1-2 cm is easier to obtain accurate CT scanning results than the standard rock sample with a diameter of 2.5 cm.

2. The experimental method of the present invention can not only obtain data through experiments, but also can perform visual analysis on the fluid distribution in the rock core under different displacement stages.

3. The system and method of the present invention can not only obtain the three-dimensional distribution of the fluid in the porous medium, but also ensure the accuracy of the measured fluid distribution result, which is more in line with the actual situation than the two-dimensional one.

4. The invention guarantees the implementation of various displacement indoor experiments in the petroleum industry, and can simulate various displacement methods and displacement conditions.

5. The system of the present invention is suitable for small-capacity and small-scale microscopic displacement experiments, and the technical equipment contained in it is higher in operation accuracy and measurement accuracy than traditional displacement experimental equipment.

Description of drawings

Fig. 1 is a structural connection diagram of the displacement system of the present invention;

In Fig. 1, 1, advection pump; 2, intermediate container of oil phase; 3, intermediate container of water phase; 4, core holder; 4-1, inlet port; 4-2, outlet port; 5, hand pump ; 6. The pressure gauge set between the core holder and the hand pump; 7. The metering bottle.

Fig. 2 is a fluid distribution diagram in a digital core at a certain moment scanned by the displacement experiment method of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the embodiments and the accompanying drawings, but is not limited thereto.

As shown in Figure 1 and Figure 2.

Embodiment 1,

A micro-displacement experimental system based on CT digital core, including a core holder and micro-displacement equipment;

The core holder 4 includes an inlet port 4-1, an outlet port 4-2, a core area, and a shell; the shell is made of polyether ether ketone (PEEK);

The microscopic displacement equipment includes a parallel oil phase intermediate container 2 and a water phase intermediate container 3, an advection pump 1 for displacing the oil phase intermediate container 2 and the water phase intermediate container 3, the oil phase intermediate container 2 and the water phase intermediate container 3 The liquid outlet ends of the water-phase intermediate container 3 are all connected to the inlet port 4-1 of the core holder 4, and the core holder 4 pressurizes the rock core held therein through the hand pump 5. The outlet end 4-2 of the core holder 4 is provided with a metering bottle 7 .

Embodiment 2,

A microscopic displacement experiment system based on CT digital core as described in Example 1, the difference is that a rotating seat is provided at the bottom of the core holder 4 . The rotating seat is used to fix the core holder on the CT sample stage during the CT scanning process, and remove it during the displacement experiment so that the core holder can be connected to the displacement process.

Embodiment 3,

A microscopic displacement experiment system based on CT digital core as described in Example 1, the difference is that the capacities of the oil phase intermediate container 2 and the water phase intermediate container 3 are both 50-150 mL.

A pressure gauge 6 is arranged on the pipeline between the hand pump 5 and the core holder 4, the range of the pressure gauge 6 is 10MPa, and the accuracy is 0.25MPa.

An inlet pressure gauge is provided at the inlet end 4-1 of the core holder 4, the range of the inlet pressure gauge is 6MPa, and the precision is 0.25MPa.

Embodiment 4,

Utilize the method for microcosmic displacement experiment as described in any one of embodiment 1-3 experimental system, comprise steps as follows:

1) dry the rock core and install it in the rock core holder 4, place it in Zeiss MCT-400 CT for positioning, scan the rock core, and obtain the three-dimensional digital rock core data volume in the core analysis area;

2) Connecting the core holder 4 to the micro-displacement equipment, and performing single-phase water displacement, single-phase oil phase displacement or multi-phase mixed displacement experiments of water phase and oil phase on the core;

3) According to the research content of the displacement experiment, the observation time point is designed, which is the displacement time. At the observation time, the displacement of the core is suspended, and the outlet port 4-2, the inlet port 4-1, and the core holder are closed. hand pump 5;

4) Put the core holder 4 into the Zeiss MCT-400 CT for scanning, and obtain the fluid distribution in the core during the displacement moment;

5) Step 2) to step 4) are repeated until the fluid distribution in the core is obtained at all designed observation time points according to step 3).

The rock core in the step 1) has a diameter of 1-2 cm and a length of 2-4 cm.

As shown in Fig. 2, the fluid distribution in the core can be monitored in real time by using CT scanning.

Claims (7)

1. based on a microscopic displacement experiment system for CT digital cores, it is characterized in that, this system comprises core holding unit and microcosmic displacement equipment;

Described core holding unit, comprises entrance point, endpiece, rock core district, shell; Described shell is polyetheretherketonematerials materials, described microcosmic displacement equipment, comprise oil phase intermediate receptacle in parallel and aqueous phase intermediate receptacle, constant-flux pump for displacement oil phase intermediate receptacle and aqueous phase intermediate receptacle, described oil phase intermediate receptacle is all connected with the entrance point of described core holding unit with the outlet end of aqueous phase intermediate receptacle, described core holding unit realizes pressurizeing to the rock core wherein clamped by wobble pump, and the endpiece of described core holding unit is provided with recorder jar.

2. a kind of microscopic displacement experiment system based on CT digital cores according to claim 1, is characterized in that, bottom described core holding unit, be provided with rotation seat.

3. a kind of microscopic displacement experiment system based on CT digital cores according to claim 1, it is characterized in that, the capacity of described oil phase intermediate receptacle and aqueous phase intermediate receptacle is 50-150mL.

4. a kind of microscopic displacement experiment system based on CT digital cores according to claim 1, it is characterized in that, the pipeline between described wobble pump and core holding unit is provided with tensimeter, described manometric range is 10MPa, precision 0.25MPa.

5. a kind of microscopic displacement experiment system based on CT digital cores according to claim 1, is characterized in that, the entrance point of described core holding unit is provided with inlet pressure gauge, and the range of described inlet pressure gauge is 6MPa, precision 0.25MPa.

6. utilize experimental system as described in claim 1-5 any one to carry out the method for microscopic displacement experiment, it is characterized in that, it is as follows that the method comprising the steps of:

1) be arranged on after rock core drying in described core holding unit, be placed in Zeiss MCT-400 CT and locate, scanning rock core, obtain core analysis area three-dimensional digital cores data volume;

2) core holding unit is accessed microcosmic displacement equipment, single-phase aqueous phase displacement, single-phase oil phase displacement or aqueous phase, the heterogeneous mixing displacement test of oil phase are realized to described rock core;

3) according to the research contents design observation moment point of displacement test, be the displacement moment, suspend described rock core displacement in the described observation moment, close outlet port of rock core holder, entrance point, wobble pump;

4) core holding unit is put into Zeiss MCT-400 CT to scan, when obtaining this displacement moment, the fluid distrbution in described rock core;

5) step 2 is repeated) to step 4), until according to described step 3) all design observation moment point obtain fluid distrbution in described rock core.

7. experimental technique as claimed in claim 6, is characterized in that, described step 1) in the diameter of rock core be 1-2cm, length is 2-4cm.