CN107387041A - One kind note critical medium oil shale single well stimulation conversion process - Google Patents

Abstract

A single-well huff and puff conversion process for injecting critical medium oil shale, which is to drill a working well to form a single-well model, and perforate at the position of the oil shale layer at the bottom of the well to improve the porosity and permeability of the oil shale, and to Water and gas are injected into the working well and heated to make the bottom of the well reach the predetermined critical environment. The organic matter in the oil shale is cracked through the extraction and catalysis of the critical medium. As the critical medium gradually penetrates into the oil shale, the oil shale is finally realized The shale is gradually extracted from the inside to the outside, and the obtained oil-water mixture is pumped to the surface for oil-water separation to obtain shale oil and shale gas. After the reaction is over, the separated critical medium is recirculated and injected to realize the secondary utilization of waste heat. The invention reduces mining cost and improves mining efficiency.

Description

A single-well huff and puff conversion process for oil shale with critical medium injection

technical field

The present invention relates to an oil shale mining process, in particular to a critical medium injection oil shale single well huff and puff conversion process. By injecting critical medium into a single well, the organic matter of oil shale is cracked into organic compounds with different chain lengths, thereby Obtain shale oil and shale gas to realize in-situ conversion of oil shale. It is a method that can increase the oil production rate of oil shale. This technical method can be widely used in in-situ mining of solid or condensed mineral fuels (oil shale, coal, heavy oil).

Background technique

Looking at the development of the international society and economy in the past, it can be found that oil plays a very important role in politics, military affairs, diplomacy, etc., and the competition in the oil field is becoming increasingly fierce. my country has become a net importer of oil since 1993, and its dependence on imported crude oil has gradually increased. In 2016, the apparent consumption of crude oil in the country was 577.8 million tons, and its dependence on foreign countries was as high as 65.4%, an increase compared to 2015. 4.6 percentage points. Therefore, the temporary shortage of supply or price fluctuations in the international oil market will affect the development of China's economy and threaten my country's energy security. Oil shale, as a kind of unconventional energy with huge reserves, has become an important research direction all over the world because of its abundant resources and mining feasibility.

Oil shale is a kind of sedimentary rock with high ash content containing combustible organic matter inside. When the temperature reaches a certain requirement, the internal organic matter undergoes cracking reaction and generates shale oil and organic gas. How to extract shale oil more efficiently and increase the production of shale oil and gas has become the key to in-situ cracking of oil shale.

At present, oil shale mining technologies are mainly divided into surface carbonization technology and in-situ mining technology. Although the surface dry distillation technology is relatively mature and widely used, it has many disadvantages: it produces highly polluted waste gas and sewage, accumulates a large amount of waste residue, occupies a large area, and pollutes the environment; the mining of underground oil shale is likely to cause goafs, resulting in The ground caved in. The oil shale in-situ mining technology can not only solve many problems of surface dry distillation, but also can be applied to the cracking of deep low-quality oil shale, which is a method with very broad development prospects. At present, many countries in the world have proposed the in-situ cracking method of oil shale. The CRUSH technology jointly developed by Chevron and the Los Alamos National Laboratory of the United States, the patent number is CN101421488A, its working principle is to inject high-temperature _CO2 into the fractured oil shale formation, which is beneficial to The oil shale layer is fractured, and the oil shale layer is heated through convective heat transfer, and the hydrocarbon gas produced is produced from the production well along with the fluid. IEP has developed the GFC technology, which uses the reaction heat of the high-temperature fuel cell stack to heat the oil shale in situ, and the hydrocarbon gas generated by heating can be used as fuel to pass into the cell stack, but it needs to be passed in when starting the device. Natural gas was used as the starting fuel. EGL company proposed the principle of convection and backflow heat transfer, through which the oil shale is heated in situ. The key to this technology is to set up a horizontal well heat exchange system, forming a closed loop, and the energy loss during the heating process is small , high energy utilization. An underground in-situ extraction method of hydrocarbons in oil shale proposed by Jilin University, through the use of multi-wells, using electromagnetic heating or supercritical steam generators to achieve a near-critical environment, thereby realizing the extraction of hydrocarbons. Taiyuan University of Technology has studied the group well fracturing convective heating method to heat oil shale in situ. The group well fracturing can connect the fractures between the group wells, introduce high-temperature gas for cracking, and simultaneously heat the wells and production wells. Carry out interval rotation to improve the heating uniformity of oil shale, and the oil production rate will increase accordingly. Israeli scientists and Jilin University jointly developed the local chemical reaction method (Topochemical in-situ method), referred to as the TS method. The TS method introduces air and hydrocarbon gases into the ground through convection, and burns to generate heat to heat the oil shale. The air content is passed to achieve the best heating effect and complete the in-situ cracking.

Contents of the invention

The purpose of the present invention is to provide a critical medium injection oil shale single well huff and puff conversion process. The present invention realizes the extraction of shale oil by injecting critical medium into the oil shale layer, which can effectively reduce construction time and construction cost. During the whole process, a critical environment is formed by controlling the temperature and pressure of the injection medium, and finally the conversion of in-situ oil shale is realized.

The present invention forms a single well mode by first drilling a working well, performs perforation at the position of the oil shale layer at the bottom of the well, improves the porosity and permeability of the oil shale, and injects water and gas into the working well and heats it so that the bottom of the well reaches In the predetermined critical environment, the organic matter in the oil shale is cracked through the extraction and catalysis of the critical medium, and the oil and water are separated after being extracted to the surface to obtain shale oil and shale gas. After the reaction is over, inject the separated critical medium into the working well to realize the secondary utilization of waste heat.

Concrete steps of the present invention are:

(1) According to the distribution characteristics of the oil shale layer, drill a well to the target oil shale layer and carry out well completion construction;

(2) Two pipelines are lowered into the well as gas injection and water injection pipelines and oil production pipelines, wherein gas injection and water injection share one pipeline to form gas injection and oil production channels;

(3) Put the critical medium heater into the working well along with the pipeline, and close the wellhead;

(4) Inject water and inert gas into the well, and the injection rate is determined according to the thickness of the oil shale layer;

(5) Turn on the critical medium heater to form a supercritical or near-critical environment with a temperature of 300°C-450°C and a pressure of 9-25MPa inside the oil shale, and keep the temperature and pressure in the rock formation for 48 hours;

(6) Under the action of the critical medium, the asphaltene and kerogen inside the oil shale are extracted by taking advantage of its advantages of high diffusion coefficient, high solubility and low viscosity, and an oil-water mixture is formed in the working well.

(7) Reduce the pressure of the working well, pump the extracted oil-water mixture to the surface through the oil production channel, use the oil-water separation equipment to separate the shale oil and water, and the separated water will be circulated and injected into the working well after being softened , for continued extraction of shale oil.

(8) After the oil shale extraction work in the area is completed, the separated water is injected into the working well, and the circulated hot water can be directly injected into the new working well to form the reuse of oil shale energy.

The beneficial effects of the present invention are:

The invention utilizes the very good solubility of the critical medium, which can be used not only as a solvent, but also as a reactant and catalyst to extract organic matter in oil shale in situ. In the process of extracting hydrocarbon products with critical medium, the critical medium firstly acts as a heat transfer medium to transfer heat to the oil shale layer, which accelerates the maturing and extraction of oil shale; at the same time, it acts as a catalyst to promote the rapid extraction of shale oil, and finally acts as a solvent to The extracted shale oil is carried to the surface. By changing the temperature and pressure, the environment of the reaction can be changed, and the rate of the reaction and the selective activity of the catalyst can be coordinated. At the same time, water is cheap, non-toxic, and easily separated from dissolved products, which saves costs for underground in-situ mining. Put the critical medium heater into the working well, and the energy generated is directly transferred to water or steam, reducing heat loss. In addition, the single well circulation process can effectively ensure the critical state of the underground and reduce the risk of pressure leakage, which is better than other underground dry distillation methods Short time and high efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the present invention.

Fig. 2 is a top view of the sealing cover.

In the figure: 1-oil shale layer; 2-working well; 3-critical medium heater; 4-packer; 5-packer channel; 6-gas injection and water injection pipeline; 7-backwater and oil production pipeline; 8-cable and signal line; 9-heater controller; 10-high pressure water pump; 11-supercharger; 12-stabilizing tank; 13-water storage tank; 14-oil-water separation equipment; 15-gas tank; 16-oil Jar; 17 airtight lids

detailed description

Example 1: As shown in Figure 1, the specific steps of this embodiment are as follows:

The buried depth of oil shale in a certain place is 410-420m, the thickness of oil shale in the target layer is 9m, the oil content is 5.73%, the ash content is 83%, the volatile matter content is 18.26%, and the calorific value is 3998.31J/g.

(1) Drilling and completion:

a. Determine the position of the working well according to the direction and horizon of the oil shale;

b. Drill a working well on the ground with a diameter of 346mm, and run a casing of 244.5mm at 0-422m. The end of the casing is run into floating hoops and floating shoes, and elastic centralizers are fixed every 20m outside the casing; casing and well Cementing with cement slurry between the walls;

c. Perform perforation at a hole depth of 409-422m to improve the permeability of oil shale around the working well;

(2) Equipment installation and preliminary work:

a. Connect critical medium heater 3 and packer 4 on the surface, and install oil-water separation equipment 14, heater controller 9, high-pressure water pump 10, supercharger 11, surge tank 12, water storage tank 13, and oil-water separation equipment on the ground 14. Gas tank 15, oil tank 16 and other corresponding facilities;

b. The critical medium heater 3 and the packer 4 are connected to the tubing 7 and cables and signal lines 8 to be lowered into the well successively. A total of 2 pipelines and 4 cables are lowered into the well. The wellhead is sealed with a flange. The 2 pipelines and the wellhead The flange is welded and sealed, the 4 cables and the wellhead flood are sealed with graphite pressure, the final position of the packer 4 is -395~409m, and the position of the critical medium heater 3 is 410~417m;

c. In the test, the gas injection pipeline 6 and the water injection pipeline 6 are common, the return pipeline 7 is used alone, and the packer 4 is used in the hole to seal the critical medium heating area and other casing parts;

d, seal the wellhead with a sealing cover 17;

e. Inject 0.5m3 water into the well, and turn on the critical medium heater 3, observe the pressure, temperature, and liquid level changes at the bottom of the hole, and replenish water in time when the liquid level drops; make the internal formation temperature of the oil shale 1 be 300°C-450°C , a supercritical or near-critical environment with a pressure of 9-25MPa, working continuously for 48 hours;

(3) Reaction stage:

a. Under the action of the critical medium, the asphaltene and kerogen inside the oil shale 1 are extracted by taking advantage of its advantages of high diffusion coefficient, high solubility and low viscosity, and an oil-water mixture is formed in the working well;

b. Real-time monitoring of the pressure and temperature in the working well. When the temperature or pressure is lower than the set target value, the real-time heater controller 9, the adjustment of the high-pressure water pump 10 and the supercharger 11 are required to ensure a higher extraction of oil shale efficiency;

(4) Post-processing stage:

a. Reduce the pressure of the working well, extract all the oil-water mixture produced by the extraction to the surface through the oil production channel 7, use the oil-water separation equipment 14 to separate the shale oil and water, and the separated water is softened and then injected into the In working wells, used to continue to extract shale oil;

b. Reset the temperature and pressure in the working well 2, turn on the downhole critical medium heater 3, and continue the test with a period of 48 hours;

c. After the extraction of oil shale 1 in the area is completed, water and steam are injected into the working well 2, and the circulated hot water can be directly injected into new working wells to form the repeated utilization of oil shale energy;

d. The shale oil and shale gas obtained after cooling and oil-water separation are stored in the oil storage tank 16 and the gas storage tank 15 respectively.

Claims (5)

1. one kind note critical medium oil shale single well stimulation conversion process, it is characterised in that：It is by subdrilling a bite active well shape Into individual well pattern, perforation is carried out in shaft bottom oil shale layer position, improves the porosity and permeability of oil shale, and into active well Injection water and gas simultaneously make shaft bottom reach predetermined critical environment using donwhole heater heating medium, pass through the extraction of critical medium Take and cracking of the catalytic action completion to organic matter in oil shale, as critical medium is gradually penetrated into inside oil shale, final reality The now progressively extraction to oil shale from inside to outside, the oil water mixture of acquisition is drawn into after earth's surface and carries out water-oil separating acquisition page Shale oil and shale gas.The secondary use to waste heat is realized in the critical medium circulation injection isolated.

A kind of 2. note critical medium oil shale single well stimulation conversion process according to claim 1, it is characterised in that：It is described Active well be individual well structure.

A kind of 3. note critical medium oil shale single well stimulation conversion process according to claim 1, it is characterised in that：It is described Medium for water, nitrogen or carbon dioxide or cracking after short-chain hydrocarbons gas.

A kind of 4. note critical medium oil shale single well stimulation conversion process according to claim 1, it is characterised in that：It is described Critical medium heater be donwhole heater.

A kind of 5. note critical medium oil shale single well stimulation conversion process according to claim 1, it is characterised in that：Specifically Step is：

(1) according to the distribution characteristics of oil shale layer, bung down to targeted oil shale layer and carry out completion construction；

(2) two pipelines of tripping in well, as gas injection and filling pipe and oil production tube, the wherein public pipe of gas injection and water filling Road, form gas injection and oil-producing passage；

(3) critical medium heater is put into active well with pipeline, closes well head；

(4) inject water into well and inert gas, injection rate determine according to the thickness of oil shale layer；

(5) critical medium heater is opened, oil shale is internally formed temperature as 300 DEG C -450 DEG C, pressure is the super of 9-25MPa Critical or near critical environment, the temperature and pressure in rock stratum is kept to be kept for 48 hours；

(6) in the presence of critical medium, the advantages of using its high diffusivity coefficient, high-dissolvability and low-viscosity, in oil shale The asphalitine and kerogen in portion are extracted, and oil water mixture is formed in active well.

(7) work well pressure is reduced, earth's surface oil water mixture extracting will be arrived caused by extraction by oil-producing passage, use profit point Shale oil and water are separated from equipment, separation to water be injected into by sofening treatment Posterior circle in active well, be used for Continue to extract shale oil.

(8) after the completion of the oil shale extraction work in region, the water isolated is injected into active well, the hot water recycled can It is directly injected into new active well, forms the recycling of oil shale energy.