Method for improving ordinary heavy oil reservoir recovery ratio by adopting chemical agents to assist CO2 huff and puff

A technology of heavy oil reservoirs and chemical agents, which is applied in the direction of production fluid, earthwork drilling, wellbore/well components, etc., and can solve the problems of periodic oil production, oil-gas ratio decline, large difference in oil-gas velocity, and small swept volume, etc. problems, to achieve the effect of reducing the flow resistance of crude oil, reducing the viscosity of crude oil, and reducing the flow resistance of heavy oil

Active Publication Date: 2016-09-21

CHINA UNIV OF PETROLEUM (EAST CHINA)

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AI-Extracted Technical Summary

Problems solved by technology

However, ordinary heavy oil wells carry out multiple rounds of CO 2 After the huff and puff, due to the large difference in oil and gas velocity, the CO 2 The...

Method used

[0038] (4) after one week, well production. The addition of foaming agent solution can increase the volume of CO2 gas sweep, control the flow rate of CO...

Abstract

The invention relates to a method for improving the ordinary heavy oil reservoir recovery ratio by adopting chemical agents to assist CO2 huff and puff. The method is characterized by combining the chemical agents with CO2 huff and puff, firstly injecting a viscosity reducer or foaming agent type chemical agent solution slug into an oil well undergoing multiple rounds of CO2 huff and puff, later injecting a high pressure CO2 slug into the well and carrying out soaking after injection is completed. The method has the advantages that during soaking, the viscosity reducer type chemical agents and the ordinary heavy oil form oil-in-water type emulsion, thus substantially reducing the oil-water interfacial tension and reducing the crude oil flow resistance during exploitation; the CO2 gas phase mobility can be controlled and CO2 can be effectively prevented from gas channeling through addition of the foaming agent type chemical agents, so that CO2 diffuses toward the depth of the stratum and the CO2 wave and volume are increased; and due to synergy of the chemical agents and CO2, the oil well can still maintain higher oil production after multiple rounds of huff and puff.

Application Domain

Fluid removal

Technology Topic

Oil productionEnvironmental geology +11

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Examples

Experimental program(3)

Example Embodiment

[0032] Example 1

[0033] A chemical agent assisted CO 2 The method of huffing and puff to improve the recovery of ordinary heavy oil reservoirs, the process is as follows figure 1 As shown, the high-pressure CO 2 The outlet of the storage tank 1 is connected to the ground injection device 2, which is connected to the ground injection device 2 and the injection well 3 through a pipeline, the foaming agent aqueous solution storage tank 4 is connected to the ground injection equipment 2 through the pipeline, and the ground injection device 2 and the injection well are connected through the pipeline 3.

[0034] The specific steps are as follows:

[0035] (1) The foaming agent solution slug injection process: The bis-(2-ethylhexyl)-sulfosuccinate sodium succinate foaming agent is formulated into a foaming agent aqueous solution, which is injected into the formation from the wellbore, and the mass concentration of the foaming agent aqueous solution 0.5%, the volume of the foaming agent aqueous solution injected is 15m 3;

[0036] (2) High pressure CO 2 Slug injection process: CO 2 The slug is pressurized by the surface pressurization equipment and injected into the reservoir from the wellbore. Under the conditions of the injected reservoir, CO 2 The volume ratio of the injected chemical agent aqueous solution is 2:1;

[0037] (3) Braised well diffusion: CO 2 After the oil layer was injected, the well was shut in for simmering. The simmering time was 7 days, and the pressure changes during the simmering process were recorded. CO during simmering 2 Extraction, volume expansion, dissolution and viscosity reduction with crude oil;

[0038] (4) One week later, the well is opened for production. The addition of foaming agent solution can increase CO 2 Swept volume of gas, control CO 2 Fluidity, effectively preventing CO 2 Gas channeling occurred. CO 2 Gas displaces crude oil from the oil layer to the wellbore, and finally to the surface;

[0039] (5) Waiting for a round of foaming agent auxiliary CO 2 After the throughput is over, repeat steps (1) to (4) 3 times to achieve multiple rounds of foaming agent auxiliary CO 2 Throughput, improve CO for multiple rounds 2 Throughput oil production.

Example Embodiment

[0040] Example 2

[0041] A chemical agent assisted CO 2 The method of huffing and puffing to improve the recovery of ordinary heavy oil reservoirs includes the following steps:

[0042] (1) Slug injection process of viscosity reducer solution: formulate alkyl sulfonate viscosity reducer into an aqueous solution of viscosity reducer and inject it into the formation from the wellbore. The mass concentration of the aqueous solution of viscosity reducer is 1.0%, and the aqueous solution of viscosity reducer is injected The volume is 12m 3;

[0043] (2) High pressure CO 2 Slug injection process: CO 2 The slug is pressurized by the surface pressurization equipment and injected into the reservoir from the wellbore. Under the conditions of the injected reservoir, CO 2 The volume ratio of the injected chemical agent aqueous solution is 1:1;

[0044] (3) Braised well diffusion: CO 2 After injection into the oil layer, the well was shut in for simmering for 10 days, and the pressure changes during the simmering process were recorded. During the simmering process, the viscosity reducer and the ordinary heavy oil form an oil-in-water emulsion, which greatly reduces the viscosity of the crude oil. 2 Extraction, volume expansion, dissolution and viscosity reduction with crude oil;

[0045] (4) After the simmering well is completed, the well is opened for production. In the process of formation seepage, CO 2 Mixed with oil and water emulsion, CO 2 The gas displaces crude oil and the emulsion flows from the formation to the wellbore, and finally to the surface.

[0046] (5) Wait for a round of viscosity reducer auxiliary CO 2 After the throughput is over, repeat steps (1) to (4) 4 times to achieve multiple rounds of viscosity reducer assisted CO 2 Throughput, improve CO for multiple rounds 2 Throughput oil production.

Example Embodiment

[0047] Example 3

[0048] Simulated chemical agent auxiliary CO 2 The experimental equipment for huffing and puffing ordinary heavy oil reservoirs is mainly composed of a double plunger metering pump for displacing liquid, a double plunger metering pump for displacing gas, pressure transmitter, balance, sand filling pipe, temperature and pressure control and recording system, etc. Composition, the experiment is carried out under constant temperature and pressure to simulate the reservoir environment.

[0049] The specific steps are:

[0050] (1) Fill a core with a certain permeability using a sand-filled pipe, weigh the dry weight, vacuum, saturate the water, weigh the wet weight, calculate the porosity, and determine the core water permeability;

[0051] (2) Adjust the core to a formation temperature of 60℃ and formation pressure;

[0052] (3) Saturate the oil at a rate of 0.5ml/min until the output liquid does not contain water at the outlet end, close the core outlet end and stabilize for a period of time;

[0053] (4) Inject CO at a rate of 0.5ml/min from the injection end 2 When CO 2 When the injection volume reaches 24ml, stop gas injection, close the injection end and simmer the well for 12 hours;

[0054] (5) Open the valve at the injection end to spit out oil and gas under a pressure drop gradient of 1 MPa/min, and record the oil production;

[0055] (6) Repeat step (4) ~ step (5) for the next round of CO 2 Throughput experiment

[0056] (7) The foaming agent fatty acid polyoxyethylene polyoxypropylene ether (C 12 E 9 P 3 ) Dissolve in formation water to prepare a solution with a mass concentration of 0.5%, and pour it into an intermediate container;

[0057] (8) Inject the foaming agent solution slug from the injection end at a speed of 1ml/min. When the fatty acid polyoxyethylene polyoxypropylene ether (C 12 E 9 P 3 ) When the injection volume of foaming agent solution reaches 12ml, stop the injection, and then inject 24ml of high-pressure CO 2 Slug, close the injection end and simmer the well for a certain period of time;

[0058] (9) After simmering the well for 12 hours, open the valve at the injection end to spit out the oil, gas, and foaming agent solution under a pressure drop gradient of 1 MPa/min, and record the oil production;

[0059] (10) One round of foaming agent auxiliary CO 2 After the throughput is over, repeat steps (8) to (9) three times to achieve 4 rounds of foaming agent auxiliary CO 2 Huff.

[0060] (11) Contrast CO 2 Huff and puff to displace crude oil and inject 24ml of high-pressure CO 2 , Do not inject the foaming agent solution, close the valve at the injection end and start the well after 12h simmering, record the cycle oil production of the well-opened production, and perform 6 rounds of CO 2 Huff.

[0061] The experimental results are as figure 2 As shown, contrast chemical agent assisted CO 2 Throughput and CO 2 Throughput, chemical agent assisted CO 2 Huff and puff has a higher recovery rate. After 6 huff and puff rounds, the total recovery rate reached 41.96%, and a good mining effect was achieved.

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Classification and recommendation of technical efficacy words

reduce crude oil viscosity

Method for improving ordinary heavy oil reservoir recovery ratio by adopting chemical agents to assist CO2 huff and puff

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

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Examples

Example Embodiment

Example Embodiment

Example Embodiment

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Description & Claims & Application Information

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