Method for reducing minimum miscible phase pressure between CO2 and crude oil of miscible phase displacement

A technology of miscible pressure and miscible flooding, which is applied in the new field of CO2 miscible flooding in oil reservoirs, can solve the problems of reducing the minimum miscible pressure, high minimum miscible pressure, inability to realize miscible flooding, etc., and achieves lower minimum miscible pressure and low cost. , the effect of high recovery

Inactive Publication Date: 2012-02-01
SOUTHWEST PETROLEUM UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the invention is: in order to overcome CO 2 The minimum miscible pressure with formation crude oil is high, and CO cannot be realized 2 Insufficient miscible flooding, in order to make CO 2 It is miscible with formation crude oil at a lower pressure, and it is specially provided for miscible flooding to reduce CO 2 Method of minimum miscibility pressure with crude oil

Method used

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  • Method for reducing minimum miscible phase pressure between CO2 and crude oil of miscible phase displacement

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Take 50g of high waxy crude oil with a viscosity of 20.9mPa·s at 50°C, add 0.3% isoamyl citrate to it, stir and mix thoroughly, measure its viscosity at 50°C as 9.3mPa·s, and the viscosity reduction rate is 55.5% %. It shows that isoamyl citrate has a good viscosity-reducing effect on high waxy crude oil.

[0020] According to the experimental procedures stipulated in the petroleum industry standard "SY / T 6573-2003", the crude oil sample was first tested for pure CO at a temperature of 85°C and a pressure of 22.64MPa. 2 According to the displacement experiment, the recovery rate was measured to be 76.90%; then the narrow tube was cleaned according to the experimental procedures stipulated in the standard; The sample will saturate the thin tube; after saturation, 0.3% (according to the surfactant in supercritical CO 2 Calculation of the mass concentration in, CO under 22.64MPa 2 The total injected volume is 1.2 pore volume, which is 114.274cm 3 ) of isoamyl citrate i...

Embodiment 2

[0023] Take 50g of highly waxy crude oil with a viscosity of 20.6mPa·s at 50°C, add 0.3% isoamyl citrate to it, stir and mix thoroughly, measure its viscosity at 50°C as 8.8mPa·s, and the viscosity reduction rate is 57.28 %.

[0024] According to the experimental procedures stipulated in the petroleum industry standard "SY / T 6573-2003", the crude oil sample was first tested for pure CO at a temperature of 85°C and a pressure of 18MPa. 2 According to the displacement experiment, the recovery rate was measured to be 66.60%; then the narrow tube was cleaned according to the experimental procedures stipulated in the standard; The crude oil sample will saturate the thin tube; after saturation, 0.3% (according to the surfactant in supercritical CO 2 Calculation of mass concentration in CO2 at 18MPa 2 The total injected volume is 1.2 pore volume, which is 114.274cm 3) of isoamyl citrate is injected into the thin tube at a pressure of 18MPa, and finally according to the experimenta...

Embodiment 3

[0027] 50 g of the same crude oil as in Example 1 was added with 0.2% isobutyl citrate, fully stirred and mixed, and the viscosity at 50° C. was determined to be 8.6 mPa·s, and the viscosity reduction rate was 58.9%. It shows that isobutyl citrate has a good viscosity-reducing effect on high waxy crude oil.

[0028] According to the experimental procedures stipulated in the petroleum industry standard "SY / T 6573-2003", the crude oil sample was first tested for pure CO at a temperature of 85°C and a pressure of 22.64MPa. 2 According to the displacement experiment, the recovery rate was measured to be 76.90%; then the narrow tube was cleaned according to the experimental procedures stipulated in the standard; The sample will saturate the thin tube; after saturation, 0.2% (according to the surfactant in supercritical CO 2 Calculation of the mass concentration in, CO under 22.64MPa 2 The total injected volume is 1.2 pore volume, which is 114.274cm 3 ) of isobutyl citrate is inj...

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Abstract

The invention relates to a method for reducing the minimum miscible phase pressure between CO2 and crude oil of miscible phase displacement of CO2-containing oil deposits, overcoming the defect that the minimum miscible phase pressure between the CO2 and the crude oil is high, so CO2-containing miscible phase displacement cannot be achieved. In the technical scheme, surfactant slug is injected into an oil well at first, and when surfactants are dissolved in the in-place oil, the viscosity of the in-place oil is reduced to the viscosity range of the CO2-containing miscible phase displacement; and CO2 slug is injected under the pressure of 18.00-23.00 MPa, and since the surfactants injected at first can be dissolved in the supercritical CO2, the interface tension between a gas phase and an oil phase can be reduced rapidly due to the surfactants after injection of the CO2, the minimum miscible phase pressure between the CO2 and the crude oil can be reduced, the miscible phase can be achieved rapidly, and the miscible phase displacement can be realized. The invention has dual characteristics of reducing the viscosity and decreasing the minimum miscible phase pressure; the consumption of the surfactants and the cost are low; and the recovery rate of the crude oil is 5-14 percent higher than the recovery rate in the pure CO2 displacement under the same pressure.

Description

technical field [0001] The invention relates to a CO 2 CO reduction in miscible flooding and enhanced oil recovery technologies 2 The method of minimum miscibility pressure with crude oil belongs to the reservoir CO 2 New technology for miscible drive. Background technique [0002] my country's low-permeability oil and gas reservoirs are abundant in geological reserves. The geological reserves of low-permeability oil reservoirs discovered and proven onshore in my country are about 50×10 8 t, accounting for more than half of my country's total petroleum geological reserves. It is estimated that the permeability is less than 50×10 -3 μm 2 The non-heavy oil low permeability undeveloped reserves account for more than 40% of the country's total undeveloped reserves. Facing the rapid economic development, my country's demand for oil and gas resources is increasing, and the current domestic oil reserves are relatively tight. The development and utilization of low-permeabilit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/22
Inventor 陈馥贺杰郭平焦松杰钟诚
Owner SOUTHWEST PETROLEUM UNIV
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