Method for improving development effect of steam assisted gravity drainage (SAFD) through ammonium carbonate

Abstract

The invention provides a method for improving the development effect steam assisted gravity drainage (SAFD) through ammonium carbonate. The method comprises the steps that a, a double-horizontal-well pair or a vertical well-horizontal well set is arranged, wherein in the double-horizontal-well pair, a steam injection well is located above a production well, and in the vertical well-horizontal well set, a vertical well is a steam injection well, and a horizontal well is a production well; and b, in the continuous production stage of the production well, an ammonium carbonate solution is injected into the steam injection well in a continuous injection mode or a segmental injection mode till the instantaneous oil-steam ratio is decreased to 0.1-0.2, injection of the ammonium carbonate solution is stopped, and production is completed. By adoption of the technical scheme, the production degree of a deep heavy oil reservoir can be effectively improved, the heat energy utilization rate and development efficiency are improved, the recovery ratio of the oil reservoir is increased, and the development effect of the oil reservoir is improved.

Description

technical field [0001] The invention relates to a method for improving SAGD development effect by using ammonium carbonate, which belongs to the technical field of oil field recovery. Background technique [0002] Heavy oil reservoirs refer to reservoirs with a degassed crude oil viscosity greater than 100mPa·s at the reservoir temperature. At present, thermal recovery technology is widely used in the development of domestic heavy oil fields. Currently, the widely used development methods include: steam-assisted gravity drainage, steam Huff and puff, steam flooding and other technologies. [0003] Steam Assisted Gravity Drainage (SAGD) technology was invented by Dr. Butler in 1978. After more than 30 years of continuous development and improvement, a mature application technology for commercial mining has been formed. It has been successfully applied in the development of oil sands in Canada, and the development of ultra-heavy oil reservoirs in my country's Liaohe Oilfield...

AI Technical Summary

Problems solved by technology

Utilizing the properties of gas with small thermal conductivity and non-condensable gas, a heat insulation layer is formed to reduce the heat transfer rate of steam to the overlying rock layer, reduce heat loss, and improve thermal efficiency; at the same time, the non-condensable gas distributed in the upper part of the steam chamber can maintain The system pressure not only pushes the crude oil downward, but also slows down the steam’s upward overburden velocity, strengthens the lateral expansion capability of the steam chamber, and increases the steam’s lateral swept volume; The non-condensable gas affects the steam injection ability. During the operation, it is found that when the non-condensable gas is injected at the same time, the steam injection rate is reduced by about 30% due to the obvious increase in the steam chamber pressure.

Secondly, the injected gas only has the effect of heat insulation and viscosity reduction, so it can only increase the oil recovery rate, but the effect on improving the oil displacement efficiency is not obvious

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