SAGD starting method for interlayer heterogeneous thickened oil pool

Abstract

The invention provides an SAGD starting method for an interlayer heterogeneous thickened oil pool. According to the interlayer heterogeneous thickened oil pool in the method, an interlayer exists between horizontal segments of an injection well and a production well, the spreading range of the interlayer along the horizontal segments does not exceed half length of the horizontal segments, and the thickness of the interlayer ranges from 0.3 m to 3 m. The method specifically comprises the steps that steam injection equipressure cycle preheating is carried out on the steam injection well and the production well; according to the different positions of the interlayer between the injection well and the production well, the different modes are adopted to carry out steam injection of the steam injection well and cycle preheating of the production well; according to the different positions of the interlayer between the injection well and the production well, the different modes are adopted to carry out alternative injection and production; a long pipe and a short pipe of the steam injection well carry out pure steam injection at the same time, a long pipe and a short pipe of the production well drain liquid at the same time, then, the step is converted into the SAGD production stage, and the SAGD starting method for the interlayer heterogeneous thickened oil pool is completed. According to the method, uniform development of a steam cavity of the SAGD horizontal segments can be achieved, and the oil production and the recovery efficiency are effectively improved.

Description

technical field [0001] The invention relates to a mining method for heavy oil reservoirs in oil fields, in particular to a start-up method for exploiting heterogeneous heavy oil reservoirs with interlayers between injection and production wells using steam-assisted gravity drainage technology, which belongs to petroleum exploitation field. Background technique [0002] Steam-assisted gravity drainage technology (abbreviation: SAGD) was invented by Canadian Butter in 1978, and has been successfully applied in heavy oil reservoirs in Canada's oil sands mining area, my country's Liaohe Oilfield, Xinjiang Oilfield and other places. [0003] SAGD deploys stacked horizontal well pairs in the same oil layer, and injects high-dryness steam into the upper steam injection well. Since the density of steam is much lower than that of crude oil, it overlaps upwards in the formation to form a steam cavity. With the continuous injection of steam , the steam chamber continuously expands upw...

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Problems solved by technology

[0007] Because the heavy oil reservoirs in Liaohe, Xinjiang and other places belong to fluvial facies deposition, the reservoirs have strong heterogeneity, and lateral accretion interlayers are developed at the edge of the channel, especially the existence of interlayers between injection and production wells has a great influence on the drainage between injection and production wells of SAGD. The oil channel has an important influence. In the part where the interlayer is developed between the injection and production wells, it is difficult to establish an oil drainage channel in the part where there is a continuous interlayer between the injection and production wells, so that it is difficult to develop steam in this part. cavity, the steam cavity on the horizontal section cannot expand uniformly, and the expansion size and uniformity of the steam cavity are proportional to the production of the oil well

Field practice in the oil field shows that for SAGD development with interlayers between injection and production wells, the conventional cycle preheating start-up method seriously affects the development of steam chambers in the horizontal section and the production and recovery of SAGD wells

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