Double-horizontal well steam assisted gravity drainage (SAGD) middle and later period exploitation method of heavy oil reservoir

Abstract

The invention provides a double-horizontal well steam assisted gravity drainage (SAGD) middle and later period exploitation method of a heavy oil reservoir. The method includes that a horizontal well is arranged in the middle of an adjacent double-horizontal SAGD well pair, a horizontal section of the horizontal well is parallel to horizontal sections of an SAGD well pair and located 1-2m above an oil layer bottom boundary, steam chambers of the adjacent double-horizontal SAGD well pair expand to be mutually combined, hot fluids are injected into the newly arranged horizontal well for huff and puff production, after 5-8 rounds of huff and puff production, a producing well is closed, the newly arranged horizontal well performs production, the hot fluids are continuously injected into the SAGD well pair, steam is injected into the SAGD well pair when yield of the newly arranged horizontal well continuously decreases for one month to reach 20t / d, production is finished when the yield of the newly arranged horizontal well decreases continuously for one month to reach a value below 3t / d, and the double-horizontal well SAGD exploitation is applied and the well distance of the adjacent double-horizontal SAGD well pair is larger than 80m in terms of the heavy oil reservoir.

Description

technical field [0001] The invention relates to a mining method for heavy oil reservoirs, in particular to a mining method for improving the SAGD mining effect of double horizontal wells in heavy oil reservoirs, and belongs to the technical field of petroleum exploitation. Background technique [0002] Steam-assisted gravity drainage technology (abbreviation: SAGD) was invented by Canada's Buter 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] The principle of SAGD is to deploy upper and lower horizontal well pairs in the same oil layer, inject high-dryness steam into the upper steam injection well, and the steam will overlap upwards in the formation to form a steam cavity because the density is much lower than that of crude oil. After injection, the steam chamber expands upwards and laterally, and exchanges heat with the crude oil in the oil layer....

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Problems solved by technology

[0004] However, for the heavy oil reservoirs in my country, due to the fluvial sedimentary environment, the reservoir heterogeneity is strong. During the development of steam-assisted gravity drainage technology, when the well spacing between adjacent SAGD well pairs is large When , the heterogeneity between wells often changes greatly, or there are discontinuously distributed interlayers, which block the uniform expansion of the steam chamber, and it is difficult for the injected steam to effectively spread and develop the reserves in the middle between adjacent well pairs; Moreover, due to the large well spacing, the flow path of crude oil in the middle position to the production well is too long, and the flow resistance is too large, which affects the effective production of the oil layer at this position to a certain extent, resulting in low recovery under the condition of large well spacing SAGD , poor economic efficiency

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