A method for rapid start-up of steam-assisted gravity drainage in heavy oil reservoirs

Abstract

The invention discloses a rapid start method for heavy oil reservoir steam assisted gravity drainage. The rapid start method for heavy oil reservoir steam assisted gravity drainage comprises the following steps that (1) a steam injection well and a producing well are electrically heated at a large power; (2) a solvent is injected into a long oil pipe and a short oil pipe of the steam injection well and a long oil pipe and a short oil pipe of the producing well at the same time; (3) a solvent and steam liquid mixture is injected into the long oil pipe and the short oil pipe of the steam injection well at the same time, the solvent and steam liquid mixture is injected into the long oil pipe of the producing well, and the short oil pipe of the producing well discharges liquid; (4) electric heating is stopped, pure steam is injected into the long oil pipe of the steam injection well and the short oil pipe of the seam injection well at the same time, and the long oil pipe and the short oil pipe of the producing well discharge liquid at the same time. Compared with a conventional preheating start method, time is shortened by over two thirds, so that the heat energy utilization rate is greatly increased, rapid preheating start of SAGD can be achieved, and the production speed of SAGD is increased. In addition, through rapid solvent volume expansion and super fracture pressure injection, an even oil drainage channel can be established, and the purposes of increasing the yield and the recovery rate are achieved.

Description

technical field [0001] The invention relates to a method for exploiting heavy oil reservoirs in oil fields, in particular to a quick start method for steam-assisted gravity drainage (SAGD) of heavy oil reservoirs. 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. The principle is to deploy upper and lower horizontal well pairs in the same oil layer, and inject high-dryness steam into the upper steam injection well. The steam is much denser than crude oil, and the steam overlaps upwards in the formation to form a steam cavity. With the continuous injection of steam , the steam chamber continuously expands upwards and sideways, and exchanges heat with the crude oil in the oil layer. The viscosity of the heated crude oil is reduced, and t...

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Problems solved by technology

Therefore, a large amount of steam and a large amount of heat energy will be consumed in the cycle preheating stage, resulting in too long preheating time of SAGD, high initial mining cost and slow production rate

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