Gas-assisted SAGD method for exploiting super heavy oil

Abstract

The invention relates to a gas-assisted SAGD method for exploiting super heavy oil; the selecting layer thickness is 530m, remaining oil saturation is more than 0.50, oil layer thickness is more than 10.0m, horizontal permeability is more than 250md, the ratio of the vertical permeability to the horizontal permeability is more than 0.1, the oil layer porosity is more than 0.20, continuous distributed impermeable clay and intercalated shale oil pools do not exist in the oil layer; a horizontal well is drilled between soaking vertical wells, the well spacing is 35m or a pair of horizontal wells are drilled at the bottom of the oil layer, the vertical distance is 6m; swallowing is carried out for 3 stages, when the hot communication is formed between the wells, the vertical wells is used to inject steam continuously, the production of horizontal wells is 3 years, then the vertical wells is used to inject nitrogen and steam until the underground volume ratio is 0.5 and the total injection rate of nitrogen is 0.10PV, then the steam is injected continuously, the steam injection rate is 1.4m / d.ha.m, the dryness of steam at the bottom of wells is 70%, the production-injection ratio is maintained at 1.2; the recovery percent is increased by 6.0-9.0% and the oil-steam ratio is improved by 0.02-0.05.

Description

technical field [0001] The invention relates to the technical field of super-heavy oil recovery, and relates to a heavy-oil recovery method for improving steam thermal efficiency, increasing steam swept volume, and increasing oil-steam ratio. Background technique [0002] Conventional SAGD technology, as an ultra-heavy oil recovery technology, can be realized by injecting high-dryness steam through steam injection wells. The steam injection well can be a horizontal well or a vertical well, and is located directly above or laterally above the horizontal production well. Under the action of gravity, the injected steam overlaps upwards to form a steam chamber, and the heated crude oil and condensed water flow down to the production well (Fig. 1). As crude oil is produced, the vapor chamber gradually expands. Theoretical research and field practice at home and abroad show that there are two signs of successful SAGD, one is that the actual recovery rate is close to the oil reco...

AI Technical Summary

Problems solved by technology

In this steam injection method, on the one hand, the overlaying effect of high-quality steam makes the steam chamber develop rapidly upwards, and when it reaches the top of the oil layer, it will heat the overlying rock layer, resulting in ineffective waste of heat; on the other hand, due to the The heterogeneity of the steam chamber makes the expansion of the steam chamber uneven, reducing the swept volume of the steam, thereby reducing the oil recovery

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