Later-period air injection exploitation method for super heavy oil reservoir using steam assisted gravity drainage (SAGD) exploitation

Abstract

The invention relates to a later-period air injection exploitation method for super heavy oil reservoir using steam assisted gravity drainage (SAGD) exploitation. The method comprises the following steps of: newly drilling a straight well as an air injection well at a position where a steam cavity of the super heavy oil reservoir develops poorly; perforating on the upper part of the air injection well to complement a perforation section with the length of 2-3m; continuously injecting air by the air injection well at the speed of 20,000-80,000m<3> / day and firing to exploit; and stopping injecting the air when the volume percentage of the oxygen in the produced gas reaches 3 percent or the volume ratio of the volume of the injected air and the volume of the produced crude oil reaches over 3,000m<3> / m<3>. With the adoption of the method, the later-period heat loss is reduced by using the SAGD technology, and the stable production of the whole system is maintained by utilizing heat energy released by reacting substances in the oil reservoir.

Description

technical field [0001] The invention relates to a post-exploitation method of an ultra-heavy oil reservoir, in particular to an air-injection extraction method in the late stage of SAGD exploitation of an ultra-heavy oil reservoir, belonging to the technical field of petroleum exploitation. Background technique [0002] Conventional Steam-Assisted Gravity Drainage (SAGD) technology, as a super-heavy oil recovery technology, can be realized by injecting high-quality 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 covers upward to form a steam chamber, and the heated crude oil and condensed water flow down to the production well (such as Figure 1a with Figure 1b shown). As crude oil is produced, the vapor chamber gradually expands. Theoretical research and field practice at home and abro...

AI Technical Summary

Problems solved by technology

In this way of steam injection, on the one hand, the overlying effect of high-quality steam makes the steam chamber develop rapidly upward, and when it reaches the top of the oil layer, it will heat the overlying rock layer, resulting in ineffective waste of heat, especially in the late stage of SAGD (late stage of SAGD refers to the stage when the production of SAGD production wells passed the peak period and began to have a clear decreasing trend), this kind of energy waste is more serious; on the other hand, due to the heterogeneity of the reservoir, the expansion of the steam chamber is not uniform, Reduces the producing volume of the reservoir, thereby reducing oil recovery

[0004] Moreover, it is recognized that the recovery rate of SAGD can reach more than 60%, but there is no public report on whether the recovery rate can be further improved

Images