Method for exploiting natural fracture heavy oil reservoir using steam assisted gravity drainage (SAGD) assisted by degradable temporary plugging agent

Abstract

The invention discloses a method for exploiting natural fracture heavy oil reservoir using steam assisted gravity drainage (SAGD) assisted by a degradable temporary plugging agent. The method comprises the following steps that a high-temperature-resistant degradable temporary plugging agent is injected, the temporary plugging agent enters an area where natural fractures or high permeability zones communicate with each another, gel is generated in the natural fractures, and thus a plugging action is played on the fractures; after the high-temperature-resistant degradable temporary plugging agent is injected, a pressure test is carried out, and whether the natural fractures or the high permeability zones are plugged successfully or not is judged by observing the comparison of the injection flow rate and the injection pressure; after plugging is successful, the dilatancy operation is carried out on the whole horizontal sections of injection-production wells; and after the dilatancy operation is completed, high temperature steam is injected into the injection-production wells to carry out conventional thermal cycle, and thermal communication between the injection-production wells is formed. According to the method for exploiting the natural fracture heavy oil reservoir using the SAGD assisted by the degradable temporary plugging agent, the degradable temporary plugging agent can be applied to pluggling of the natural fractures in an SAGD application oil layer, the well bottom injection pressure required for rapid preheating is realized, the preheating cycle is shortened, the steam injection consumption and cost are reduced, the thermal efficiency of heavy oil exploitation is improved, and the economic benefits are increased.

Description

technical field [0001] The invention relates to a method for utilizing a degradable temporary plugging agent to assist SAGD in exploiting natural fracture heavy oil reservoirs, and belongs to the technical field of petroleum engineering oil and gas field development. Background technique [0002] Steam-assisted gravity drainage (SAGD) is a cutting-edge technology for the development of heavy oil reservoirs. The application of SAGD technology is mainly carried out on two vertically parallel horizontal wells, in which the upper horizontal well is used as an injection well, and the lower horizontal well is used as a production well ( figure 1 ). The first stage of the application of SAGD technology is the cycle preheating stage, that is, to establish thermal communication between the oil layer between the injection well and the production well through different heating methods, so that the injected steam can continuously flow into the oil layer, and the heated crude oil and co...

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Problems solved by technology

However, if this method is applied to formations with natural fractures, the injected fluid will easily leak into the formation along the natural fractures

Moreover, it is possible to form the main channel between injection and production wells through natural fractures, so that most of the injected steam will be lost through the main channel, resulting in uneven preheating and fluid communication, and under the conditions of initial hot water injection or low steam rate, The required injection pressure cannot be achieved at the bottom of the well, and it is difficult to achieve the purpose of near-well expansion and rapid preheating ( image 3 )

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