基于启动压力下稠油油田合理产能及井距研究

Research on reasonable productivity and well spacing in heavy oilfield based on threshold pressure

渤海稠油油田资源丰富,经过多年的海上探索开发,地层原油黏度小于400 m Pa·s的稠油油田也可通过注水有效开发,并取得了较好的开发效果。在开发过程中,由于稠油油藏存在启动压力,常规产能公式计算结果与实际偏差较大,无法准确描述油井合理产能;同时启动压力对井网中合理井距的确定也有一定影响,考虑启动压力时油井的动用半径与不考虑启动压力时相比,油井动用半径会缩小,因此在井网研究过程中,考虑启动压力对合理井距的确定至关重要。本文以渤海S油田为例,开展了稠油油田在注水开发过程中行列式井网合理井距研究,通过公式推导建立了稠油油藏考虑启动压力的定向井产能公式,并基于微元思想确定出距离定向井不同位置处流量贡献,根据S油田的物性及流体参数确定出S油田行列式井网开发中的合理井距,并进一步分析了不用原油黏度下油井的动用半径及合理产能。基于本文研究成果,在S油田开发调整中进行应用,并取得了较好的开发效果,本文研究方法也对渤海稠油注水开发油田定向井合理产能和合理井距的确定具有一定的借鉴意义。

Bohai heavy oilfield is rich in resources. After years of offshore exploration and development, heavy oilfields with formation viscosity less than 400 mPa·s can also be effectively developed by water injection, and good development results have been achieved. In the process of development, because of the threshold pressure of heavy oil reservoir, the calculation result of conventional productivity formula deviates greatly from the actual result,which cannot accurately describe the reasonable productivity of oil wells. At the same time,the threshold pressure has a certain influence on the determination of the reasonable well spacing in the well pattern, considering the operating radius of oil wells under threshold pressure and not considering the threshold pressure phase. In the process of well pattern study, it is very important to consider threshold pressure for determining reasonable well spacing. Taking Bohai S oilfield as an example, this paper studies the reasonable well spacing of determinant well pattern in the process of water flooding development in heavy oil-field, establishes the directional well productivity formula of heavy oil reservoir considering threshold pressure by formula deduction, and determines the flow contribution at different locations of directional well based on the thought of infinitesimal element.According to the physical properties and flow parameters of S oilfield,the reasonable well spacing in the development of determinant well pattern in S oilfield is determined, and the production radius and reasonable productivity of oil wells are further analyzed under different oil viscosity.Based on the research results of this paper, it has been applied in S oilfield development and adjustment, and has achieved good development results. The research method of this paper also has certain reference significance for the determination of reasonable directional well productivity and reasonable well spacing in heavy oil water flooding oilfield of Bohai.