Microcosmic mechanisms of water-oil displacement in conglomerate reservoirs in Karamay Oilfield, NW China

• Main Authors: Xu Changfu, Liu Hongxian, Qian Genbao, Qin Jianhua
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2011-12-01
• Series: Petroleum Exploration and Development
• Online Access: http://www.sciencedirect.com/science/article/pii/S1876380412600068

Targeting the conglomerate reservoir of the Lower Karamay Formation in the Middle District No.6 of Karamay Oilfield, based on the research of conglomerate reservoir characteristics and flow mechanism, laboratory experiments were conducted to study the pore production characteristics during water-oil displacement and imbibition and analyze the effect of pore structure on oil displacement efficiency, the microcosmic distribution of remaining oil and the influence of long term water flooding on reservoir pore structure. The results show that the remaining oil saturation is high, while the remaining oil is mainly in small sized pores. During the water-oil displacement, the preferential producing pores are super large pores; large and middle pores make great contributions to recovery. During the imbibition, the preferential producing pores are small pores and imbibition effect largely depends on middle and small pores. The oil displacement efficiency and microcosmic remaining oil distribution are mainly affected by pore structure. After water flooding over a long period of time, the interstitial materials expand, decentralize, move, and get eroded; large pores and throats increase; the connectivity becomes better; and the micro-heterogeneity gets more serious. 摘要: 以克拉玛依油田六-区下克拉玛依组砾岩储集层为研究对象 从砾岩储集层特征分析和渗流机理研究着手 通过室内实验 研究砾岩储集层水驱油和渗吸过程-微观孔隙动用规律 分析了孔隙结构与驱油效率关系 研究微观剩余油分布特征和长期水驱油对储集层孔隙结构的影响。研究表明目前剩余油饱和度较高 但剩余油主要分布于小孔隙之- 水驱过程- 优先动用的是超大孔隙 对采出程度起主要贡献的是-大孔隙 渗吸过程- 优先动用的是小孔隙 对渗吸作用起主要贡献的是-小孔隙 孔隙结构是影响驱油效率和微观剩余油分布的关键因素 长期水驱后 孔隙-填隙物发生膨胀、分散、运移和溶蚀 大孔道增多 连通性变好 储集层微观非均质性进一步增强。图11表5参21 关键词砾岩储集层 驱油效率 孔隙结构 核磁共振 剩余油 渗吸-图分类号TE311; TE341 文献标识码A Key words: conglomerate reservoir, oil displacement efficiency, pore structure, nuclear magnetic resonance, remaining oil, imbibition