疏松砂岩储层自适应高压高速冲刷注水工艺

Adaptive high pressure and high speed flushing water injection technology for unconsolidated sandstone reservoir

张璐 刘长龙 王宏玉 兰夕堂 张丽平

中海石油（中国）有限公司天津分公司渤海石油研究院，天津 300459 中国石油新疆油田分公司勘探开发研究院，新疆 克拉玛依 834000

Bohai Oil Research Institute, Tianjin Branch of CNOOC Ltd., Tianjin 300459, China Exploration and Development Research Institute, Xinjiang Oilfield Company, PetroChina, Karamay 834000, China

针对海上高孔高渗疏松砂岩储层注水井注入困难、解堵效果差的生产问题，基于试井测试数据，创新采用复合模型，将储层分区解释，首次提出疏松砂岩储层近井内区、中部存在超过常规解堵半径范围的低渗带的新特征；根据这一特征，借鉴低渗储层高压注水提压增注思路，应用MFrac Suite软件研究了不同储层物性下的裂缝延伸规律，并结合受污染储层的破裂压力、滤失机理以及RFPA￣flow岩石力学软件探索了高速冲刷水注水形成的裂缝形态。研究结果表明：疏松砂岩储层高压高速冲刷注水在储层物性条件下形成的裂缝为有利的自适应裂缝，在低渗区裂缝能够得到有效延伸；一旦突破低渗带沟通高渗带，则裂缝难以继续延伸。疏松砂岩储层高速冲刷注水形成的近井多裂缝形态更有利于改善剖面，提高注入能力。该工艺在海上油田成功开展现场试验，降压增注效果显著，基本不增加额外成本，具有推广应用价值。

In view of the production problem of difficult injection and poor plug removal effect of water injection wells in offshore unconsolidated sandstone reservoirs with high porosity and high permeability, based on well test data, the composite model is innovatively used to interpret the reservoirs in different zones, and the new feature of low permeability zone is proposed for the first time in the near and middle zones of unconsolidated sandstone reservoirs, which exceeds the conventional plug removal radius. According to the new characteristics of unconsolidated sandstone reservoir and the idea of high pressure water injection to increase pressure and water injection in low permeability reservoir, Mfrac Suite software is applied to study the fracture extension law under different reservoir physical properties. Combined with the fracture pressure and filtration mechanism of the polluted reservoir and RFPA￣flow rock mechanics software, the fracture morphology formed by high speed flushing water injection is explored. The research shows that according to the physical properties of the reservoir, the fractures formed by high pressure and high speed flushing water injection in unconsolidated sandstone reservoir are more favorable adaptive fractures, that is, the fractures can effectively extend in low permeability zone. Once the low permeability zone is broken through, the fractures in the high permeability zone are difficult to continue to extend. The multiple fractures near the well formed by high speed flushing water injection in unconsolidated sandstone reservoir are more conducive to improving the profile and injection ability. This technology has been successfully applied in offshore oil field, and the effect of depressurization and injection increase is remarkable without additional cost, so it has the value of popularization and application.

10.6056/dkyqt202302018