疏松砂岩油藏大孔道形成及其调堵的随机模拟

【作者】 胡书勇；

【导师】 张烈辉； 姚恒申；

【作者基本信息】 西南石油大学 ， 油气田开发工程， 2006， 博士

【摘要】 疏松砂岩油藏遍布于世界的各个油区。疏松砂岩油藏岩石胶结程度低、泥质含量高，在孔隙表面吸附着大量的粘土颗粒，在原油流动过程中极易被带走；油藏注水后，粘土遇水易发生膨胀、水化、分散、运移。因此，经过长期高速注水开发，油藏储层孔隙结构发生了较大变化，注入水对储层孔隙、骨架颗粒、胶结物和油藏流体的作用，以及油层温度和压力的变化，储层渗透率增大，孔喉半径增大，从而在储层中形成高渗带及特高渗透带，即大孔道。在大孔道发育的地层中，注入水沿大孔道无效循环，大孔道窜流严重，注入水效率低，水驱波及体积小，加剧了层内、层间矛盾，导致油井含水上升快，水驱动用程度低，影响油田采收率及开发效益的提高。而且，油田开发一旦进入中高含水期，大孔道的存在使其它增产措施实现起来也比较困难，比如调剖及注聚合物，高渗条带和大孔道同样会导致聚合物溶液窜流，不但造成聚合物浪费，而且难以形成高质量的聚合物段塞，严重影响了聚合物驱效果。 因此，加强对储层大孔道的形成机理研究、大孔道识别与描述，进而预测长期注水开采后大孔道的尺寸分布和位置分布，并进一步对储层大孔道的调堵机理进行研究，用随机模拟方法描述调堵剂在大孔道中的运动，这对于三次采油和油田堵水调剖过程中，优化聚合物和调剖剂用量、强度、段塞结构等，具有很好的指导意义，对于提高油层波及体积及石油采收率具有重要的现实意义。加强对大孔道研究的重要意义不仅仅在于指导疏松砂岩油藏中高含水期的油田开发，对于常规砂岩油藏注水开发中后期的油田开发，对于未进入中高含水期的疏松砂岩油藏开发过程中的试井、测井等动态监测技术和油井防砂等措施都具有较好的指导作用。 对疏松砂岩油藏大孔道的形成机理、识别及其调堵技术的研究，前人作了大量的研究工作，取得了一定的研究成果。但这些研究成果远未满足疏松砂岩油藏中高含水期注水开发的需要。 随着注水开发的深入，由于流体动力地质作用，使得地层特性不断发生变化，大孔道的存在加剧了这种复杂性。如何更为有效地识别大孔道，确定大孔道的粒径分布，位置分布，如何充分认识大孔道调堵技术中调堵剂的运动规律和调堵剂对大孔道的调堵机理，这是中高含水期疏松砂岩油藏开发中急需解决的课题。 本文广泛调研国内外文献，综合前人的研究成果，结合测井、地质、渗流、随机建模、计算机等多学科，取得的研究成果如下： (1)调研前人有关注水开发过程中储层物性变化的研究成果，特别是对油层大孔道的形成机理、识别技术的研究成果，对油层大孔道的形成机理加以系统化、理论化，阐明了大孔道的形成机理； (2)系统、全面地对目前现有的大孔道识别方法进行了研究，对这些方法技术进行了总结、比较，分析了各自的优缺点； (3)以达西定律、伯努里能量方程为基础，研究了单相流体在毛管中的流速公式，进更多还原

【Abstract】 Unconsolidated sandstone reservoirs are all over international various oil region .Consolidation degree of rock is weak, the shale content is high, massive clay particle adsorbed in the pore surface is being extremely easily carried away during oil mobile process, the clay meeting water is easily inflated, hydrated, dispersed, and migrated after water flooding.Therefore, the formation structure of unconsolidated sandstone reservoirs has changed distinctly after the long-term high speed water-flooding, The effects of injected water to pore structure, rock skeleton granule, bond and reservoir fluids, and the changes of reservoir temperature and pressure, make formation permeability increase, pore throat radius increase, thus high permeability or terribly high permeability zones are come into being in reservoir, namely water channel.In reservoirs exists water channels, injected water cyclically produced inefficiently along water channels, so that the utilization efficiency of the injected water is lower, meanwhile the pore volume swept by water driving is reduced, and the improvement of oil recovery and development benefit is seriously affected. Moreover, development of the fields once enters high water cut stage, water channels make stimulation measures more difficultly. for instance it can cause the polymer solution cyclically produced inefficiently, and form the high grade polymer plug with difficulty in formation, seriously affected the polymer’s effect.Therefore, strengthens to research on formation mechanism, recognition and description of water channels, and forecast its size and distribution, and further mechanism research for profile control/water shutoff, description the migration of agent to profile control/water shutoff by stochastic simulation, it is guiding significance to optimize polymerized substance and profile control agent volume , intensity , slug arrangement grade , and it has the important practical significance toward water shutoff/profile modification , sublimation reservoir swept volume and/or oil recovery factor.the vital significance of strengthens to study on water channels lies in not only the instruction development for unconsolidated sandstone reservoirs at high water cut stage, but also the good instruction function for the conventional sandstone reservoirs water-flooding development at mid and late part stage, and the dynamic monitor technology such as well test, well logging and so on for sandstone reservoirs at low water cut stage, and sand control.On formation mechanism, the recognition and plugging up technical for water channel of unconsolidated sandstone reservoirs, the predecessor has done the massive research work, and obtained the certain research results. But these research results are far not satisfied to water-flooding development need in unconsolidated sandstone reservoirs at mid and high water cut stage.Along with water-flooding development thorough, as a result of the hydrodynamics geology function, make the formation characteristic change unceasingly, and the water channels intensified the changes more complexity. How effectively distinguishes water channels, determined water channels size, position distribution, how well did know mechanism of water channel, it is a urgently topic needing to solve.更多还原