【作者】 王丹；

【导师】 马先林； 朱军；

【作者基本信息】 西安石油大学 ， 石油与天然气工程（专业学位）， 2022， 硕士

【摘要】 致密油藏储层孔隙结构错综复杂,渗透率低,体积压裂形成复杂的裂缝网络,能够有效地提高储层渗流能力。然而,通过体积压裂改造的致密储层,常规注水开发通常会引起注采系统不建立、注水不见效、见效产量递减快等一系列开发矛盾,难以实现有效开发。裂缝网络是渗吸换油的主要空间,非常有利于渗吸作用的发挥,注水吞吐已成为致密油藏的有效开发方式。本文首先对自发渗吸实验结果进行数值模拟,研究了同向渗吸与逆向渗吸的渗吸机理及差异,分析了原油粘度、基质渗透率、岩心尺寸及毛管压力对自发渗吸作用的影响,得出自发渗吸效率与基质渗透率和毛管压力呈正比,与原油粘度和岩心尺寸呈反比。其次基于长庆油田A83的储层特征及水平井钻完井参数,建立了体积压裂正交缝网及单井注水吞吐渗吸驱油模型,研究了渗吸作用对水平井产能的影响,分析了周期注水量、注入速度、焖井时间、采液速度、注入时机及吞吐轮次对注水吞吐产油效果的影响,筛选了与水平井缝网相匹配的最优注水吞吐参数。最后,建立了水平井井组吞吐模型,分析了井组间缝网连通和缝网不连通对注水吞吐效果的影响,缝网连通井组在吞吐井注水时需要关闭邻井,而缝网不连通井组则不建议邻井关闭。实例模拟结果表明,对于体积压裂水平井,注水吞吐可以有效地补充地层能量,且有利于渗吸作用的发挥,能够提高致密油藏的采收率。更多还原

【Abstract】 The pore structures of tight reservoirs are usually complex and their permeability is low.A complex fracture network is formed by volumetric fracturing,which can effectively improve the reservoir seepage capacity.However,conventional water flooding development usually causes such problems including difficult generation of injection-production system,ineffective water injection and rapid decline of oil production.Therefore,the technique is inefficient in improved oil recovery.The fracture network is the main location by imbibition to recover oil.Water huff-n-puff is an effective development method for the tight reservoirs.At first,this paper simulated experimental results of spontaneous imbibition,studied the mechanism and difference of co-current imbibition and counter-current imbibition,and investigated the effects of oil viscosity,matrix permeability,core size and capillary pressure on the spontaneous imbibition.The results show that spontaneous imbibition efficiency is proportional to matrix permeability and capillary pressure,and inversely proportional to oil viscosity and core size.Secondly,based on the reservoir characteristics and completion parameters of horizontal well in Changqing Oilfield A83,orthogonal fracture network of volumetric fracturing and single well water huff-n-puff model were established,studies the influence of imbibition effect on horizontal well productivity,analyzed the cyclic water injection,injection rate,well shut-in time,liquid production rate,injection timing and huff-n-puff rounds influence on effect of water huff-n-puff and oil production,The optimal water huff and puff parameters matching the fracture pattern of horizontal well are selected.Finally,the water huff and puff model of horizontal well group is established to analyze the influence of fracture network connectivity and disconnectivity on water huff and puff effect between well groups.The well group with fracture-connected model needs to shut down the adjacent well when water huff and puff,while the well group with fracture-disconnected model does not recommend shutting down the adjacent well.The simulation results show that water huff and puff can effectively supplement formation energy for the volume-fractured horizontal wells,and is conducive to imbibition,which can improve the recovery efficiency of the tight reservoirs.更多还原