【作者】 屈乐；

【导师】 孙卫；

【作者基本信息】 西北大学 ， 矿物学、岩石学、矿床学， 2010， 硕士

【摘要】 本文针对牛圈湖油田西山窑组油藏低孔、低渗、低压的储层特征以及高含水的开发现状,运用国内外各种先进的实验方法(铸体薄片、扫描电镜、高压压汞、油水相渗、核磁共振、恒速压汞、真实砂岩微观驱替实验),系统全面研究牛圈湖油田西山窑组储层微观孔隙结构特征,同时在岩心尺度上进一步研究储层微观油水渗流机理及其影响因素,分析影响油田注水开发的主要因素,并结合超前注水、人工压裂以及超破压注水的开发方案,运用大量生产动态资料分析目前油藏见水方向及见水特征,从地质与工程两个方面分析油田高含水的主要原因。论文主要取得以下几点认识：1、西山窑储层岩石孔隙类型主要为凝灰质溶孔、粒间孔和长石溶孔,孔隙组合类型主要为晶间孔-溶孔型和粒间孔-溶孔型,喉道类型以点状喉道、片状或弯片状喉道为主,孔喉总体连通性差,配位数低,喉道半径较小,属中孔细喉型储层。2、研究区孔隙结构最明显的特征为孔喉半径大,孔隙与喉道分异性较强,流体在喉道处所受毛管阻力较大,导致储层可动流体饱和度较低,油田整体开发难度较大。3、研究区油藏主要靠油藏弹性能量驱动,但弹性驱采收率仅为1.6%。在开采过程中要保持合理的驱替压差,就必须实施超前注水的开发方式来保持地层压力。4、油水相渗曲线表现出两条明显的特征：a、含水饱和度稍有增加,油相渗透率急剧下降；b、油水两相共渗区较窄,束缚水和残余油饱和度较高。曲线特种反映了油田生产过程中油水同采的时间较短,油井见水后,产油量急剧下降,含水率快速上升。5、研究区生产井高含水的原因既有地质上的因素,又有工程上的因素。地质上的因素包括构造位置、裂缝发育、储层非均质性,工程上的原因包括超前注水实施效果、井网适应性以及人工压裂施工方式。6、研究区高含水最主要的原因为裂缝引起的水窜,裂缝主要是超破压注水和人工压裂改造形成的次生裂缝,裂缝发育方向性较强,北区裂缝以北东向展布为主,南区裂缝以北东和近东西向展布为主,裂缝形态北区较宽、南区较窄。7、牛圈湖区块超前注水实施过程中存在注入时间长,注水压力高,注水强度大等问题,生产井打开后表现出含水率上升速度快,水驱油效率低,低含水采油期短,稳产效果差等特征。8、人工压裂缝的裂缝展布方向主要受区域地应力场的控制,地层超前注水可使区域应力场发生变化,严重影响油井压裂的有效性。更多还原

【Abstract】 This article is aimed at the reservoir feature of low-porosity, low-permeability, low-pressure and the current exploitation status of high water cut in NiuJuanHu oil field. The advanced experiments have been utilized in this article, such as casting section, SEM, rule mercury penetration, water-oil displacement experiment, nuclear magnetic resonance, constant rate mercury penetration and microscopic water displacing oil experiment. The features of microscopic pore structure have been analysed completely, at the same time the microscopic water-oil filtration mechanism and the affecting factor have been researched in core yardstick. The main affecting factors of waterflood development have been analysed. Moreover, combining the development plans of advance water injection, fracture and sup-breakdown pressure injection, the orientation and feature of water breakthrough have been researched with a great quantity of production performance data, and the causes of high water cut have been found out from the aspects of geology and engineering. The article has acquired following conclusions:1.The main pore types of Xi ShanYao reservoir are tuffaceous emposieu, intergranular pore and feldspar emposieu. The types of pore combination are intercrystal pore-emposieu and intergranular pore-emposieu. The main throat types are point throat, lamellar throat and curved lamellar throat. Totally the connectedness of pore and throat is bad, the coordinate number is short, the reservoir is divided as sopore-fine throat.2.The most obvious feature of pore structure in NiuJuanHu oil field is great pore-throat radius ratio. The aeolotropism of pore and throat is obvious, and the capillary resistance is strong when fluid goes to throat, so the mobile fluid saturation of reservoir is low, and the oil is hard to be developed.3.The reservoir of NiuJuanHu oil field is drived by elastic energy, but the recovery ratio of elastic drive is only 1.6%. In order to keep appropriate displacing pressure difference in production process, the advance water injection must be implemented to raise the reservoir pressure.4.Tow obvious features have displayed in permeability ratio curve:a. When the Sw moves upward a bit, the oleic permeability drops rapidly. b. The distance of oil-water collective infiltrating fluid is narrow. The SWB and SOR are both upper. It has been reflected in permeability ratio curve that the time of oil-water simultaneous extraction is short. When water breaks through the commercial well, the crude output is dropping sharply and the water content is moving upward readily.5.The causes of high water cut in NiuJuanHu oil field include both geological and engineering factors. Geological causes include structure, split and aeolotropism, and engineering causes include the effect of advance water injection, adaptiveness of well patterns and the opportune moment of fracture.6.The main causes of high water cut is water breakthrough caused by splits. The splits are induced splits created by sup-breakdown pressure injection and hydraulic fracture. The orientation of spilts are obvious. The splits in northern area are distributed in north-east direction, and the splits in southern area are distributed in north-east and east-west direction. The northern splits are broader than southern splits.7.Many problems have arised in the implement process of dvance water injection, such as long injection time, high injection pressure, great water intake per unit thickness. When producible wells are breaked down, the water content moves upward speedily, waterflood efficiency is low, the production time with low water is short, and it is hard to stable yields.8.The orientation of fracturing splits is controlled by areal crustal stress, and the areal crustal stress can alter because of affection advance water injection, so it affects the validity of fracturing seriously.更多还原