低渗透油躲注水开发中粘土矿物的变化及作用分析.doc

低渗透油躲注水开发中粘土矿物的变化及作用分析 【中文摘要】为了防治粘土矿物在低渗透油躲注水开发过程中发生一系列物理化学反应、水化膨胀、天生沉淀或运移等引起的油层渗透率下降,油层吸水能力下降等储层损害,进步采收率,本文分析了粘土矿物的基本结构、粘土矿物微粒运移、水化膨胀机理,从理论上说明了粘土矿物对储层造成伤害的根本原因。为了更好的解释储层孔隙结构和储集性能的成因机理,本文研究了粘土矿物的含量、不同产状对孔隙结构特征、毛细管压力曲线、相对渗透率曲线、油层润湿性等的影响。研究发现在对油层孔隙特征影响方面,分散质点式粘土产状的砂岩主要渗流孔隙半径较大,薄膜式渗流孔隙半径较小,而搭桥式粘土产状的砂岩,粘土之间为微细孔隙,大部分为束缚孔隙只有少数稍大的孔隙具有一定渗透性;在对油层相对渗透率影响方面,在孔隙度相同的条件下砂岩的渗透率随着粘土矿物在孔隙中产状的不同按分散质点式、薄膜式、搭桥式的顺序依次降低。除此之外不同粘土产状对毛细管压力曲线也有不同程度的影响,各地不同粘土矿物产状砂岩之间毛细管压力曲线特征的变化规律是随着砂岩粘土矿物产状按分散质点式→薄膜式→搭桥式的变化,砂岩的排驱压力、饱和度中值压力和最小非饱和度孔隙体积增加,尤其搭桥式的排驱压力和中值压力为最大。本文借助核磁共振技术,分析了不同沉积环境下粘土矿物与可动流体的关系。结公道论分析结果,在给定油躲条件下,结合现场数据给出粘土矿物的结构及产状与油躲动态变化的联系。; 【Abstract】 In order to prevent and treat reservoir damages such as reservoir permeability plugging and water absorbing capacity decline, which are caused by a series of physical-chemical reactions and hydration expansion in waterflood development in the low-permeability reservoirs involving changes of clay mineral to produce particulate precipitation or migration, and to enhance recovery ratio, It is analyzed that the basic structure of clay minerals and the mechanism of clay mineral particles migration, hydration expansion and shown in theory the central causes of clay minerals on the reservoir damage.In order to better explain the reason for the reservoir pore structure and properties, it is studied in this article the effect of content and different occurrence of clay minerals on property of pore structure, capillary pressure curve, relative permeability curve and reservoir wettability and so on. It is found that on the impact of pore characteristics, the main seepage pore radius of dispersed particle clay occurrence of sandstone is larger, pore radius of membrane clay occurrence is smaller, and for bridge tycle clay occurrence, there are micro-pore among clays, the most is irreducible pore, only a handful of pores are larger and have certain permeability in the reservoir; on the impact of the relative permeability, the permeability of sandstone, under the same porosity, is dropping as the different occurrence of clay minerals, the order is dispersed particle, membrane and bridge tycle. In addition, the different occurrence have varied degrees impact on capillary pressure curve, the variational law of capillary pressure curve characteristics between different sandstone clay occurrence is that with different clay occurrence, expulsion pressure,saturation median pressure and the minimum non-saturation pore volume increase in the order of dispersed particle, membrane and bridge type clay occurrence, especially the expulsion pressure and median pressure of bridge type occurrence is greatest.With nuclear magnetic resonance technology, It is analyzed that the relationgship between clay minerals and movable fluids under different sedimentary environments. Then combined with the field data and the results of theoretical analyses ,the ties between the structure and occurrence of clay minerals and reservoir perance variation are given.