塔中西部奥陶系缝洞型油藏见水特征分析

Characteristics of water breakthrough in Ordovician fractured vuggy type reservoirs in the western Tazhong area

塔中西部奥陶系缝洞型油藏以溶洞、裂缝为主要的储运空间,储层缝洞体发育,主要储层类型有洞穴型、孔洞型、裂缝型、裂缝-孔洞型,储层非均质性强,流体分布关系复杂。采用油井见水特征曲线法,以塔中西部一些典型采油井为例,结合生产数据,分析了油井见水特征,将其见水特征分为4种类型:水锥型、层状型、裂缝型、条带型。通过对研究区典型井生产动态曲线分析认为,水锥型、层状型、裂缝型见水对于日产油量下降影响达到66%左右,而条带型见水对日产油量下降影响则相对较小,不足50%。经过对研究区出水井平均含水率变化统计,平均含水率值小于60%井居多,综合认为本区尚处于低-中含水阶段。结合见水类型、生产特征及各自储层类型,提出有针对性的措施,从而达到降水增油的开发效果。

Fractured vuggy type reservoir in Ordovician reservoirs in the western Tazhong area is featured by the main reservoir spaces of cave and crack, and four types of reservoir can be subdivided ： cave - type, pore - caven, fractured - type, and fractured - cavernous type. Taking some typical oil wells in the western Tazhong area as examples, combined with produc- tion data, this paper analyzes the water breakthrough characteristics by the characteristic curves. The water breakthrough char- acteristics include four types, i. e. water coning type, laminarization type, fractured type, and banding type. Based on the ana- lyses of the production performance curves of representative oil wells, it is considered that the decrease of daily oil production of wells with＇water breakthrough of water coning type, laminarization type and fractured type, can be up to about 66%, but the corresponding number is less than 50% in wells wi.th water breakthrough of banding type. By the statistics of water - produ- cing wells in the study area,the average water -cut of major wells are less than 60% ,which indicates this area is in low - middle water breakthrough period. With the combination of water breakthrough type, production characteristics and reservoir type, pertinent measures are proposed to be helpful to the exploitation effect of reducing water and increasing oil production.