阿北安山岩油藏裂缝发育特征对开发的影响

The effect of growth fracture of Abei Andesite reservoir on oilfield development.

阿北安山岩油藏位于二连盆地阿南凹陷阿尔善构造带中部，储集体是多套安山岩层（岩流层或熔岩体）叠加形成的裂缝-孔隙型储集层，裂缝（尤其是次生裂缝）是主要的渗滤通道，有效储集层集中分布于裂缝发育的安山岩层上部。阿北安山岩油藏注水开发1a后产量就快速递减，裂缝对开发的影响表现为：①投产初期，缝孔段厚度越大且裂缝越发育，单井产量越高；②注水开发阶段，受效较好、产量高而稳定的油井主要分布于断层附近或构造高部位；③由于裂缝发育差异，注水开发过程中油井含水上升规律可分为4种类型（注水不受效型，微细裂缝受效型，裂缝水驱型，早期水淹型）。该油藏裂缝发育的油井开发初期压裂效果好，注水开发形成低压低产的油井压裂效果差，分采分注和堵水措施无效，结合化学调剖的周期注水效果较好。研究裂缝分布发育规律及对开发的影响，可以为注水开发中、后期动用导流大裂缝之间微细裂缝中的原油提供科学依据。图1参2（王孝陵摘）

Abei Andesite reservoir is located in the central Arshan structure of Anan depression, Erlian basin. Its reservoir rocks are of fracture-porous type which are superimposed by many sets of andesitic strata (rock flowage or karst deposits). The fractures (specially secondary fractures ) are the main seepage path; effective reservoirs are mainly located in the top of Andesite strata with growth fractures. The production of Abei Andesite reservoir declines quickly after water injection. The effect of the fracture on oilfield development is mainly characterized by: (1) At early stage of development, the thicker the fractured zone is, the better developed the fracture is, the higher the production of single well will be; (2) At water injection stage, these high and stable production wells are mainly near the faults or in the high position of the structure; (3) Because of the difference of their fracture development, the pattern of the increase of water cut of oil production wells during water flooding can be divided into 4 types: inefficient water flooding, effective for microfractures, water flooding in fractures and early water-flooded. In the early field life, wells that are located in the area where the fractures are developed have good response in the fracture treatment; while the wells with low pressure and low production have no good response after water flooding in the fracture treatment and have no response with zonal injection, zonal recovery and water plugging, but they have good results from cyclic water flooding combined with chemical profile modification agent. The research on the distribution and the growth law of fractures as well as their effects on oilfield development will be able to provide scientific basis for producing the crude oil remaining in microfractures between big fractures in the medium and the late phases of water flooding development.