新疆鄯善油田微裂缝研究

在鄯善油田宏观裂缝研究的基础上，对储层微裂缝进行了研究，获得以下主要认识：１．鄯善油田发育的微裂缝按照成因分类有成岩微裂缝、颗粒微裂缝和定向微裂缝。前两种裂缝为成岩作用或破碎作用形成，后者在构造作用下形成。按照形态分类有完全充填的、不完全充填的、开启的和闭合的微裂缝。不同形态的微裂缝对注水开发的影响不同。２．该区微裂缝主要集中在０．００５～０．０２ｍｍ范围内，占全部微裂缝的７０％以上。３．微裂缝以充填为主，镜下观察８０％以上的微裂缝被碳酸钙所充填，从而大大降低了微裂缝的有效性。微观水驱油模型试验也显示，仅２０％左右的微裂缝可成为油水通道。４．微裂缝的延伸有３种情况：ａ．微裂缝中止于颗粒内部；ｂ．微裂缝延伸之颗粒边缘；ｃ．微裂缝延伸长，可切穿几个颗粒，且可与其他微裂缝形成网络。微裂缝的延伸方向主要有ＮＥ６６°、ＮＥ１３７°，其延伸方向不与大裂缝一致，夹角约为４０°。５．微裂缝在大裂缝附近较发育，受大裂缝控制。

THE STUDY OF MICRO-FRACTURES IN SHANSHAN OIL FIELD, XINGJIANG

Based on the study of macro-fracture in shanshan oilfield, we study micro-fractures andobtain the following knowledge: 1. Micro-fractures can be divided Into three types the diagenesis, particle and orientation micro-fracture according to the course of formation. Theyform in the course of diagenesis, crushing and tectonism, respectively. Micro-fractures canalso be divided into completely-filled, partly-filled, closed, and open micro-fracture on thebasis of morphology. And, different kinds of micro-fractures have different effects on thewaterflood develop. 2. Micro--fractures, whose width ranges mainly from 0. 005 to 0. 02 mm,account for 70 percent. 3. The fact that over 80 percent of micro--fractures are filled with calcium carbonate reduced their validity. Moreover, the micro water--drive test shows that only20 percent of micro-fractures can be passed through by fluid. 4. there are three kinds of extension of micro-fractures: 1) micro-fractures end in particles. 2) micro--fractures reach tothe edge of particles. 3) micro-fractures extend long enough to cut several particles and formthe network with other microMfractures. And micro-fractures, which are not parallel to rnacio-liactures at angles of about 40" between them, extend mainly along the direction of NE66"and NE137". 5. Micro--fractures develop close to macro-fractures and are as well controlled bythem.