裂缝型储层应力敏感与裂缝角度关系实验研究

EXPERIMENTAL STUDY ON RELATIONSHIP bE-TWEEN STRESS SENSITIVITY AND FRACTURE ANGLE OF FRACTURED RESERVOIR

裂缝型油气藏是目前研究的热点油气藏之一。储层裂缝发育的复杂性和多样性决定了该类型油气藏开发的困难性,一方面裂缝的存在能够改善渗流通道,但其具有一定的应力敏感特征,会对储层造成一定程度的损害,导致渗透率下降,影响储层的开采效率。因此,在油气藏开发过程中对裂缝型储层进行应力敏感性评价至关重要。文章以某高温、高压裂缝型储层为研究对象,通过实验的方法测定了不同围压下渗透率随有效应力的变化规律,对比了人工裂缝和天然裂缝应力敏感性的区别,并分析了裂缝角度与应力敏感系数之间的关系。实验表明,该区块应力敏感程度中等偏强,人工裂缝的应力敏感程度略高于天然裂缝,应力敏感系数随角度的增加呈线性变化关系。

Fractured reservoir is one of the hotspots in oil and gas reservoirs. The complexity and diversity of fracture development decide the difficulty of the oil and gas reservoir development. On one hand,the cracks can improve the seepage passage,but its stress sensitivity will cause some damage to the reservoir,resulting in decreased permeability and reduced reservoir development efficiency. Therefore it is very important to evaluate the stress sensitivity of fractured reservoirs. In this paper a high temperature and high pressure fractured reservoir at Xinjiang is taken as the study object,how the permeability varies with the effective stress at different confining pressures is studied by experiments. The differences of stress sensitivity between the artificial fractures and natural fractures are analyzed,and the relationship of crack angle and stress sensitivity coefficient is studied. The experiments show that the stress sensitivity at the block is moderate,the stress sensitivity of artificial fractures is slightly higher than that of natural fractures. And the stress sensitive coefficient varies linearly with the increase of angle.