摘要
本文针对致密碳酸盐岩孔隙度、渗透率值极低,有裂缝才具工业气流的特点,阐明了求准裂缝参数的重要性,通过8口井岩心裂缝观察,结合各测井信息在裂缝处的响应,用判别分析计算出识别裂缝的判别函数,使识别裂缝定量化。给出了三种求裂缝面视倾角的方法,并通过求椭圆积分,研究并推导出裂缝面视倾角α为任意值时的裂缝层电导率方程。该方程不仅考虑了实际裂缝面视倾角,还揭示了张开度与侧向值、视倾角、泥浆电阻率等的函数关系。计算了24口井262个裂缝层的张开度,并展示了张开度在分区评价气藏中与构造特征、产量基本吻合,为求准裂缝张开度提供了一种新的方法。
It is very important to derive fracture parameters exactly since porosity and permeability of tight carbonate are very low and commercial gas flow only exists along withfracture. Discriminant function for fracture identification is computed from core data andlog responses at fractures in eight wells by means of discrimination analysis to quantify the re-sult of fracture identification. Three methods to derive apparent dip of fracture plane α aredescribed. Via elliptic integral, conductivity equation for fracture zone is investigated and de-rived when apparent dip α is any value. This equation not only takes the apparent dip of ac-tual fracture plane into account, but also reveals the functional relation between fracture ap-erture and such parameters as laterolog data, apparent dip and mud resistivity etc. Fractureaperture of 262 fracture layers in 24 wells has been calculated, showing that the resultsbasically coincide with structural feature and production in subarea estimation of gaspool. Thus a ew method for accurate derivation of fracture aperture is given in this paper.
