四川盆地新场气田致密砂岩裂缝预测技术研究

Research of Fracture Prediction Technology in Tight Sandstone Gas Reservoir in Xinchang Gas Filed of Sichuan Basin

四川盆地新场气田三叠系须家河组砂岩气藏是一个致密砂岩裂缝型气藏。储集层的基质孔隙度很低,平均只有3.8%,基质渗透率低于0.3 mD,以裂缝贡献渗透率为主。通过采用新一代三维空间全局寻优离散扫描技术,精确扫描地震轴的产状,分析井上裂缝密度与精细扫描后各种地震几何属性关系,指出利用像素成像属性预测大尺度裂缝、利用曲率属性预测小尺度裂缝是有效的。在裂缝分析基础上找到研究区裂缝发育特点,利用岩性和曲率属性做约束,由井出发预测地震级别的大尺度裂缝和小尺度网状缝的密度。结合构造部位和生产井生产状况,指出在有利储集层圈定前提下,构造高部位的裂缝发育区是有利的勘探开发区。

The Triassic sandstone gas reservoir in Xujiahe formation is a type of tight sandstone fractured reser- voir in Xinchang gas field of Sicbuan Basin. The matrix porosity is very low, and the average porosity is just 3.8%. The matrix permeability is less than 0.3 roD, while the permeability of gas reservoir is mainly provided by fractures. Adopting the new generation global optimization discrete scanning technology in three-dimensional space, the seismic event occurrence can be scanned accurately. By means of anslysing the relationship between fracture density of wells and seismic geometric attributes scanned precisely, it is concluded that pixel imaging attribute is ef- fective to predict large scale fracture and curvature attribute is effective to small scale fracture. The fracture devel- opment characteristics based on fracture analysis, making use of lithology and curvature attribute as constraints, start- ing from the well data, the density of the large scale fracture with seismic level and small scale net fracture can be predicted. According to the structure position and the producting condition of production wells, the area with fractures developed in structural high part is the advantageous area for exploration and development on condition that good res- ervoir is sure.