户部寨中生界气藏裂缝识别与预测

Fracture identification and prediction of Mesozoic gas reservoir in Hubuzhai Area

 刘红磊 张雪松 郭海霞 孙艾敏

 中国石化中原油田分公司勘探开发研究院，河南 郑州 450000

 Research Institute of Exploration and Development, Zhongyuan Oilfield Company, SINOPEC, Zhengzhou 450000, China

 户部寨中生界裂缝型砂岩气藏埋藏深、储层低渗致密，但高角度裂缝发育，裂缝起到了改善储层渗流的作用。气藏采出程度低，受裂缝等因素影响，气井产能差异大，压力、产能递减快，裂缝沟通边底水容易造成气井提前见水，影响气井稳产。前人对研究区裂缝特征、分布规律等研究较少，严重制约了气藏的开发效果。文中根据岩心观察及成像测井资料，综合运用电阻率滤波差值、变尺度分析及 K 最邻近分类法开展常规测井裂缝识别，并在此基础上，应用叠前方位地震属性预测法深入研究裂缝的空间展布。结果表明：1）气藏裂缝以高角度缝为主，裂缝走向以北西向为主，与附近断层走向垂直。2）裂缝在泥质含量增多的砂岩段不发育。3）纵向上，裂缝在中生界顶部发育程度高；平面上，卫351块裂缝最为发育，卫79￣9块中部高部位裂缝相对发育，北部和南部低部位裂缝不太发育。最后指出，裂缝发育、天然气充满程度高是寻找此类气藏天然气富集区的重要条件，卫 351 块以及卫 79￣9 块中部高部位天然气富集，为气藏下步调整挖潜有利区。

 The fractured sandstone gas reservoirs of Mesozoic in Hubuzhai Area are characterized by deep buried depth, tightness and low permeability, but the well-developed fractures with high angle can play a role in improving seepage flow of reservoir. With the low recovery and being influenced by some factors such as fracture, the productivity of gas wells are very different, pressure and productivity decline fast. The connecting of fractures of edge and bottom water can easily result in water breakthrough in gas wells ahead of time and influences the stable production of gas well. Having less research on fracture characteristics and distribution regularities, the development effects of gas reservoir have been severely restricted. To carry out conventional logging identification of fractures, core data, image logging data, resistivity filter difference, variable scale analysis and K-nearest neighbor are used. Based on this, pre-stack azimuthal seismic attribute prediction of fractures is applied to research the spatial distribution of fractures. The results show that： the fractures of gas reservoir, which are mainly high angle fractures, have a trending in a direction of NW and are perpendicular to nearby faults; there are undeveloped fractures in well intervals of sandstone with the increasing shale content; there is a high development degree of fractures at the top of Mesozoic vertically; on the plane there are best-developed fractures in Block Wei 351, relatively developed fractures in the central high position of Block Wei 79-9 and less developed fractures in the low position of the north and the south. Finally it is pointed out： developed fractures and high natural gas filled degree are the important conditions for looking for natural gas enrichment areas; natural gas accumulates in the central high position of the Block Wei 351 and Wei79-9, which are the favorable areas of next adjustment and potential tapping of gas reservoir.

10.6056/dkyqt201505006