建南地区须四段致密砂岩含气储层预测研究

建南地区须四段为典型的致密砂岩气地层,其中砂体较厚、砂泥岩互层较多,但储层较薄,尤其是地震响应不清晰,为含气储层的预测增加了难度。为此,以工区储层地质特征为指导,从单井岩石物理分析入手,结合采用叠前弹性反演和AVO分析方法对该区须四段的含气储层分布进行综合预测。储层预测分析表明,本区须四段的储层敏感属性参数对为纵波阻抗(Zp)与纵横波速度比(Vp/Vs),经两者融合的储层因子属性的正高值区可解释为储层砂体的有利发育区;须四段气层主要表现为第Ⅳ类AVO异常响应特征,且该层含气敏感属性为泊松比(PR)、流体因子(FF)、相对纵波速度(DVp),并将三者叠加的烃类因子属性的负异常区域解释为储层有利含气区。最后经综合预测可知,须四段含气储层有效厚度分布在28~80 m之间;且在建35-2井、新店1井周缘区域厚度较大。

Predicting tight gas-bearing sandstone reservoir of the 4th Xijiahe Formation in Jiannan area

The 4th Xijiahe Formation in Jiannan area is a typical tight gas sand layer, which have thick sand bodies interberded in thin shale layers, with a thin reservoir and unclear seismic response, increasing the difficulty for its reservoir prediction. Taking theSgeological characteristics of the reservoirSas a guide and based on the single well rock physics analysis, theSprestackSelastic inversionSis combined withSAVO analysis method to do comprehensiveSprediction of theSdistribution of gas in the reservoir in this area. The analysis show that, the reservoirSsensitive attributeSparameters of the 4th Xijiahe Formation areSP-wave impedance (Zp)SandSP/S wave velocity ratio (Vp/Vs). Integrating these two parameters gives the reservoir factor which is taken as aSfavorable distribution areaSof the reservoir sandSbody when it is a high value. The 4th Xijiahe FormationSmainly indicates the class IVSAVOSabnormal response feature,Sand theSreservoir gasSsensitiveSattibutes areSPoisson"s ratio(PR),Sfluid factor(FF),SrelativeSP-wave velocity (DVp) , SIntegrating these parameters also give the hydrocarbon factor which is taken asSa favorable gas bearingSareaSof reservoir when a anomaly isSnegative. Finally,Sthe comprehensive prediction shows that, the gas bearing reservoir of the 4th Xijiahe Formation has the thickness between 28-80m and has large thickness in the Jian 35-2 well and Xindian 1 well areas.