西湖凹陷低渗储层“甜点”预测关键技术研究与应用——以黄岩A气田为例

The Key Technique Research and Application of “Sweet Spots” Prediction in the Xihu Depression of Low Permeability and Porosity Reservoir: A case study from the Huangyan-A Gas Field

西湖凹陷目的层埋藏深,储层具有低孔渗特征,通过储层改造方能释放产能,而确定"甜点"储层发育区是储层改造成功的关键。通过岩石物理分析优选低渗储层的岩性、物性及含气性敏感参数,并设定"甜点"储层敏感参数的门槛值;利用地震正演模拟分析"甜点"储层的地震反射特征,并进行孔隙度及含气性预测的可行性分析;运用相控—叠前同步反演技术得到高精度的敏感参数体,进行目的层砂体厚度、地层切片、孔隙度、含气性及脆性指数展布特征的刻画;根据地区"甜点"储层下限值圈定各属性有利区,解释优选得到目的层储层改造"甜点"有利区;依据"甜点"预测结果设计了水平井分段压裂井的井轨迹,该井的钻探结果验证了预测结果的可靠性,水平段实现了砂岩和气层的"双百"钻遇率。

Xihu sag has the characteristics of deep burial depth,low porosity and permeability,Reservoir cannot be produced at economic flow rates without assistance from reservoir reconstruction,and the prediction of ＂sweet spot＂reservoir distribution is the important process of reservoir reconstruction. The elastic parameter which is sensitive to＂sweet spot＂can be found by petro-physics analysis,and its threshold value can also be set. The characteristic of seismic reflection for ＂sweet spot＂is analyzed by seismic forward modeling,and the feasibility of porosity and gas bearing prediction can also be analyzed. The accurate parameter is predicted by pre-stack synchronous inversion with the constraint of AVO parameter,and then it describes the distribution characteristic of sand thickness,strata slices,porosity,gas bearing and brittleness index. According to the lower limit of ＂ sweet spot＂ in the study area,the favorable area of each attribute is delineated,and the favorable zone of ＂ sweet spot＂ reservoir in study area is obtained,which gives a base for the well location design of horizontal multi-stage fracturing. The prediction result is verified by drilling,furthermore,it has achieved ＂double hundred＂rate of sand and gas drilling encountered in target layer.