利用多属性融合方法预测新疆滴西178井区梧桐沟组薄砂岩储层

Prediction of thin sandstone reservoirs of Wutonggou Formation in the DX178 well area of Xinjiang by using liquid mobility factor method

滴西178井区梧桐沟组发育上、下2套气层,天然气地质储量为31.49×108 m3,是下步开发建产的有利区。但是梧桐沟组储层构造幅度低、砂体薄,现有地震资料频率较低,勘探开发的投资成本高、风险大,因此要提高水平井砂体的钻遇率,对薄砂体识别方法的研究至关重要。常规叠后地震反演方法能够识别厚度较大的砂岩储层,但对较薄的砂体由于受到地震分辨率的限制,预测结果不能满足勘探开发的需要。在精细地震资料处理基础上,基于波形特征、阻抗属性和烃类活动因子属性,结合测井信息,对砂体厚度进行多属性融合预测,刻画出滴西178井区梧桐沟组砂体发育分布区,并利用预测结果部署实施了4口水平井。预测结果与钻井、气测结果吻合,有效地提高了水平井砂体钻遇率,取得了良好的开发效果。

The Wutonggou Formation in the DX178 well area develops two sets of upper and lower gas layers with natural gas geological reserves of 31.49×10^8 m^3,which is a favorable area for the next step to development and production.However,the reservoir in the Wutonggou Formation is thin,and the frequency of existing seismic data is relatively low.The investment cost for exploration and development is high and the risk is large.Therefore,it is necessary to improve the sand drilling rate of horizontal well and study on the identification method of thin sand.The sandstone reservoirs with large thickness can be merely identified by conventional post-stack seismic inversion method.Owing to the limitation of seismic resolution for the thin sand,the prediction results cannot meet the needs of exploration and development.In this paper,the liquid mobility factor calculated by the high-precision seismic time-frequency analysis method can effectively characterize the sandstone reservoir and non-reservoir layers.According to the logging data,the fluid activity factor of the sandstone reservoir was calibrated by the liquid mobility factor,and the distribution area of sandstone can also be predicted.This method was used to predict the thin sandstone reservoirs of the Wutonggou Formation in DX178 wells area.The prediction results are in good agreement with the actual drilling results.During the implementation process of the four horizontal well drilling,the well trajectory was timely adjusted according to the prediction results,which effectively improved the sand drilling rate of horizontal well,and achieved good development results.