川东北元坝东部须四段裂缝型致密砂岩储层预测

Prediction for fractured tight sandstone reservoir of Xu 4 member in eastern Yuanba area,northeastern Sichuan Basin

裂缝型致密砂岩储层是四川盆地三叠系须家河组重要的储层类型,由于该类储层具有低孔、低渗、强非均质性特征,其储层的预测是川东北油气勘探开发的重点和难点。为准确预测该类储层的分布,提出了"相控找砂,砂中找缝"的"两步法"技术思路,针对目标靶区,综合地质地震资料开展砂体展布及裂缝预测。该方法利用地震多属性综合与相控地震反演技术,定性和定量预测有利砂体分布区;结合叠前叠后裂缝检测技术、基于断-缝联系法和储-盖差异法的断裂-裂缝有效性评价技术,评价断裂-裂缝发育带;最终综合有利砂体和裂缝分布区圈定优质储层发育带。预测结果经后期钻井证实可靠性较高,表明该技术思路对裂缝型致密储层预测具有借鉴意义。

The tight-fracture reservoir is an important reservoir type of Triassic Xujiahe Formation in Sichuan Ba- sin. Since the reservoir has low porosity, low permeability and strong heterogeneity characteristics, the accurate prediction of properties of Xujiahe Formation is the key and difficult point of oil and gas exploration and develop- ment in northeastern Sichuan Basin. Facing with these problems, We proposed a theoretical workflow of reser- voir prediction. The main idea of our workflow is to define sand in face and define fracture in sand. Firstly, the distribution of favorable sand was predicted by seismic attributes and seismic inversion on the basis of facies-con- trolled techniques; then using pre-stack and post-stack technology to predict multi-scale fractures, at the same time, based on the method of relation of fault-fracture and difference of reservoir-cap to evaluate effective fault- fracture system; Finally, considering the prediction result of sand and fractures point out the favorable exploration target area. The reliability of our method has been testified by comparing with drilling data, and we believe our method can be used to predict others tight sandy reservoir.