大庆长垣高台子地区扶余油层低孔渗储层地震叠前描述技术

Prestack Seismic Descriptive Technique for Low Porosity and Low Permeability Reservoirs in Fuyu Oil Layer of Gaotaizi Area, Changyuan Tectonic Zone in Daqing Oilfield

大庆长垣高台子地区是近年储量提交重点目标区。扶余沉积时期以陆源河流相、三角洲相为主,砂岩厚度薄(一般小于5m),砂体规模小(300～600m),远小于地震极限分辨率,河道砂体识别是难题。针对存在的问题,以扶余油层河道砂体地震准确识别为目标,形成了以相对保持振幅与波形特征的高分辨率处理为基础,以优化叠加识别砂体、叠前AVO预测有效储层、叠前弹性参数反演检测油层为手段的扶余油层地震储层预测技术和流程。在研究区应用取得良好效果,曲流河点沙坝砂体得到清晰刻画,为该区寻找薄层岩性油气藏提供了可靠依据。共建议井位18口,已完钻10口,均见到较好的油气显示,试油9口,7口获工业油流,2口获低产,探井成功率达77.8%,是研究前成功率43.9%的1.78倍,较研究前有大幅度提高。

Gaotaizi area has been a major target of Changyuan tectonic zone to submit reserves in recent years. Fuyu oil layer was dominated by terrigenous fluvial faces and delta at sedimentary stage. It has thin sandstone (less than 5m in general) and small sand bodies (300m^600m), which is far lower than the seismic limiting resolution. So it is difficult to identify river sand bodies. To solve the problem, taking accurate seismic identification of river sand bodies in the oil layer as the objective, a technique and procedure for seismic reservoir predicting is developed, which is based on high resolution of relative preservation of amplitude and waveform features and employs such means as the optimal stack identification of sand bodies, the prestack AVO prediction of effective reservoirs, and the inspection of oil layer by prestack elastic parameter inversion. It has been applied well in work area, and meandering river point bar sand bodies are described clearly, laying solid basis for the discovery of thin-bed lithologic oil and gas reservoirs in the area. There are 18 recommendation wells in total, all of which have obtained good oil and gas shows. 10 wells have been drilled and completed, 9 have been tested, 7 have got commercial oil, and 2 have produced less oil. Wildcat success rate reaches 77.8%, 1.78 times higher than the 43.9% before the research is conducted.