叠前同时反演在吐哈盆地致密油气有利储层预测中的应用

致密油气已成为勘探热点。吐哈盆地温吉桑地区水西沟群发育多套致密砂岩,但含油气较好的相对优质储层厚度较薄,且横向变化快,加之上覆煤层影响及其本身低孔低渗的特点,导致相对优质储层与围岩的地球物理响应特征差异较小。常规储层预测方法及流体检测结果多解性强、精度低,很难满足该区致密砂岩勘探需要。利用地震、钻井、测井等信息,开展了主要反演井横波估算、弹性参数计算及模型正演、敏感参数分析,结果表明,该区含油气层顶表现为Ⅰ类AVO特征,λρ、Vp/Vs交会可以较好区分含油气砂岩。在此基础上,运用高品质三维地震资料,对温吉桑地区进行了AVO属性分析、叠前同时反演,并综合其他预测结果,对该区有利储层及含油气性进行了预测,在实际致密砂岩勘探中取得了较好应用效果。实践表明,叠前反演技术是目前储层预测、含油气检测的有效方法,极大地减少了常规储层反演的多解性。下一步将以这种技术手段为基础,应用于其他致密油气勘探工区。

The Application of Simultaneous Inversion of Prestack to Prediction of the Favorable Tight Oil and Gas Reservoirs in Tuha Basin

Tight oil and gas has become a hot topic in the exploration.There are few sets of tight sandstones in Shuixigou group in Wenjisang area of Tuba basin,but the reservoir thickness in relatively high quality oil and gas well is thin,and changes very fast in the lateral.Affected by the overlying coal bed and the charac- teristics of low porosity and low permeability of the reservoirs ,the characteristics of the geophysical response between the relatively high quality reservoirs and the wall rocks have little difference.The accuracy is very low in conventional prediction of the reservoirs and the testing results of the fluid ,which is difficult to meet the needs of the tight sandstone exploration in this area.Based on the information of seismic,well drilling and logging,the shear wave estimating and elastic parameters calculating and model forward and sensitive parame- ters analysis in the main inversion wells are carried out.The results show that the top of hydrocarbon bearing interval has the AVO characteristics of kind I , and λp and Vp/Vs intersection can better distinguish the oil and gas bearing sandstones.Based on this,3D seismic data with high quality is applied to the AVO attribute analysis and the simultaneous inversion of the prestack in the area of Wenjisang ,and the favorable reservoirs and oil-gas-bearing probability are predicted together with other prediction resuhs comprehensively.The effect of the application to the exploration of the tight sandstones is good.The practice shows that the prestack in- version is an effective method for reservoir prediction and oil-gas-bearing test now,which makes less solu- tions of the conventional reservoir inversion.Next this technology will provide the basis for the other tight hy- drocarbon in the next step of the exploration.