鄂尔多斯盆地L区块石盒子组4段致密砂岩气藏地质-工程甜点预测与评价

Prediction and evaluation on geological and engineering sweet spots:Examples from H4 tight sandstone reservoirs,L block,Ordos Basin

鄂尔多斯盆地L区块为致密砂岩气藏,天然气资源量大,但存在储层物性差、气水识别难、砂体分布复杂、非均质性强等问题,制约了本区致密气藏的勘探开发。为此,从地质工程一体化研究思路出发,结合岩心资料、钻井资料、地震资料和区域地质背景等基础资料,采用地质统计学反演进行储层砂体预测,利用协克里金算法预测储层孔隙度分布,利用地震高频衰减的算法预测含气性分布,通过多参数融合得到地质甜点有利区。利用地震蚂蚁体算法预测储层裂缝发育状况,利用地震叠前弹性反演得到脆性指数分布,进而判断储层可压性,由此得到工程甜点有利区。研究表明利用地质与工程“双甜点”综合预测方法,圈定储层有利区,在井位部署以及压裂改造井层筛选中起到了重要的作用。

Rich natural-gas resources have been found in tight sandstone reservoirs,L block,Ordos Basin,however,which are featured by poor physical properties,difficulty in identifying gas and water layers,complex sandstone distribution,and strong heterogeneity,bringing about challenges in their exploration and development.So,based on one idea of geology integrating with engineering,the reservoir sandboby was predicted by means of geostatistical inversion according to a lot of core,drilling,seismic,and regional geological data.And then,the porosity distribution and gas-bearing property were respectively predicted by the Kriging algorithm and high-frequency attenuation algorithm to achieve geological sweet spots through multi-parameter fusion.Finally,the fracture development in these reservoirs was predicted by the ant-body algorithm and the distribution of brittleness index was gained from the prestack elastic inversion to identify the fracturability,and consequently engineering sweet spots were obtained.Results show that the method to predict the geological and engineering"dual sweet spots"can effectively delineate favorable reservoirs and play an important role in well deployment and target selected for fracturing stimulation.