超低渗透油藏大斜度井适应性评价

Adaptability evaluation of highly deviated well in ultra-low permeability reservoirs

鄂尔多斯盆地三叠系延长组发育内陆湖泊-三角洲碎屑沉积体系,轻质油储量丰富,开采潜力巨大。同时,由于纵向沉积的多旋回性和横向沉积相带的变化,储层隔夹层发育,体积压裂缝网难以实现层间有效连通。大斜度井井身特征兼具直井与水平井的特点,是适用于多层系储层高效开发的新式井型。现阶段大斜度井体积压裂适应性及生产动态特征的研究较少,文中考虑储层厚度及稳定隔夹层发育状况,将目标区块储层划分为厚油层、薄油层、薄互层3种地质模式,借助油藏数值模拟,对比水平井、直井评价了大斜度井在不同地质模式下的适应性,分析了储层渗透率及层间非均质性等因素的影响。研究表明:大斜度井适用于开发薄油层Ⅰ类,薄互层Ⅰ类、Ⅱ类以及厚油层Ⅰ类、Ⅱ类储层,同时当薄互层储层层间非均质性强、主力层突出时,可考虑非主力层暂不开发,优先采用水平井开发主力层。

The Triassic Yanchang Formation in Ordos Basin developed an inland lacustrine-delta clastic sedimentary system with abundant light oil reserves and large exploitation potential.Due to the multicycle of vertical deposition,change of lateral sedimentary facies and developed reservoir interlayers,it is difficult for the volume fracturing network to connect different layers.Well bore of highly deviated wells have the characteristics of both horizontal wells and directional wells,which are suitable for the efficient development of multi-layer reservoirs.At present,there are few research on the adaptability and production performance of highly deviated wells with volume fracturing.In this paper,considering the development of longitudinal reservoir interlayer,three geological models of thick oil layer,thin oil layer and thin interbed are proposed from the target block.With the help of reservoir numerical simulation,the adaptability of highly deviated wells in different geological models is evaluated by comparing horizontal wells and directional wells,and the influence of the reservoir permeability and the longitudinal heterogeneity are analyzed.The research shows that highly deviated wells are suitable for thin oil layer typeⅠ,thin interbed typeⅠ,Ⅱand thick oil layer typeⅠ,Ⅱreservoirs.At the same time,when the longitudinal heterogeneity of thin interbed reservoir is serious and main reservoir is obvious,the policy of non-main reservoir not developing temporarily and priority to the development of horizontal wells in main reservoir can be considered.