自然电位测井在低阻油气层识别中的应用——以塔里木盆地吉拉克地区三叠系低阻油气层为例

Application of spontaneous potential logging to the identification of low resistivity reservoirs —an example from the Triassic reservoirs in Jilake area of the Tarim Basin

赵军，王淼，闫爽，李华纬

摘要：由于低阻油气层电阻率和水层电阻率接近，给应用常规测井资料识别低阻油气层油水层、确定油水界面位置带来了困难。对低阻层和非低阻层样品进行的完全含水电导率（Co）和溶液电导率（Cw）关系的实验证实，在低阻层由于粘土矿物附加导电作用是形成吉拉克地区三叠系第二油组低阻的主要原因。研究表明，该类低电阻油层被钻穿后，粘土表面阴离子将吸附溶液中的阳离子，被吸附到粘土矿物表面的阳离子又会进一步牵制溶液中阴离子的迁移，使低阻油气层内出现离子滞留现象，形成电荷屏蔽。造成低阻油气层段自然电位测井曲线与非低阻层相比，负差异下降，通过建立一条非低阻状态下的拟自然电位曲线SPrt，将其与SP曲线进行对比，根据叠合特征可识别低阻油气层。实际资料应用表明，该方法在吉拉克地区应用效果明显，能较好地识别低电阻油气层。

Abstract: As low resistivity reservoirs have similar resistivity as water layers, it is difficult to differentiate water layers from low resistivity reservoirs, and to determine oilwater contacts by using conventional logging data. Experimental study on relationship between full waterbearing conductivity (Co) and solution conductivity (Cw) with samples from lowresistivity layers and nonlowresistivity layers shows that the additional conductivity contributed by clay minerals is the main factor leading to the low resistivity of the second unit of the Triassic in Jilake area. When this type of lowresistivity reservoirs is penetrated, anions on clay surface may absorb cations in the solution. The cations absorbed to clay surface in turn may further impede the migration of anions in the solution, resulting in ion retention in the low resistivity reservoirs and charge shielding. The negative difference of SP log of the lowresistivity layers decreases in comparison with the nonlowresistivity layers. A quasispontaneous curve (SPrt) of nonlowresistivity layers is then created and compared with the SP curve to identify lowresistivity layers. This method has been successfully applied to recognize the lowresistivity reservoirs in the study area.

10.11743/ogg20110212