塔北中部地区奥陶系一间房组高电阻率地层成因及评价意义

Causes of high resistivity pay zone and evaluation significance for Yijianfang Formation of Ordovician in central Tabei area

塔里木盆地塔北隆起中部地区奥陶系一间房组底部普遍发育一套高电阻率地层,该层的测井曲线特征表现为伽马值较低、电阻率值较高、渗透率较低,与上下地层间存在较大差异,通常测井解释为致密层。沉积与储集层特征分析表明该特征地层的形成与成岩作用有关,研究认为一间房组滩体暴露,同生期岩溶地层水向下渗透,矿物溶出胶结形成致密层;同时该高电阻率地层可作为一个区域性隔层将上下两套储集层分隔,而且对油水分布具有一定控制作用。从生产特征来看上部储集层段普遍含油性较好,测试多为高产油气层;下部储集层由于多发育缝、洞,较上部储集性能更好,但油气充满程度低,由于上下整体压裂,导致措施井普遍高含水,此后建议单采其上部储集层,见到了好的效果,并为避免采取大型酸压措施后压串下套地层,制定了该地区生产井的完钻原则,即钻至高电阻率层完钻。该研究成果有效指导了该区的科研与生产,而且实施后取得了较好的经济效益。

At the bottom of Yijianfang Formation of Ordovician in central Tabei uplift in Tarim Basin,a set of high resistivity pay zone is commonly developed.For this high resistivity pay zone,well logging curves are characterized by lower gamma values,resistivity values and lower permeability,it is different from the upper and lower strata and usually interpreted as dense layer.The sedimentary and reservoir characteristics showed the formation of these characteristics were related to diagenese.By study,the beach body of Yijianfang Formation was found to be exposed,the syngenetic karst formation water penetrates down,the cementation of the mineral dissolution formed dense layer.This high resistivity formation can be used as a regional isolated interval to divide the upper and lower sets of reservoir,which has some control functions to oil and water distribution.Seen from the production characteristics,the hydrocarbon-bearing property of the upper reservoir beds is generally good,the well test proved the upper reservoirs are most high-yield oil and gas layers;due to the multi-developmental seams and holes,the reservoir performance of the lower reservoirs is better than that of the upper reservoirs,but its oil-gas filling degree is lower,since the upper and lower overall fracturing,it leads to stimulation wells generally high water cut,hereafter,the authors suggested that the upper reservoirs are single exploited,this productive method has achieved the good results,in order to avoid the large acid fracturing measures opening the upper formation,it also opened the lower strata,the completion principles of production wells of this area were worked out,that is,when drilling a high resistivity pay zone,the drilling is accomplished.The study results not only effectively guide the research and production of this area,but also have achieved better economic benefits after its implementation.