大港油田南部滩海区沙一下亚段碳酸盐岩储集层特征

Carbonate reservoir features of Sha 1 under-sub interval in south beach region of Dagang Oilfield

大港油田南部滩海区发育的沙一下亚段湖泊相半深湖亚相泥云灰坪和云灰坪微相区的碳酸盐岩储集层是油气勘探开发的有利区域。该套碳酸盐岩储集层具有纵向非均质性较强,横向尚可连续对比的特点,由于其不是较纯的碳酸盐岩层,而是成分较复杂的由碳酸盐岩、泥质、砂质组成的含泥含砂灰岩或含灰含云砂质泥岩,宜归属于复杂岩性储集层。储集层孔隙类型主要是长石、方解石、白云岩局部溶解形成的次生孔以及微裂隙,储集层物性较差,孔隙度一般为2%～8%,渗透率一般在0.1～2 mD之间,属于特低孔隙度、特低渗透率储集层,综合评价其为差的储集层,必须实施人工增产措施后才可获得高产的油气流。这套碳酸盐岩储集层酸敏程度为中等偏强—极强,酸化后渗透率有所下降,从而对增产开发工艺技术的优选提出预示。

Carbonate reservoir of Sha 1 under-sub interval in south beach region of Dagang Oilfield is the favorable region for oil and gas exploration and development.This set of carbonate reservoir has the features of stronger longitudinal heterogeneity and horizontal continuous contrast,which is not the pure carbonate layer,but is a layer of mud-bearing arenaceous limestone or ash-laden arenaceous mud stone, consisting of complex carbonate,argiloid,arenaceous rock, and so belongs to the reservoir of the complex lithology. The dominant pore types in the reservoir are secondary pores and micro fractures formed by partial dissolved feld- spar,calcite and dolomite,physical properties are poorer, common porosity is 2% to 8%,permeability is between 0.1 to 2 mD,and it belongs to very low porosity and very low permeability reservoir.In conclusion,it is a poor reservoir in which higher oil and gas stream can only be obtained by conducting artificial production increasing measures.The acid sensitive grade in this set of carbonate reservoir is me- dium stronger to very strong,the permeability decreases af- ter acidizing,which provides the optimum prediction for production increasing technology.