裂缝性致密油藏润湿性提高采收率技术研究

在裂缝性致密储层中,水驱效率往往由水自发吸入含原油基质块控制。当基质是原油润湿或中性润湿时,原油很难通过自发渗吸采出。研究目的是确定可以添加到注入水并提高深吸效率的表活剂组合。通过评价几种表活剂在储层温度和矿化度下的水稳定性并在富含粘土的砂岩上测量接触角,对储层岩心进行渗吸试验。结果表明使用一定浓度的表活剂溶液可实现矿物板的润湿反转。之后通过在致密油湿或中性润湿砂岩岩心上进行的自发吸入试验获得较润湿反转前68%的渗吸增量。同时数值模拟的研究也证实随着润湿性的变化,原油回收率也发生明显改变,且与断裂密度和原油粘度相关。

Study on EOR With Alteration of Rock Wettability in Fractured Tight Reservoirs

In fractured tight reservoirs, the water flooding efficiency is often controlled by the spontaneous absorption of water containing crude oil matrix. When the substrate is wet or neutral wetting of crude oil, it is difficult for crude oil to be produced by spontaneous imbibition. The purpose of this study is to determine the surfactant combination that can be added to the injected water to improve deep absorption efficiency. The water stability of several surfactant in reservoir temperature and salinity was evaluated, and the contact angle was measured on clay rich sandstone, and imbibition test of reservoir core was carried out. The results showed that the wettability reversal of mineral plates was achieved by using a certain amount of surfactant solution. Afterwards, imbibition increment of 68％ before wetting reversal was obtained by spontaneous imbibition test on dense oil wetted or neutral wetted sandstone cores. The results of numerical simulation showed that the recovery rate of crude oil significantly varied with the wettability, and was related to fracture density and viscosity of crude oil.