延长下古生界白云岩储层酸压工艺技术室内研究

Indoor Research of Acid Fracturing Technology in Dolomite Reservoir of Lower Paleozoic Era of Yanchang Gas Field

延长下古生界白云岩气层是奥陶系马家沟组经长期岩溶风化形成的白云岩储层,目前多采用稠化酸闭合酸压工艺技术进行开发,酸压效果整体上不理想。动静态酸岩反应实验发现,主力层段天然裂缝发育非均质性较强,多级酸压工艺、转向酸酸压工艺或多氢酸酸压工艺也具有很大的不确定性。为解决这一问题,开展了白云岩储层动静态酸岩反应室内实验研究。根据白云岩储层的动静态酸岩反应情况及岩心表面酸溶蚀形态宏观与微观特征及其与物性、注入排量和注入压力的关系,发现储层中良好的酸蚀形态多分布于裂缝、溶洞周围,具有很强的非均匀性,稠化酸酸液优于普通酸液。在储层地质特征研究和室内实验的基础上提出适用性较强的稠化酸二次增黏工艺、变黏酸压工艺,低黏酸缝网酸压工艺技术等多种新型酸压工艺技术措施,对本区域的白云岩储层整体酸压开发实践具有很好的指导意义。

The dolomite reservoir of Yanchang lower paleozoic era is an dolomite reservoir formed by long-term karst weath- ering in Majiagou Formation of Ordovician, At present, thickening acid closed acid fracturing technology is usually applied to develop it, and the acid fracturing effect on the whole is not ideal. Static and dynamic acid rock response experiment found that the main interval natural fractures have strong heterogeneity, and the multi-stage acid fracturing technology, turning sour sour compression technology or hydrogen pressure technology have also great uncertainty. To solve this prob- lem, the indoor research of static and dynamic acid rock response in dolomite reservoir is carried out. According to the dy- namic acid rock response in dolomite reservoir, the macroscopic and microscopic characteristics of core surface acid disso- lution morphology, and the relationship between physical properties, injection rate and injection pressure and them, we found that the nice acid dissolution morphology is usually distributed around the cracks and caves, with strong heterogenei- ty, and its thickened sour liquid better than ordinary acid. On the basis of the reservoir geological features research and in- door tests, we put forward a variety of new acid fracturing technology measures with strong applicability, such as thickening acid secondary thickening process, viscosity conversion acid fracturing technology, low viscosity acid seam net acid fractu- ring technology and so on, which has the very good guidance significance for the breakthrough of overall acid fracturing de- velopment practices in dolomite reservoir of this area.