致密砂岩储层酸化体系研究—以迪北气藏为例

迪北气藏为典型的致密砂岩储层,该储层低孔低渗、孔隙间连通性差,同时具有强烈的酸敏损害,常规酸化无法有效的改善储层物性。在实验室内针对其损害机理的研究,研制出了适用于该致密砂岩储层的复合酸,该酸液在扩大孔隙间渗流通道的同时针对其砂岩储层中大量绿泥石中Fe2+遇酸沉淀起到良好的抑制作用;在岩芯流动实验中,对不同渗透率的致密砂岩岩芯,分别提高其渗透率2.9倍、4.7倍;通过对酸处理过的岩芯进行观察,该酸液在解除损害的同时对岩芯骨架结构破坏较小,且端面相对完整,可保证近井壁岩石的稳定。

Research on Acidification System of Tight Sandstone Reservoirs——Taking Dibei Gas Reservoir as a Study Case

Dibei gas reservoir is a typical tight sandstone reservoir with low porosity,low permeability,poor connectivity between the pores,and it has strong acid sensitivity damage,conventional acidification cannot effectively improve reservoir properties.The damage mechanism was studied in the laboratory,a set of compound acid system applicable to tight sandstone reservoirs was developed.The acid can expand the flow channel between the pores,at the same time,it can inhibit the precipitation formed by the reaction between acid and Fe2+ from a large amount of chlorite in sandstone reservoirs.In the core flow experiment,the permeabilities of different tight sandstone cores were increased 2.9 times and 4.7 times.Acid-treated core was observed,the acid liquid relieved the damage,while core skeleton structural damage was small and end faces were relatively complete,which could guarantee the stability of the rock near the wellbore.