前置酸压裂工艺在姬塬油田延长组老井油层改造中应用

Application of prepositioned acid fracturing in reservoir improvement in Yanchang group of Jiyuan Oilfield

姬塬油田属特低渗透性油田,储层渗透率低,由储层基质向裂缝壁面的渗流能力差。在油层改造中虽然采取了多种酸化、压裂增产措施,但措施效果不理想,产能恢复慢,有效期短,很难达到预期的增产效果。前置酸压裂多缝体积改造技术在老井油层改造中可实现对近井地层、裂缝壁面、远端裂缝周围地层进行深部解堵处理,且在大排量挤酸的过程中通过溶蚀作用可以开启地层微裂缝,形成新的产油通道。挤酸关井反应后对储层压裂改造,在扩大裂缝规模的同时,将酸溶蚀开启的微裂缝填砂延伸,实现对油层的体积改造目标,并取得了比较好的增产效果。

Jiyuan oilfield as an ultra-low permeability oilfield features low permeability and seepage ability of substratum to fracture surface,which leads to the low efficiency of acidification and fracturing measures in improving the output,such as slow capacity recovery and short validity.Prepositioned acid fracturing is developed to break down the blocking in old wells reservoir with respect to the near wellbore formation,fracture surface and formations surrounding the far fractures.It can open formation micro cracks during the large displacement of acid squeezing by dissolution and form new oil channel.After acid squeeze shut-in reaction the reservoir fracturing is modified by enlarging the scale of fracture and filling sand in the micro-fractures to improve the volume and output of the reservoir.