Acid fracturing technology for thick fractured sandstone reservoir of deep wells with abnormal high pressure

The pay formation of Kuqa foreland thrust belt in Tarim Oilfield is features in high formation pressure and natural fracture developed here. Lots of drilling fluid often leaked off into the formation during drilling. The experiment of core fracture initiation and core flow shows that the conventional matrix acidizing could not effectively remove the damage, so the acid fracturing technology which could open the natural fractures is required to be applied. Meanwhile, in view of the requirement of reasonable acidification of long hole sections, the temporary acidizing mechanism is derived. It is pointed out that increasing the viscosity of temporary acidizing fluid is useful to reasonable acidification. Then a new technology combining acidizing with sandstone acid fracturing for fractured sandstone reservoir of high pressure is proposed. Through the application to KS2 well, the technology is proved to have high adaptability and remarkable stimulation effect. It could be valuable reference to stimulation and alteration of similar reservoirs.