Staged Diverting Acid Fracturing in Horizontal Wells
In view of the problems occurred in the traditional acid fracturing of the Lower Paleozoic carbonate reservoir of the Daniudi gas field such as poor control of acid filtration loss,fast reaction between rock and acid and short etching distance,a trial test was made in the Ordovician Majiagou Formation reservoir through multi-stage external packers in horizontal wells by use of staged diversion acid fracturing. It is shown from the practical application that a viscosity difference is formed between the spent acid left after acid / rock reaction and the fresh acid,which works well in lowering filtration and diverting acid. The acid fracturing string has an integrated structure,including acid fracturing and production combined string + open hole packer + fracturing slide sleeve,realizing an integrated job by one trip to accomplish staged open hole completion,staged acid fracturing,liquid displacement and production start-up,a high yield gas stream was delivered at an OFP of 5. 92 × 104m3/d.