Based on a systematic analysis of gas accumulation mechanism and its main constraints together with the background and origin of overpressure in Yinggehai basin, it can be shown that the abnormal pressure is the major driver of gas migration, and that the natural hydrofracturing has produced vertical paths for gas migration.

According to the main effect parameters of hydrofracturing,the episodic compaction stage includes hydraulic fracture and hyd.

Based on 3-dimensional hydraulic fracturing model and the similarities between fluid flow in limited entry fracturing process and electricity current flow in circulation circuit,a numerical model was developed to compute the injection reallocation rates in different layers.

Single well zonal earth stress and rock mechanic parameters are calculated for limited entry fracturing in Well Bin670 and for determination of the extreme injection pressure in block Bin660-665.

In order to solve this problem,a research of limited entry fracturing technology for horizontal wells has been fulfilled,and a successful field experiment of fracturing and associate techniques was done in Well Niuping 10-12,in which 4 perforated intervals were stimulated in large scale,the initial flow rate of the well after fracturing was 7.