A New Method for Determining Abandonment Formation Pressure in Sulige Gas Field

Abandonment formation pressure is a key parameter for gas recovery calculation. The natural productivity of Sulige tight sandstone gas reservoir is low which requires fracturing to obtain industrial gas flow. Existing calculation methods of abandonment pressure did not consider reservoir reformation and stress sensitivity which may result in calculating error. Based on seepage mechanism of tight reservoir, a new method taking the starting pressure gradient and reservoir stress sensitivity into account to calculate the pressure of abandonment formation in fractured gas wells was established. The new method also analyzed the effects of factors including fracture half-length, starting pressure gradient, and stress sensitivity coefficient on the abandonment pressure. The results indicated that the starting pressure gradient and sensitivity coefficient have a greater impact on abandonment pressure. The abandonment pressure in different types of wells were significantly different, the abandonment pressure of type I, II, III wells were 3.12 MPa, 7.13 MPa and 10.27 MPa respectively, which can better explain the high gas pressure and low production phenomenon in some gas wells in Sulige gas field and provide technical guidance for the development of gas field development plans.