OPTIMIZATION OF TECHNOLOGICAL SOLUTIONS FOR THE CONSTRUCTION OF WELLS FOR LOW-PRESSURE GAS PRODUCTION

The relevance of the research is caused by the necessity to apply the geomechanical modeling to substantiate the possibility for exploitation of low-pressure layers of the Cenomanian complex of the West Siberian oil and gas province with drilling liquids with density of 0,6 g/cm3 and to increase the profitability of drilling by constructing small-diameter wells. The main aims: colection of information necessary for geomechanical modeling; construction of a mathematical model of the mechanical properties of rocks composing the drilling interval for the production string; correlation analysis of calculated values and values obtained during core tests; correction of the model of mechanical properties based on experimental data; determination of boundary conditions for destabilization of the walls of wells under the influence of multidirectional effective stresses; establishing a safe interval of drilling mud density for exploitation low-pressure reservoirs; justification of the possibility of using washing liquids with density of 0,5-0,8 g/cm3; calculation of the strength characteristics of the well support, taking into account the reduction of its metal consumption; conducting economic justification of the feasibility of using small-diameter wells for field development at a late stage. Objects: lightweight drilling fluids, depression drilling technology, small-diameter wells. Methods: geomechanical modeling of the strength properties of rocks composing the geological section of wells for the production of lowpressure gas of the Cenomanian deposit; calculation of casing strings for strength at various stages of operation. Results. The authors have constructed the mathematical model of the elastic-strength properties of rocks of the drilling interval for the production string and determined the stress values at which the walls begin to fall out. They substantiated the possibility of drilling lowpressure wells using drilling fluids with density of 0,6 g/cm3, taking into account the prevention of fallings and colapses of the walls of wells and proved the possibility of reducing the metal consumption of the design of low-pressure wells to increase economic efficiency of drilling.