Risk Level Discrimination Model of Wells with Sustained Casing Pressure in HTHP and Sour Gas Contained Field

It is common that there are more and more wells with sustained casing pressure (SCP) in HTHP and sour gas contained field. It will result serious threats to the security of gas production. It is very important and imminent to determine the risk level of these wells to evaluate the well integrity. Based on international standards and reasons of well integrity failure, 30 parameters of gas well were put forward. They were divided to 3 categories, the characteristic, technological and the current state ones. And the influence of each parameter was evaluated respectively. Based on combination of field experience and theory research, single well score criterion and the model of evaluating well risk level were established. According to this model, the wells can be divided into 3 levels, well A, well B, and well C. Emergency measures are needed for well C. The characteristics and technologies parameters can determine the possibility and severity of well failure. The current state parameters are the most important ones to evaluate the well integrity. The annulus pressure and leaking rating can function as one-vote negation parameters. There is good agreement with the gas field. So there is some reference for the gas field.