Reliable and economical selection for casing pipe in low-potential gas field

Reliable and economical selection of casing pipe in development of low-potential gas field is one of efficient measurements to reduce development cost.The main influence factors are specified by application evaluation test of API long round thread casing pipe.With actual working conditions and mainstream well structure of low-potential Sulige gas field,according to statistical results of experimental data for casing historical goods,the safety coefficient of string casing design is determined by reliability analysis methods,reliable effect of load variability on casing pipe is checked,and two string plans is designed successfully.They are ?139.7mm×7.72/9.17 mm N80/J55 LC+CATTS101 special thread compound casing string and ?139.7 mm×9.17 mm N80 LC+CATTS101 special thread casing string.Casing thread parameter controls collar out-of-roundness under 0.7% by standoff and pitch.Optimum and maximum torque is used for threading and interference coils are not less than 1.70 coils.CATTS101 thread compounds are used for threading,which should have uniform and appropriate painting.According to various factors influencing casing pipe suitability,additional technical specification for casing order and field operation specification are established.As a result,more than 160 wells,taking the said measurements,have good performance and make remarkable economic benefit.