Study and application of drilling techniques in Xiwang Oilfield

Because the complicated formations（such as mudstone, salt bed and gypsolyte）are drilled in Xiwang Oilfield, three-section casing is usually taken as the well structure of exploration wells, but the drilling cost is high, and the drilling period is long. The drilling technique of development wells is determined to be used to decrease drilling cost and to speed up the pace of productivity construction. The advantages of the well are normal formation pressure and high formation fracture pressure gradient, but two problems must been resolved which are wall stabilization of mudstone, salt bed and gypsolyte and formation damage control. To ensure wall stabilization, zwitterionic polymer drilling fluid is selected and macromolecule polymer must been maintained at reasonable value. the technique of temporary shielded plugging is applied to protect the two formations. Therefore, the drilling technique of development wells is formed by combining the optimization technique of well structure with drilling fluid technique, and well structure may be optimized from three-section casing to two-section casing. The results of the field application of the technique show that the drilling operation is smooth, the drilling period is shortened, the drilling cost is reduced, the productivity is high, and the economical and social benefit are apparent.