Chapter Seven - Gas Drilling Operations

Abstract

This chapter introduces operating procedures in gas drilling to reduce operation complications and outlined measures to avoid gas drilling problems. Special procedures are followed in gas drilling to ensure smooth operations. These include initiating gas drilling, initiating mist drilling, making connections, and tripping pipe. Owing to the low density of gas, wellbore pressures are much lower in gas drilling than in conventional drilling operations. Lack of support of fluids to the borehole frequently causes wellbore instability, often resulting in boreholes caving in, collapsing, or getting narrower. Among many chemicals, KCl is widely used for controlling clay swelling. Anionic surfactants or household detergents are often used as foaming agents to form foam in the annulus so the inhibiting solution can be brought up to the intervals where water-sensitive clays exist. Although the gas density is relatively high at this point compared to the upper hole section, the kinetic energy of gas at this point is the lowest.