An Explosive Range Model Based on the Gas Composition, Temperature, and Pressure during Air Drilling

Abstract EN

Air drilling is low cost and effectively improves the penetration rate and causes minimal damage to liquid-sensitive pay zones.

However, there is a potential downhole explosion when combustible gas mixed with drilling fluid reaches the combustible condition.

In this paper, based on the underground combustion mechanism, an explosive range calculation model is established.

This model couples the state equation and the empirical formula method, which considers the inert gas content, pressure, mixed gas component, and temperature.

The result shows that increase of the inert gas content narrows the explosive range, while increase of the gas temperature and pressure improves the explosive range.

A case in Chongqing, China, is used to validate the explosive range calculation model.