The Analysis Of Blasting And Burning Of Air Atomized Drilling Well

Fire in the bottom of a well is one of the notable problems of air drilling or air atomized drilling. Fire blast will happen when air meets with any oil pool,and the consequent loss will be quite serious. Fire problem limits air atomized drilling practice into a small scale and makes this low cost drilling technology with high speed can't be used widely resulting in uncountable indirect loss. Theoretic analysis in fire blast in well becomes very complex because of the following uncertainties caused by the complexity of wells:Oil pool's position,output,composition and the pressure and temperature distributions of the well circle system.Temperature and position of abnormal high temperature thermal sources.Spark induced by the hitting inter drill and rock crumbles or inter rock crumbles.Other uncertain factors.International studies regarding fires in the bottom of wells is very rough,and fire protection methods are few and incomplete. The practical way is still to avoid adopting air drilling in the oil pool.According to the documentation and information,research in fire blast in the bottom of wells is described as following:What is the most important is to find combustible gases on time and once the gases appear,substitutes moisture gas will helpful. But the best way is to use natural gas or nitrogen drilling. Using fire stop or manual manage to shut down the air source can prevent and extinct fire quickly. It was used to advise to substitute natural gas when drilling oil pool. But this impractical because gas sources were far and the cost was high. Fire stop can't manage the problem of fire blast protection in well,but only to extinct fire when combustion is continue. U.S. A and Canada began to use inert gases drilling in order to realize low harm drilling. At the very beginning,liquid nitrogen was used,later,mixture of nitrogen and air. At the end of 1993,the membrane separate device system was introduced in drilling to afford nitrogen. This "huge" expensive device with short life-span was not popular,used mostly in filling liquid gas drilling and bubble drilling or other lower consume gas conditions.The paper analyzes fire blast problem of the bottom of wells fitted with experiment,and finds the theoretic base of inert gases drilling affording reliable theory proof for using inert gases drilling technology. The flammable limit border is analyzed and mathematical model is built up and solved under the conditions of auto-ignition,thermal source ignition and spark ignition of mixture of air and combustible gas. The popular current fire protection views are analyzed and a new point is proposed regarding practical drilling engineering. The experimental result fitting to the simulate result proves that the measure and test of the experiment system are accurate and reliable enough to carry out experiment correctly. The experiment result agrees well with the theoretical calculating result under high pressure and high temperature condition,and satisfies the requirement of engineering calculation. It proves that this fire combustion program design of fire protection and extinction is correct. The .design has a certain value in practice.