Natural Gas Underbalanced Drilling Technology And Its Applied Research, Gas Fields In Shunan

Aiming at the explorative/exploitive difficult problem of reservoir's low pressure and low permeation in south SiChuan, and according to the geologic characters of south SiChuan reservoir we have developed the research of natural gas under-balanced drilling technology in south SiChuan gas reservoir. This article started from the gas reservoir's character in south SiChuan, studied the gas reservoir damage principle and protection measures of the XuJia river stratum qualitative analysed the reservoir damage that during the balanced drilling the drilling fluid, complete drilling fluid caused to and put forward the protection measures of the XuJia river stratum. On the base of the relative achievements of under-balanced drilling in foreign countries and annular space carry drillings theory, we used multi-phase flow theory and method, set up the theoretic annular space flow of natural gas under-balanced drilling, and solved the model by making use of mathematical method, analysed the pressure distribution, Speed distribution, the carrying drillings ability of fluid and returning pressure effect by using the mathematical stimulating software of under-balanced drilling, then determined the right drilling parameters of gas under-balanced drilling. We have analysed the affect rules of the parameters controlling the drilling course and have researched the parameters during the water lifting mixed with gas. We also have researched the safe drilling technology of gas under-balanced drilling, put forward the equipment program on the surface and put forward the equipment program on the surface and technological progress of gas under-balanced drilling, and arranged to compile safe drilling rules of gas under-balanced drilling. By using the research achievements , we have developed many experiment research at the drilling areas , such as JingQian well 2,MaQian well 1 and BaoQian well 4 and have got technologic and economic benefit very well. By doing such we formed preliminarily the gas under-balanced drilling technology witch was applicable to the low pressure and low permeation reservoir in south SiChuan, which is expected to realize the gas under-balanced drilling technology can be applied industrially south SiChuan areas.