物质平衡法在气体钻井中的应用研究

APPLICATION OF MATERIAL BALANCE METHOD IN GAS DRILLING

空气钻井可以大幅度地提高钻井速度,最大程度地保护和发现储层,已经逐渐成为国内外钻井界研究应用的热点新技术之一。但是,一个具体的气藏能否开展气体钻井,将受到地层压力的严格限制。异常高压气藏经过长时间开采后,地层压力通常会有大幅度的下降,有可能满足气体钻井需要。为此,以物质平衡法为基础,建立了计算异常高压气藏地层压力的新方法,并根据工程实际需要进行简化,得出了简便、易于操作的计算公式。对川西地区主力气藏目前的地层压力进行了预测,对该方法在实际应用中可能遇到的问题也进行了讨论,给出了相应的建议。该预测方法简单、快捷,不需要进行试井测试和复杂的试井解释,计算精度能够满足实际气体钻井工程设计的要求。

Air drilling can largely improve the drilling speed,protect and discover the pay zones to the greatest extent.It is becoming a research and application hotspot in drilling industry both at home and abroad.However,whether a gas reservoir can be developed by gas drilling technology or not is strictly limited by formation pressure.As for the abnormally high pressure gas reservoirs the formation pressure will often decrease remarkably after long period of development,so the gas drilling technology can be adopted.Herein a new method calculating the formation pressure of abnormally high pressure gas reservoir is established based on the material balance method.After combining the actual engineering conditions,this method is simplified into easy and practical calculation formulae.By being used to predict the current formation pressure of major gas reservoir in west Sichuan area,the problems tending to occur during application are discussed,and corresponding suggestion provided.This prediction method set up herein is simple and quick to get results,and no need to conduct well testing and complicated interpretation.Its accuracy can meet the requirements of gas drilling design.