气体钻井注气量计算方法研究进展

气体钻井过程所需注气量是关系到气体钻井成败的重要参数。目前计算气体钻井所需注气量的3种方法各有不足,根据这些方法得出的计算结果与现实情况都有差异,有时差异还很大。为了准确计算气体钻井所需注气量,应对影响气体钻井注气量的因素进行深入研究并对现有计算方法进行改进。经过对现有方法的分析,建议应从以下几个方面进行深入研究：①建立准确计算气体钻井时环空流体温度的模型以确定温度对注气量的影响;②应用气液两相流理论分析气体携水能力,以确定地层出水时气体钻井所需注气量;③钻屑直径对气体钻井所需注气量的影响;④气体钻井所需注气量与井斜角的关系;⑤对“关键点”处钻具外形进行优化设计以改善该处气体的携岩能力。

STUDY ADVANCES IN GAS VOLUME REQUIREMENT CALCULATION FOR GAS DRILLING

The gas volume required for gas drilling is an important parameter critical to the success of gas drilling. Those three gas requirement calculation methods presently used all have shortcomings. The results calculated by these methods cannot reflect the real situations; sometimes the difference is very great. In order to calculate the gas volume requirement accurately, an in depth study on factors affecting the gas requirement of gas drilling is necessary, so as to improve the existing calculation methods. Based on the analysis of the currently used methods, it is suggested that study be performed on following issues: ①to set up an annulus fluid temperature model to determine the effects of temperature on gas volume requirement; ②to use gas/liquid two phase fluid theory to analyze the water carrying capability of the gas, so as to determine the gas volume requirement when there is water production from the formation; ③to determine the effects of cuttings size on gas volume requirement; ④to find the relationship between the gas volume requirement and the inclination; ⑤to optimize the external geometry of the BHA at the "key point", and in the end to improve the cuttings carrying capability of the gas.