川西坳陷致密砂岩气藏气体钻井条件下气测录井评价研究

Gas logging evaluation under gas drilling conditions in tight sandstone gas reservoirs in West Sichuan Depression.

针对气体钻井工艺条件下的气测录井存在气样采集与油气层评价难题,建议采用专业的气体钻井采集分离专利技术采集气样。在分析气体钻井与常规钻井对气测录井的影响因素和介绍气测定性解释评价法——全烃曲线形态法的基础上,通过对川西坳陷致密砂岩气藏气体钻井工艺条件下的气测录井资料、气水关系、地层压力及其相关性的分析,在排沙管线全烃值稳定状态下引入川西气井稳定试井中计算绝对无阻流量的公式,并在地层压力较大而井下流体流动压力较小可以忽略不计的条件下,对气测定量解释评价进行了深入研究,利用全烃和泵入气体排量计算天然气无阻流量(地层产气量)并以其为依据,初步形成了随钻对储气层进行相对定量评价与产能评估的方法。从该地区4口气体钻井施工井的测试井段来看,虽然该计算值与实际测试值有差别,但该计算方法可作为储气层评价的有效手段。

In view of gas sample acquisition and reservoir evaluation problems existed in gas logging under gas drilling conditions,the author recommended to use a professional gas drilling acquisition and separation patent technology to collect gas samples.Based on the analysis of impact factors of gas drilling and conventional drilling on gas logging and the presentation of gas logging qualitative interpretation and evaluation method-total hydrocarbon curve shape,through the analysis for gas logging data,gas and water relations,formation pressure and their correlation analysis under gas drilling conditions for the tight sandstone gas reservoirs in West Sichuan Depression,the paper introduced a formula to calculate the absolute open flow for Western Sichuan steady gas well testing under steady total hydrocarbon value at sand discharging pipelines,under the condition of greater formation pressure and less downhole fluid flow pressure which can be negligible,the author carried out a deep study on gas quantitative interpretation and evaluation.By the use of total hydrocarbon and pump-in gas flow rate to calculate open flow potential(formation gas production)and be based upon it,the initial relative quantitative evaluation and capacity evaluation methods were formed for gas reservoirs while drilling.Seen from the test intervals of the area′s four wells,although the calculated values and the actual test values are different,the calculation method can be used as an effective means to evaluate gas reservoirs.