南海深水区气井产能评价新方法

A new method to predict the productivity of gas wells in deepwaters of the South China Sea

为了解决中国南海深水气田探井、评价井产能测试成本高、测试井少、产能资料稀缺所导致的产能预测准确度不够高的难题,以南海深水区LS气田为研究对象,分析了深水气井产能主控因素,提出了流体因子和压力因子两个表征流体性质的参数,基于气井产能方程构建了深水气田产能评价公式,定义了气井产能因子参数,基于产能因子和有效渗透率的关系建立了南海深水区LS气田产能评价新图版,进而提出了一种深水未测试气井产能预测新方法。研究结果表明:①LS气田弱非均质性储层有效渗透率与非均质性具有较好的规律性;②LS气田流体因子与压力因子呈现出较好的线性关系;③产能因子和有效渗透率拟合相关性好,可以基于产能因子和有效渗透率的关系构建南海深水区LS气田产能评价新图版。结论认为:①通过LSX-W1井应用验证,新方法预测的天然气无阻流量与DST测试得到的无阻流量误差仅为10%,说明该方法具有较高的预测精度,可以满足矿场应用的要求;②新方法可以通过常规的测井、测压方法,无需DST测试就可以进行深水气田未测试井的产能评价,可以大幅度节约深水井勘探测试费用,可以为深水气田大规模勘探提供支撑。

For most of exploration and evaluation wells in deepwater gasfields of the South China Sea,high cost in productivity test,few test wells,and shortage of productivity data bring about some challenges in uncertain productivity test.So,the main factors controlling the productivity of deepwater wells were analyzed by taking LS gasfield in deepwaters of the South China Sea as an objective.And then,two parameters on fluid-property char⁃acterization,including fluid factor and pressure factor,were proposed.In addition,based on one empirical produc⁃tivity formula,another productivity evaluation formula was built up to define the productivity factor,and a new productivity evaluation chart was also developed according to the relationship of productivity factor to effective permeability.Finally,a new method to predict the productivity of untested deepwater gas wells was put forward.Results show that in LS gasfield,(1)both effective permeability and heterogeneity in poorly heterogeneous reser⁃voirs present better regularity;(2)there is a better linear relation between fluid factor and pressure factor;and(3)with the productivity factor and effective permeability as soul,the new productivity evaluation chart has good correlation.In conclusion,after this new method is used to predict the productivity of LSX-W1 well,the error between predicted open flow and another open flow from DST is only 10%,showing a higher accuracy in this prediction.Furthermore,with its help,the productivity of untested wells in deepwater gasfields can be evaluated by using conventional well logging and pressure test even without DST.As a result,the exploration and test cost in deepwater wells may be reduced greatly,so as to provide effective support for their extensive explora⁃tion.