中国天然气统计预测中的若干问题探讨

Issues in statistical work and forecast of natural gas resources in China

天然气由地下资源变成商品经历了复杂的过程,涉及许多术语概念,容易产生混淆,有可能会影响到对天然气的统计、预测和深入研究,为此对中国天然气统计预测中的若干问题进行了探讨。结果认为:①地下天然气以气层气和溶解气(石油伴生气)形式赋存,前者的产量在我国近期迅速增长,而后者的产量则呈下降趋势,在预测未来指标时决不能将其混为一谈;②致密气在美国属于非常规天然气,而我国却将其纳入常规气产量,因此在讨论非常规气占天然气产量比例、页岩气占非常规气比例时不能将两国间的数字仅作简单对比;③地面钻井采出的煤层气和矿井井下抽采的煤层气(煤矿瓦斯)在产量控制因素、成分和利用率上均存在着重大差别,须分别统计并预测其未来产量;④在未作初步普查勘探前,尚无能反映研究区各层系地下一定深度含气性和可采性的基础性参数,这时对其天然气资源潜力评估所得数字的可靠性甚差,对此应有清醒的认识;⑤页岩气虽具大面积分布的特点,但其勘探开发仍要经历普查选区面中求点逐步发展的程序,要经历逐步认识中国页岩气特点适应中国特殊的外部环境的过程,在起步阶段不宜有过高的发展指标;⑥天然气井口产量、管线进口门站和LNG接收站的输入量与可供用户的商品量之间有明显差别,我国的天然气统计工作和消费量规划中应关注此问题;⑦在天然气规划中应注意到管线的建成与达到其设计能力之间的时间差。

Natural gas as commodity was achieved from underground energy resources through an extremely complex process,and a number of technical terms are easy to confuse,which has a bad impact on the statistical work and forecast of natural gas resources and the related deep investigations.In view of this,this paper discusses several issues in the statistical work and forecast of natural gas resources in China.(1) Underground natural gas is either trapped in reservoirs or exists in the form of solution gas(associated petroleum gas).The output of the former is rapidly increasing while that of the latter is declining,so the two different forms of gas output should not be confused in statistical forecasting.(2) Tight gas belongs to unconventional gas in USA,but in China,it belongs to conventional gas,so only relying on such statistical data,we can not see the real difference between these two countries when discussing the proportion of unconventional gas in natural gas production or the proportion of shale gas in unconventional gas.(3) Great difference in production control factors,composition,and utilization ratio,exists between CBM gas extracted by surface drilling and that(or coal mine gas) discharged from underground,both future outputs of which need to be re-predicted respectively.(4) Before preliminary reconnaissance prospecting,without any accessible basic indexes of reflecting the gas-bearing property and commercial potential in series of strata with certain underground depths in study areas,we all know that the reliability of the data resulting from its resources potential evaluation is very poor.(5) Although shale gas is in wide distribution,its exploration and development still need to experience the reconnaissance prospecting for the selected exploration area,then from which to find the right point to tap.Shale gas should be developed gradually with its special characteristics made clearer and adapted to China's external environment,so its development goal should not be too high at the initial stage.(6) There is apparent difference between well head production,input amount of pipeline inlet gateway stations or LNG receiver stations,and the commodity amount available to customers,which should be highly concerned especially in statistical work and planning on the gas consumption volume.(7) The time gap between the construction accomplishment and achieving its designed capacity for a pipeline network should be highlighted in natural gas planning.