珠江口盆地惠州凹陷古近系水溶气资源潜力

Resource potential of water-soluble gas in the Palaeogene Huizhou Sag, Pearl River Mouth Basin

基于水溶气形成基本原理,结合惠州凹陷古近系烃源岩层系地质条件,采用网格化运算方法定量分析了惠州凹陷古近系烃源岩层水溶气资源量及其利用前景。惠州凹陷古近系主力烃源岩文昌组和恩平组生气量充足,其内砂岩储集层整体上处于弱超压—超压状态。根据文昌组与恩平组厚度、砂岩含量、孔隙度、含水饱和度、地层压力、温度、矿化度等参数计算,其水溶气资源量分别为1 791.49×108m3、2 688.5×108m3,相当于常规气资源量的1.19倍、3.46倍;假设地层压力由弱超压—超压降至常压状态,文昌组、恩平组可分别脱溶天然气80.84×108m3、97.04×108m3。可见在富气盆地的高压储集层中,水溶气不仅是潜力巨大的非常规资源,而且通过降压脱溶还可为常压的常规气藏提供可观的气源补充。

Based on the formation mechanism of water-soluble gas,combined with the geological conditions of the Palaeogene Huizhou Sag,the resource potential and utilization of water-soluble gas in the Palaeogene source rock in the Huizhou Sag are analyzed quantitatively using grid calculation method.The Palaeogene Wenchang and Enping Formations of the Huizhou Sag are major source rocks that generate significant quantities of gas and the sandstone reservoirs are weakly overpressured to overpressured on the whole.Calculated according to the thickness,sandstone content,porosity,water saturation,strata pressure,temperature,and mineralization of the Wenchang and Enping Formations,the resource volume of water-soluble gas is about 1 791.49×108m3and 2 688.5×108m3,1.19 and 3.46 times that of the conventional gas,respectively.If the strata pressure is relieved to normal pressure,the degasification volume is 80.84×108 m3 and 97.04×108 m3.The water-soluble gas is an unconventional resource with great potential,and can provide substantial gas source for conventional pools through degasification.