东濮凹陷致密砂岩气藏特征的研究

致密砂岩气藏的储层,除岩性致密外,与渗透性储层相比较,含水饱和度对其影响更大,孔隙度与渗透率不具线性关系,封闭压力的影响远大于渗透层的影响。致密砂岩气藏的储层分类评价,主要以地下渗透率,再辅以孔隙度等参数为分类指标。其地质特征,主要表现在分布位置——沉积盆地洼陷中,或正向构造过渡的斜坡带上;圈闭类型——属岩性圈闭;并具有含气井段长、含气高度大、地层压力高异常等特点。应以大型三角洲砂体为主要勘探目标,目的层不宜超过4000m,含水饱和度为勘探中的重要参数。

CHARACTERISTICS OF TIGHT SAND GAS RESERVOIR IN ZHONGYUAN OIL FIELD AND ITS EXPLORATION

As compared to conventional sandy gas reservoir, the water saturation of a tight sandy gas reservoir has a higher effect on its identification in addition to its lower permeability. Moreover, no linear relationship is found to be existed between its porosity and permeability and confining pressure has a much more effect than that in the case of a conventional reservoir. The major parameter used in the classification of a tight gas reservoir for its evaluation is subsurface permeability, and porosity comes to the next, The major geological features are: (1) It is located usually in the centre of a sag in the sedimentary basin or on the slop of a transitional zone; (2) It is a lithologic trap usually; (3) It has a high gas column and with pay zones distribution in a fairly long interval; (4) It is usually abnormally high pressure. Large deltaic sand bodies should be taken as a major target for exploration with a depth of burial of <4000m, and attention should be paid to the parameter, water saturation.