岩溶风化壳型含水气藏气水分布特征及开发技术对策——以鄂尔多斯盆地高桥区下古气藏为例

Gas-water distribution characteristic of the karst weathering crust type water-bearing gas reservoirs and its development countermeasures:Case study of Lower Paleozoic gas reservoir in Gaoqiao,Ordos Basin

岩溶风化壳型气藏是一种重要的碳酸盐岩气藏类型,在我国广泛分布于鄂尔多斯盆地、塔里木盆地和四川盆地。受地层水影响,岩溶风化壳型含水气藏的开发面临极大的难题。该类气藏主要表现为储层大面积展布、多层含气,储层薄、丰度低、非均质性强,气井动态特征差异较大,生产井受地层水影响严重等特征。气水分布主要受区域构造背景、气源的充足程度、小幅度构造、储层的非均质性、沟槽的分布及构造反转的地质过程等因素影响。高桥地区完钻水平井动静态特征分析表明,地层水影响是造成水平井生产效果较差的主要因素。针对动态和静态方法在研究地层水分布特征的过程中存在的各自的缺点和不足,结合各自的优点,首次采用动静态结合的方法进行储渗体类型划分,将储层划分为高渗无水、高渗凝析水、高渗封存水、低渗封存水、低渗凝析水和低渗无水6种储渗体,同时在平面上明确各类储渗体分布特征。在气水分布控制因素及储渗体分布特征基础上,制定了岩溶风化壳型含水气藏开发技术对策,为该类气藏科学高效开发提供技术支撑。

Karst weathering crust gas reservoir is a main type of carbonate gas reservoir, which is widely distributed in the Ordos,Tarimand Sichuan Basins.Due to the influence of formation water, the development of karst weathering crust typewater-bearing gas reservoir is facing a great challenge.This kind of gas reservoir is mainly characterized by large area distribution, multilayer gas bearing, thin reservoir, low abundance, strong heterogeneity,and big difference in gas well dynamic characteristics.The controlling factors of gas water distribution mainly include regional tectonic background, sufficient degree of gas source, small amplitude structure, the heterogeneity of reservoir, the distribution of the groove and the geological process of tectonic inversion and so on.The analysis of static and dynamic characteristics of drilled horizontal well in Gaoqiao shows that the main reason to cause the poor production effect is formation water. Aimed at their shortcomings and combined with their respective advantages of dynamic and static methods in the process to analyze the formation water distribution, the dynamic and static method was used to classify storage-permeability body for the first time.The reservoir is divided into high permeability without water, high permeability with condensate water, high permeability with sealed water, low permeability with sealed water, low permeability with condensate water and low permeability without water. At the same time, the distribution of all kinds of storage-permeability bodies is clearly exhibited on the plane.Based on the controlling factors of gas water distribution and storage-permeability body distribution characteristics, the development countermeasures of this kind of gas reservoir were proposed.This effectively guides the scientific and efficient development.