四川盆地荷包场地区二叠系岩溶储层地球物理特征与分布预测

以往对于四川盆地南部中二叠统茅口组岩溶储层的研究多集中于沉积相、储层特征与主控因素、天然气成藏模式及气源对比等方面,井位部署也持续围绕着断裂展开,限于地震资料品质等原因对该套储层的定性分析及定量预测研究程度偏低。为此,基于前人的上述传统研究成果,利用川南荷包场地区的三维地震资料,分析高产气井岩溶储层的地震响应特征,通过模型正演、振幅属性分析及烃类检测等多种方法,开展茅口组岩溶储层的定性分析、定量预测与含烃检测,进而预测岩溶储层的有利发育区。研究结果表明:(1)荷包场地区茅口组岩溶储层纵向上具有分层特征,高产层段主要发育在距离茅口组顶部50 m以内的上部层段;(2)高产层段的茅口组顶部及下部同相轴表现出"弱波峰、弱宽波谷"的地震响应特征;(3)振幅指数属性定量预测和烃类检测结果显示,二者具有较好的一致性,该区存在着3个优质储层发育带,并且与实钻井的吻合度达到了80%。结论认为,荷包场地区除沿着断裂发育储层有利区带外,远离断裂带也发育了3个岩溶储层有利区,3个有利区合计面积为79 km~2;上述认识对于远离断裂在构造斜坡及向斜区进行油气勘探和井位部署具有重要的指导意义。

Geophysical characteristics and distribution prediction of the Permian karst reservoirs in the Hebaochang area,South Sichuan Basin

Previous studies on the karst reservoirs of Maokou Fm, Middle Permian in the Southern Sichuan Basin mainly concentrate on sedimentary facies, reservoir characteristics and controlling factors, gas accumulation patterns and gas–source correlation, and well location deployment is carried out with faults as the focus. Due to the limitation of seismic data quality and other factors, this set of reservoirs are less analyzed qualitatively and predicted quantitatively. In this paper, the seismic response characteristics of high yield gas wells in karst reservoirs were analyzed based on the above mentioned traditional research achievements, combined with the 3D seismic data in the Hebaochang area of the Southern Sichuan Basin. Then, qualitative analysis, quantitative prediction and hydrocarbon detection were carried out on the karst reservoirs of Maokou Fm, Middle Permian by means of forward modeling, amplitude attribute analysis, hydrocarbon detection and other methods. Finally, the favorable areas for the development of karst reservoirs were predicted. And the following research results were obtained. First, the Maokou karst reservoirs in the Hebaochang area are vertically stratified and high yield intervals are mainly developed at the upper sections within 50 m from the top of Maokou Fm. The events of high yield intervals, i.e., top Maokou Fm and the lower part, present the seismic response characteristics of "weak peak & weak and wide valley". The quantitative prediction of amplitude index attribute and the hydrocarbon detection results show that both of them are coincident and there are 3 high-quality reservoir development zones in this area. And their coincidence with the actual wells is up to 80%. It is concluded that besides the favorable reservoir areas developed along the faults in the Hebaochang area, 3 favorable karst reservoir areas are developed far from the fault belt, the total area of which is 79 km2. The research results are of great significance to guiding the oil & gas exploration and well location deployment in the structural slope and syncline areas far from faults.