安岳气田灯影组内幕优质储层的重新认识及其意义

四川盆地安岳气田上震旦统灯影组气藏顶部已经完成整体开发部署,其内幕是潜在的接替层系。但是,灯影组内幕优质储层在地震剖面上识别困难,限制了对灯影组内幕储层的深化认识和勘探开发。为此,利用安岳气田录井、测井等资料开展优质储层测井、地震响应特征分析,利用地震正演建立优质储层地震响应模式,针对有效信号弱的问题开展目标处理,并预测了灯影组内幕优质储层的平面分布和勘探有利区。研究结果表明:①灯影组内幕存在密集孔洞型和独立洞穴型两种类型的优质储层,其中独立洞穴型储层纵向上主要集中在灯三段泥岩底板之上100 m的范围内,沿水平方向顺层发育岩溶带,横向上呈现出散点、珠状特征,规模小;②优质储层在碳酸盐岩内幕的地震响应表现为单波峰的隐蔽型"珠状"反射特征,波峰能量相对较弱,易被地震噪声所掩盖;③采用深层弱信号恢复处理技术可以较好地解决优质洞穴型储层地震响应弱的问题,提高地震资料的保幅性和信噪比,在地震剖面上得到近似串珠的珠状反射,实现优质洞穴型储层的有效识别。结论认为:①深层弱信号恢复处理结果符合已钻井和地震正演结论,该技术具有可操作性;②灯四段底部发育优质洞穴型储层,局部呈规模分布,是安岳气田下一步天然气勘探开发有利的接替层系之一。

Reunderstanding and significance of high-quality reservoirs of the inner Dengying Formation in the Anyue Gas Field

The overall development of the top of the gas reservoir of the Dengying Formation, Upper Sinian in the Anyue Gas Field of the Sichuan Basin, has been deployed, and the inner Dengying Formation is the next potential succession layer. However, the high-quality reservoirs of inner Dengying Formation are undeveloped and cannot be identified on the seismic sections, which restricts its deepened understanding, exploration and development. In this paper, the logging and seismic response characteristics of high-quality reservoirs were analyzed using the mud logging and well logging data of the Anyue Gas Field, and a seismic response model for high-quality reservoir was established by means of seismic forward modeling. Then, the target processing was carried out for the problem of weak effective signals. Finally, the plane distribution of high-quality reservoirs of inner Dengying Formation and the favorable exploration areas were predicted. And the following research results were obtained. First, there are two types of high-quality reservoirs inside the Dengying Formation, i.e., concentrated vug type and independent cave type. Vertically, the independent cave reservoirs are mainly distributed within 100 m above the mudstone floor of the third Member of Dengying Formation. Horizontally, karst zones are developed along the bed. Laterally, they are scattered and beaded. And the scale is small. Second, seismic response of high-quality reservoirs inside the carbonate rocks is characterized by single-peak concealed "beaded" reflection, whose peak energy is relatively weak and can be easily covered by the noise of seismic data. Third, deep-seated weak signal recovery and processing technology can be used to deal with the weak seismic response of high-quality cave reservoirs, improve the amplitude preservation and S/N ratio of seismic data, and obtain the beaded reflections on seismic sections so as to realize effective identification of high-quality cave reservoirs. In conclusion, the deep-seated weak signal recovery and processing technology is proved to be operable because the achieved results conform to the drilling data and the seismic forward modeling conclusions. In addition, high-quality cave reservoirs are developed at the bottom of the fourth Member of Dengying Formation, and they are locally distributed in a large scale. Therefore, it's one of the favorable succession layers for the following natural gas exploration and development of the Anyue Gas Field.