摘要
川西坳陷陆相沉积领域浅、中层(深度大约在500-3000 m)天然气藏属近常规到致密砂岩远源气藏。这些气藏主要分布在侏罗系─白垩系的地层中,并形成了如新场气田、洛带气田、新都气田、马井气田等大、中型气田。川西坳陷的中、浅层气藏具有储层发育良好、输导条件较好、储层展布与构造配置关系好及封盖保存条件良好等特点。储层沉积微相以三角洲前缘毯状砂体、三角洲前缘分流河道砂体、河口坝砂体和湖底扇砂体等为主,储层地球物理特性通常表现为低波阻抗特征,与围岩具有良好的波阻抗差异。川西坳陷地震地质条件较差,地表覆盖有几米至200多米厚的卵石和沙土,高频吸收严重,原始地震记录干扰波(面波、声波及折射波)发育,信噪比较低。因此,川西坳陷中、浅层气藏储层识别成功的关键技术是卵石覆盖区高精度的三维地震采集、保持含气地震响应特征的三维地震资料处理、正演模拟指导下的储层地震属性提取及分析和储层空间展布刻划及多学科协同的综合评价等。川西中、浅层气藏的勘探开发实践表明,地震勘探技术在气藏分布范围确定、空间几何形态描述、储层物性参数反演、沉积相和储层非均质性研究以及高产富集带预测、含气性识别等方面发挥了十分关键的作用。
The non-marine shallow-middle gas reservoirs （with depth ranging from 500 m to 3 000 m） in western Sichuan depression are near-normal to tight sandstone of distal facies. These reservoirs are mainly distributed in the Jurassic and Cretaceous formations where large-to medium-sized gas fields, such as Xinchang, Luodai, Xindu, Majing, and etc, are harbored. The shallow-middle reservoirs in western Sichuan depression feature in well-developed reservoirs, favorable transportation conditions, ideal matching of reservoir distribution and structure configuration, and good sealing. Sedimentary micro-facies reservoirs are mainly composed of delta front sill-like sand, delta front distributary channel sand, estuarine sand bar, and sublacustrine fan sand. The reservoirs typically show low wave impedance and large wave impedance difference with surrounding rocks. The seismogeological conditions are rather unfavorable in western Sichuan depression, where the surface is covered by unconsolidated pebble and sandy soil beds with thickness ranging from several meters to 200 meters, resulting in severe high frequency attenuation and strong interference waves, such as surface wave, acoustic wave and refraction wave, and low S/N ratio. Therefore, a successful gas reservoir recognition in the study area involves the application of high-precision 3-D seismic data acquisition in areas covered by unconsolidated pebble layers, 3-D seismic processing with gas bearing seismic responses preserved, reservoir seismic attributes extraction and analysis based on forward modeling, and reservoir spatial delineation and multi-disciplinary integrated evaluation. The exploration and production of the shallow-middle gas reservoirs in the study area show that seismic exploration plays an important role in delineation of reservoir distribution, description of the spatial geometry of the reservoirs, inverse modeling of the reservoir parameters, study of sedimentary facies and heterogeneity, determining prolific gas-bearing zone, and recognition of gas-bearing properties.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2006年第6期879-893,894,共16页
Oil & Gas Geology
基金
"九五"国家重点科技攻关项目(99-110-02-05)
关键词
致密砂岩
地震响应
地震属性
空间展布刻划
非均质性
储层识别
远源气藏
川西坳陷
tight sand
seismic response
seismic attribute
reservoir spatial delineation
heterogeneity
reservoir recognition
distal gas reservoir
western Sichuan depression
