研究四川盆地南部上二叠统龙潭组碎屑岩的地球化学特征,探讨其物源特征及古风化、古环境、古氧化-还原条件等地质意义.通过对CLD1井龙潭组岩心的观察描述和薄片鉴定,结合主元素、痕量元素及稀土元素的测试分析等方法对龙潭组沉积期的沉积环境进行讨论.La/Sc-Co/Th图解、∑REE-La/Yb图解及δEu值分析,以及Al2 O3/TiO2-TiO2图解与峨眉山高Ti玄武岩进行对比,结果表明研究区龙潭组物源复杂,主要为峨眉山玄武岩,伴少量钙质泥岩及部分长英质火山岩;Th-Sc-Zr/10和La-Th-Sc三角图分析结果显示龙潭组物源主要来自大陆岛弧;龙潭组样品大陆风化指数平均为85.19,属于中-高强度风化;Sr/Cu质量分数比值介于0.41～26.05(平均值为5.68),MgO/CaO质量分数比值介于0.02～2.35(平均值为0.92),指示龙潭组整体形成于温暖湿润的气候条件,沉积环境为咸水的海陆过渡相环境,晚期为海相沉积环境;古氧化-还原指标[V/(V+Ni)质量分数比值]介于0.59～0.95(平均值为0.81),Th/U质量分数比值介于2.18～5.62(平均值为4.23),Ceanom值介于-0.80～0.10(平均值为-0.01),指示龙潭组沉积水体以贫氧至厌氧的弱氧化至还原性环境为主.龙潭组碎屑岩沉积于温暖湿润条件下的贫氧至厌氧的弱氧化至还原性环境,整体为中-高强度风化,龙潭期沉积水体呈加深趋势.

探讨辽东湾拗陷勘探程度较低的次级构造单元——辽东凸起锦州23构造带的勘探潜力,从烃源特征、储集条件、圈闭类型以及输导体系等分析其成藏条件,恢复其成藏过程.研究结果表明:锦州23构造带具有2套时空匹配关系良好的生储盖组合,储集层为展布范围广、储集性能优越的扇三角洲和辫状河砂体,其与辽中凹陷优质且供烃充足的深湖相烃源岩直接接触,具备有效的油气输导通道;盖层为封闭能力强的深水湖泊相泥岩或较强的河流相泥岩;以规模较大的断块和断背斜为主要类型的圈闭,其形成均早于油气主运移期.锦州23构造带优越的成藏条件以及成藏各要素之间良好的动态耦合关系,具备广阔的油气勘探潜力.辽东凸起上类似于锦州23构造带的一系列圈闭应为今后的勘探新区域.

The middle and lower Cambrian Xixiangchi Formation in the Sichuan Basin is a gas?bearing formation with a good potential. Its exploration degree is still very low at present, and the reservoir characteristics and main controls are not clear. Core, thin section and testing data were integrated to study the rock types, reservoir space, physical properties and controlling factors of the Xixiangchi reservoirs. The Xixiangchi reservoirs are mainly grain dolomites, followed by aplite?dolomites. The reservoir space includes pores, caves and fractures, and the reservoir type is fracture?pore type. The physical properties of the reservoirs are characterized by low porosity and low permeability, and locally high porosity and high permeability, showing a strong heterogeneity. For the distribution, the Xixiangchi reservoirs vertically stacked and have a poor lateral continuity. Thick reservoirs appear from the central Sichuan Basin to well GT 2 in the east, and then thinned in Wubaiti area. In Fengjie and Xishui areas at the basin edge, reservoirs distribute as belts, and are thinner compared to those in the basin center. Reservoir development was controlled by sedimentary facies obviously. In the grain shoal area, reservoirs have a high development degree. Besides, constructive diagenesis and tectonic fracture have positive effects on reservoir development.