鸡西含煤沉积盆地特征及早期油气勘探

鸡西盆地位于黑龙江省东部，1985年见天然气显示，有效勘探面积只占盆地面积的50%，而且生油坳陷（沉积坳陷）局部遭到破坏，地质条件复杂，勘探风险大。盆地内主要充填了白垩系及第三系，是一个中、新生代盆地，其中下白垩统分为鸡西群和桦山群，鸡西群是主要含煤地层，也是油气勘探的目的层。下白垩统东荣组含有海湾湖相暗色泥岩，而城子河组与穆棱组沼泽相煤和高碳泥岩发育。老第三系永庆组深湖相暗色泥岩丰富，生油岩类型及纵向分布层位差异受沉积充填序列控制。孔隙型储层物性较低，裂隙型储层具有实际意义。生储盖组合匹配，发现的天然气源于下伏的鸡西群，气层之上的盖层是厚层泥岩与4层凝灰岩。研究表明，鸡西盆地含有较丰富的天然气资源，大部分为煤层气，应以天然气勘探为目标。建议在梨树镇坳陷下白垩统找气，在平阳镇坳陷老第三系找油。

CHARACTERISTICS AND EARLY STAGE PETROLEUM EXPLORATION IN JIXI COAL-BEARING BASIN

The Jixi Basin is located in the east of Heilongjiang Province, in which natural gas was found in 1985. It is a Mesozoic-Cenozoic basin, with Cretaceous System and Tertiary System. The Lower Cretaceous is divided into Jixi Group and Huashan Group. Jixi Group contains coal as well as oil and gas. Dongrong Formation(K1 d) has lots of dark mudstones deposited in indented lagoon. Coal and highly carbonaceous mudstones of marsh are rich in Chengzihe Formation (K1 ch) and Muleng Formation (K1 m). There is a good deal of deep-lake mudstones in Yongqing Formation (E2 y) . The type and vertical distribution of source rocks were controlled by fill sequence. Porous reservoir has lower porosity and permeability, and fractured reservoir is dominant. Source-reservoir-seal assemblage is good. The gas of well blowout is from lower coal-bearing strata ( K1 ch and K1 m ) , and gas layer is at the middle of Muleng Formation reservoir. The caprock of thick mudstones and 4 tuff beds were located above the gas. Jixi Basin is a gas-bearing basin. The prospecting for gas in Lishuzhen depression and oil in Pingyangzhen depression is suggested.