加里曼丹岛库泰盆地海相成藏组合特征及油气富集区分带性分析

Characteristics of Lower Miocene marine petroleum play and prospective petroleum accumulation region in the Kutei Basin, the Kalimantan Island

通过系统收集和分析库泰盆地钻井岩屑样品及野外露头样品,首次对下中新统海相油气系统进行了评价。结果发现该区域以生物礁碳酸盐岩为标志层,发育多套海相沉积旋回,海相沉积油气系统具有自生自储自封堵特征:暗色海相泥岩为主力烃源岩,海相砂岩为有利储层,同时,海相泥岩作为有效盖层。下中新统海相烃源岩样品有机质类型为Ⅱ/Ⅲ型,以Ⅱ型为主,总有机碳质量分数(TOC)平均值 1.92%,有机质处于低熟-成熟阶段,为有效烃源岩,烃源岩厚度较大,指示良好的生烃潜力;储层多期发育,具有低阻特征。自西向东,库泰盆地油气成藏系统时代变新、层系变浅:①盆地东部望加锡海峡深水-半深水区域以上中新统-上新统深水沉积成藏系统为主;②中部马哈坎三角洲-浅海区域以中中新统三角洲相成藏组合为主;③马哈坎褶皱带以下中新统海相成藏组合为主;④盆地西部以渐新统-始新统裂谷期成藏组合为主。新层段海相油气成藏系统的发现,揭示了库泰盆地有利成藏组合的分带规律,指明了库泰盆地中西部区域的未来油气勘探方向。

In this study, the Lower Miocene marine petroleum system was evaluated based on systemic sample col- lection and analysis, including cutting samples from wells and rock samples from outcrops. The analysis results re- vealed multiple similar marine sediment sequences developed in this area, which were indicated by the presence of carbonate rocks. The marine petroleum system has the following characteristics: a thick dark shale acted both as major source rock and seal rock, while the marine sand acted as an efficient reservoir. The source rock was dominated by kerogen type Ⅱ/Ⅲ and major type Ⅱ, with the average total organic carbon (TOC) value of 1.92%. Meanwhile, the maturity of source rock, which was in its early mature period to mature period, implied efficient marine source rock for this petroleum system. Furthermore, the great thickness of source rock implied favorable hydrocarbon generation potential. The marine sand reservoir, which is developed in multiple stages, exhibited low-resistivity feature. From east to west in the Kutei Basin, the petroleum play exhibited an oldening and deepening trend:① Upper Miocene to Pliocene deep water petroleum play in the east Kutei Basin of the Makassar Strait,② Middle Miocene deltaic petro- leum play in Mahakam delta and shallow marine area, the Central Kutei Basin,③ Lower Miocene marine petroleum play in Mahakam fold, and ④ Eocene to Oligocene rift petroleum play in uplifts, the west Kutei Basin. The disco- very of a new efficient marine petroleum system not only reveals the different plays in different structural zones of the Kutei Basin but also provides significance for future explorations in the western part of the Kutei Basin.