| 塔里木盆地西南部皮山北新1井角砾岩的地层归属、成因及油气勘探意义 |
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| 引用本文： | 岳勇,田景春,赵应权.塔里木盆地西南部皮山北新1井角砾岩的地层归属、成因及油气勘探意义[J].地球科学,2019,44(11):3894-3909. |
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| 作者姓名： | 岳勇 田景春 赵应权 |
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| 作者单位： | 1.成都理工大学沉积地质研究院, 四川成都 610059 |
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| 基金项目： | 中国地质调查局地质调查项目DD20190558中石化科技项目P16112 |
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| 摘 要： | 皮山北新1井（PBX1）位于塔里木盆地西南部的麦盖提斜坡，在该井6 884~7 150 m的角砾岩中发现油迹显示并测试获油流，但目前对于角砾岩其赋存地质年代、形成原因等背景问题仍存在较大争议，制约了该区勘探部署、潜力分析.岩心观察、统计，结合X粉晶衍射分析，表明角砾岩磨圆和分选均较差，成分主要为白色亮晶砂屑（鲕粒）灰岩、浅灰色粉晶云岩、灰色粉晶云岩、深灰色粉晶云岩及少量石英和硬石膏，基质主要为细小的碳酸盐岩角砾胶结而成.角砾岩地层下部发现较多时代以晚白垩世为主的孢粉微体古生物化石；放射年代学结果表明，角砾岩地层碎屑锆石年龄分布范围为2 529~127 Ma，其接受陆相沉积物源时间及地层形成年代不早于127 Ma.综合岩石地层、古生物地层、同位素测年，认为皮山北新1井角砾岩地层为晚白垩世依格孜牙组或与之相当的层位.角砾岩平面分布局限，上超于二叠系地层之上，赋存受控于下覆热底劈作用形成环形凹陷区域.受前期破火山口和后期侵入杂岩构造影响，晚白垩世台地相碳酸盐岩破碎，近源堆积在皮山北负向构造区域内.皮山北新1井油藏油气来源于寒武系，岩浆侵入刺穿古生界巨厚碳酸盐岩、碎屑岩地层，形成"直立的不整合面"，沟通寒武系烃源岩，火山活动产生的高角度断裂使得油气运移至中新生界储盖组合中，形成底水构造-地层油气藏.塔西南白垩纪有望成为油气勘探新的突破领域，破火山口边缘带断块圈闭及与中央穹窿火成岩相关的岩墙遮挡等特殊圈闭，是下步油气勘探的有利目标.
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| 关 键 词： | 塔西南 角砾岩 白垩系 破火山口 侵入杂岩构造 断块及火山岩遮挡型圈闭 油气地质 |
| 收稿时间： | 2017-05-04 |
Stratigraphy,Origin and Significance of Oil and Gas Exploration of Cretaceous Breccia in Well PBX1, Southwestern Tarim Basin |
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| Abstract: | Well PBX1 is located on Markit slope in the southwestern Tarim basin, and gets oil flow from the breccias upon the testing after oil show at the depth of 6 884-7 150 m.However, the stratigraphy age and formation reasons of the breccia still remains in dispute, which limits the exploration deployment and potential analysis in this area. Core observation and X-ray powder diffraction test show that the degree of breccia roundness and size classification are relatively poor. The compositions of breccia are white sparite psammitic composition (oolitic) limestone, light gray powder dolomite, grey powder dolomite, dark grey powder and a small amount of quartz and anhydrite, and its matrix mostly is cementation of carbonate gravels with fine grain. Many pollen microfossils are found in the lower part of objective formation, the age of which mainly is Cretaceous. Detrital zircon ages range from 2 529 to 127 Ma in the study area, and the age of sedimentation influenced by the terrigenous provenance is after 127 Ma. The comprehensive analyses of lithostratigraphy, biostratigraphy and isotope dating indicate that the age of breccia in Well PBX1 belongs to Yigeziya Formation of Late Cretaceous. The distribution scale of breccia is limited, which overlaps on the strata of Permian and is controlled by hot bottom split underground forming circular depression. Effected by the former caldera and later intrusive complex structure, Late Cretaceous platform facies carbonate fragmentate and deposit in the negative structures of north Pishan Mountain. The oil and gas resources of Well PSX1 were derived from Cambrian. The magmatic intrusion pierces the huge thickness of Paleozoic carbonate and clastic strata, forming a vertical unconformity surface which links up the source rock. The hydrocarbon migrates to the Mesozoic and Cenozoic reservoir-roof combination and gathering with the help of high angle faults, which were created by the volcanism, and form bottom-water structure formation oil reservoir. The Cenozoic of southwestern Tarim basin will be the next breakthrough of hydrocarbon exploration. Fault block traps around calderas edge and special traps which are sheltered by central arched-roof igneous-rock are the favorable targets of further hydrocarbon exploration. |
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