西藏伦坡拉盆地古近系油藏成藏机理及有利区带预测

西藏伦坡拉盆地古近系始新统牛堡组-渐新统丁青湖组的早期勘探发现了良好的油气，展示了较好的勘探潜力，但单井测试多为低产，分析认为成藏机理及主控因素认识不够制约了早期勘探。为弄清伦坡拉盆地古近系油藏成藏机理，明确有利区带，通过地质与物探联合分析，认为伦坡拉盆地具有多套扇三角洲前缘砂岩体目的层系、有利生储盖组合、继承性古隆起（古斜坡）、立体输导体系、构造与成藏匹配好等有利成藏条件。油藏具“近源聚集、多期成藏、中浅层晚期破坏、中深层原地富集”成藏富集规律，评价落实了6个有利勘探区带，采用有机碳法计算资源量达数亿吨，资源丰度较高，具有形成中型油田的资源潜力，其中长山岩性区带成藏条件优越，估算资源量上亿吨，同时该区正好是丁青湖组中下部油页岩发育区，采用体积丰度法计算出其资源量3倍于常规资源量。总体上长山岩性区带为常规与非常规有利油气勘探区的叠合部位，展现出广阔的勘探前景。

Hydrocarbon accumulation mechanism and play fairways of the Paleogene in Lunpola Basin,Tibet

Early exploration in Lunpola Basin shows a good exploration potential within the Paleogene Eocene Niubao and Dingqinghu Formations.However, most of the single well test results are low.The poor understanding of hydrocarbon accumulation mechanisms and their main controlling factors affects the early exploration.In order to clarify the accumulation mechanisms and predict play fairways, a comprehensive study was performed by integrating the geological and geophysical data.It is believed that Lunpola Basin has many good reservoir forming conditions such as multiple sets of fan delta front sandstone systems, favorable source-reservoir-cap rock assemblage, inherited palaeohigh(ancient slope), ste-reoscopic carrier systems and good timing of structure and hydrocarbon accumulation.Hydrocarbon accumulation in Lunpola Basin features in close proximity to the source rocks, multi periods of charging, damage of reservoirs with mid-shallow depth in late stage, in-situ enrichment of hydrocarbons in middle-deep layers.Six play fairways are identified in Lunpola Basin, their resource potential is estimated to be up to several hundred million tons based on calculation with the organic carbon method, and the resource abundance is relatively high, thus it has the potential to form mid-sized oil field.Especially, the Changshan litho-logic play has very favorable reservoir forming conditions and its resource potential is estimated to be up to 100 million tons.In addition, the oil shale is developed in the middle and lower Dingqinghu Formation within the play and its resource volume is three times as large as that of the conventional resources based on calculation with volume abundance method.As a whole, conventional and unconventional plays overlap in the Changshan lithologic zone, thus its exploration potential is huge.