关键词: 岩性油气藏, 地层油气藏, 连续型油气藏, 大型浅水三角洲, 砂质碎屑流, 成岩相

Abstract:

Accompanied by the great development of hydrocarbon exploration,lithologic accumulation exploration areas have changed from the reservoirs with clear traps into the continuous petroleum accumulations with geographically extensive reservoirs,while stratigraphic accumulation exploration areas have turned from the eastern pelvic floor bedrock buried hill hydrocarbon accumulations into the Midwest large unconformity-controlled large-scale stratigraphic reservoirs.Depending on whether the traps have clear boundaries and distribution of oil and gas accumulations,reservoirs are divided into trap-type and non-trap "continuous-type".The major characteristics of continuous petroleum accumulations include lack of obvious trap boundaries,low or ultra-low porosity and permeability,in-source or near-source distribution,limited role of buoyancy in hydrocarbon accumulation,mainly non-Darcy flow,no migration or mainly primary migration,abnormal pressure,complex distribution of oil,gas and water,etc.Continental sedimentary sand bodies in the shallow-water delta depositional system and its sandy debris flow are geological foundations for continuous petroleum accumulations.Quantitative assessment on diagentic facies is an important way to evaluate the low or ultra-low porosity and permeability continuous reservoirs.Deep-water "sandy debris flow " gravity-cause depositional model in basin centers represented by Chang 6 Formation in Ordos Basin expands new fields for oil exploration in the basin centers of China.The concepts,classification,and evaluation methods of diagenetic facies represented by Xujiahe Formation in Sichuan Basin are systematically proposed using the rate of compaction,cementation and dissolution,providing the reference and industrialization evaluation methods for the favorable reservoir evaluation.The continuous petroleum accumulations have great exploration potential in China.

Key words: lithologic hydrocarbon accumulations, stratigraphic petroleum accumulations, continuous petroleum accumulations, large shallow-water delta, sandy debris flow, diagenetic facies