鄂尔多斯盆地郝滩地区延安组延8—延10油藏富集规律

Enrichment patterns of Yan8-10 oil reservoirs in Yan′an Formation of Haotan area,Ordos Basin

鄂尔多斯盆地郝滩地区延安组下段油气显示优越,是长庆油田常规油气藏稳产增产的主力层位。但研究区内延安组储层特征研究程度低,油藏富集规律不明,严重制约了油藏的勘探开发和油田增产稳产工作的推进。在前人研究的基础上,结合储层特征研究,对郝滩地区延安组的成藏控制因素进行分析,并结合现有油藏的精细解剖,探讨研究区延安组下段油藏的富集规律并解剖其成藏模式。研究结果表明,郝滩地区延8—延10储集砂岩物性高,整体为中孔、中—低渗储层,主要的储油空间为粒间孔和长石溶孔;沉积—成岩—构造耦合作用控制郝滩地区延安组下段石油富集成藏,沉积—成岩耦合共同控制延安组下段优质储层发育与分布,而局部发育小幅度构造隆起形成的圈闭有利于石油富集保存;郝滩地区延安组油藏主要为古地貌油藏和岩性—构造油藏,以斜坡古地貌成藏模式、河间丘构造—岩性成藏模式及坡咀岩性—构造成藏模式为主。

The lower section of Yan′an Formation in Haotan area of Ordos Basin has superior oil and gas display,and it is the main oil layer for stabilizing and increasing production of conventional oil and gas reservoirs in Changqing Oilfield.However,the reservoir characteristics of Yan′an Formation in the study area are poorly characterized,and the reservoir enrichment law is unknown,which seriously restricts the exploration and development of the reservoir and the advancement of the work of increasing and stabilizing the production of the oilfield.On the basis of previous research,this paper analyzed the accumulation control factors of Yan′an Formation in Haotan area by combining with the reservoir characterization study,and explored the enrichment law of the lower section of Yan′an Formation in the study area and dissected its accumulation mode by combining with the fine dissection of the existing reservoirs.The results show that the Yan′an 8-10 reservoir sandstones in Haotan area have high physical properties,and the whole is a medium pore with medium-low-permeability reservoir,with the main oil storage spaces being intergranular pores and feldspathic pores.Sedimentation-diagenesis-tectonic coupling effect controls the oil enrichment and accumulation in the lower part of Yan′an Formation in Haotan area.Sedimentation-diagenesis-tectonic coupling controls the development and distribution of high-quality reservoirs in the lower part of Yan′an Formation,and the local development of small-amplitude tectonic uplift formation of the trap is favorable for oil enrichment and preservation.The oil reservoirs of the Yan′an Formation in Hao Tan area are mainly paleomorphic oil reservoirs and lithologic-tectonic oil reservoirs,which are mainly composed of three accumulation modes,including slope ancient landform formation mode,inter-river mound structure-lithology accumulationmode and slope nozzle lithology-structural accumulation model.