鄂尔多斯盆地马岭地区长8油藏分布规律

Law of distribution of Chang8 reservoirs in Maling area of Ordos Basin

鄂尔多斯盆地马岭地区延长组长8油层组分为长81和长82共2套油层，长8，与长8：油藏分布特征不同，为了弄清长81和长82油藏分布规律及差异原因，通过室外岩心观察和室内大量的钻探、分析化验资料，对长81和长82小层的沉积、储层、油藏特征差异进行了对比研究，认为长81油藏富集于水下分流河道微相和长石溶蚀作用形成的相对高渗储层．长82油藏分布于滩坝微相和绿泥石膜胶结作用形成的相对高渗储层。总结出马岭地区长8油藏的形成规律，长7烃源岩在主要生烃期生成的油气在异常过剩压力的驱动下，通过近源叠置砂体和裂缝向下运移，在长81多期水下分流河道砂体中普遍成藏；在油源充足、源储压差较高的地区，油气可以沿裂缝继续向下运移，在长82相对高渗的滩坝砂聚集成藏。有效源储配置使马岭地区长81油层近源砂体大面积成藏．长82油层高压点式充注相对高渗储层成藏。

The Chang 8 oil reservoir group of Yangchang Formation in Maling area, Ordos Basin is divided into two sets of Chang 81 and Chang 8, oil reservoirs. The characteristics of oil reservoir distribution in the Chang 81 are different from that of the Cllang 82. In order to understand fully the distribution laws of the Chang 81 and Chang 82 reservoirs and the reasons of their differences, the differences between the sediments, reservoirs and oil reservoir characteristics of the small layers of the Chang 81 and Chang 82 were studied by comparison and through outdoor observation of cores and indoor analysis of extensive drilling and test data. It is believed that the Chang 81 oil was enriched in the relatively high permeability reservoirs formed by the underwater distributary channel mierofacies and fehtspar dissolution, while the Chang 82 oil was distributed in the relatively high penueability reservoirs formed by beach bar microfacies and chlorite fihn cementation. The authors have summarized the formation law of Chang8 oil reservoirs of Maling area in the article. The hydrocarhon （oil/gas） generated by the Chang7 source rock in the major hydrocarbon generation period was driven by the abnormally surplus pressure, anti migrated down through the near-source superimposed sand-body and fissures, and formed extensively a SRCA in muhiphase underwater distributm7 channel sand-body of Chang 81 In the area （s） where the oil snurce was adequate and with high pressure differences between the source and reservoir （s）, the oil/gas could migrated continuously downward along the fractures, and accunmlated in the relatively high permeability beach bar sand-body of Chang 8, to form a SRCA. Overall, an effective source-reservoir configuration made the near-source sand-body of Chang 81 reservoirs form a large-area SRCA in Maling area, while the relatively high permeability reservoirs were filled by points at high pressure to form SRCA in the Chang 8, reservoirs.