准东北部平地泉组致密油源岩生烃特征

Hydrocarbon supplying characteristics of tight oil source rocks in Pingdiquan Formation,northeastern Junggar Basin

准东北部平地泉组油藏为自生自储型油藏,原油主要来自平地泉组,储层致密、砂泥互层频繁,源岩的供烃能力是该区致密油勘探的主要制约因素。通过对该区平地泉组源岩有机质丰度、有机质类型和成熟度的研究,表明该区平一、二段烃源岩有机质丰度高,有机质类型较好,目前处于低熟—成熟阶段,具有较强生烃能力,但不同区块主力生烃层段纵向分布特征存在差异。该区平一、二段源岩生烃中心具有继承性,主要存在3个生烃中心,分别为火烧山背斜—火东—火南区块,石树沟凹陷和五彩湾凹陷彩2—滴南1井区。源岩演化主要受构造演化的影响,火东向斜和石树沟凹陷源岩成熟度最高,目前已达生烃高峰期;火南斜坡区和五彩湾凹陷次之,目前处于成熟阶段早期;火烧山背斜、火北、沙东地区和帐篷沟地区成熟度较低。目前勘探成果主要集中在火烧山背斜—火东—火南区块生烃中心,石树沟凹陷和五彩湾凹陷彩2—滴南1井区具较大勘探潜力。

In the northeastern Junggar Basin, oils were selfgenerated and selfpreserved in the Pingdiquan Formation. Because of tight reservoir and frequent sand-shale interbedding, the hydrocarbon supplying ability of source rocks is the key factor of tight oil exploration in the study area. The studies of organic matter abundance, type and maturity of source rocks from the Pingdiquan Formation showed that the source rocks from the first and second members of the Pingdiquan Formation are featured by high organic matter abundance and favorable organic matter type, and are during the lowmature and mature stages, hence have high ability of hydrocarbon supplying, but the vertical distribution of main hydrocarbon supplying sections varies among different regions. The hydrocarbon supplying centers in the first and second members of the Pingdiquan Formation have inheritance. There are three hydrocarbon supplying centers including the Huoshaoshan anticline-Huodong-Huonan area, the Shishugou Sag, and the Cai2-Dinan1 well area in the Wucaiwan Sag. Source rock evolution was affected by structure. The source rocks in the Huodong Syncline and Shishugou Sag are the most mature, and have reached hydrocarbon generation peak, while those in the Huonan Slope and WucaiwanSag take the second place, and are in the early mature stage. The source rocks in the Huoshaoshan Anticline, Huobei, Shadong and Zhangpenggou areas have the lowest maturity. The present exploration achievements have been made mainly in the Huoshaoshan Anticline, Huodong and Huonan areas, while the Shishugou Sag and the Cai2-Dinan1 well area in the Wucaiwan Sag also have good potential.