摘要
鄂尔多斯盆地致密油储量丰富,主要富集在延长组三叠系长6和长8油层组,是目前增储上产的重要目标。为了推动该类油藏的规模效益开发,以深化储层特征与渗流规律认识为目的,在前期研究基础上,引入核磁共振、高压压汞、纳米CT扫描和高精度流体计量等新技术,系统开展了致密油储层微观孔隙结构、原油赋存状态以及水驱与渗吸动用规律研究。研究成果表明,致密油储层发育多尺度孔隙,孔隙结构以小孔-细喉型为主且连通性较好。物理模拟研究表明,原油在致密油储层的各类孔隙中均有分布,但大、中孔隙中原油的含量远高于小孔隙中的原油含量,且多以游离态存在,流动性好,是油田开发的主要对象。水驱油实验表明,致密油储层虽然存在启动压力梯度,但当驱替压力大于启动压力之后能够建立有效驱替系统,且随着驱替压力的增大水驱油效率会有所提高。核磁共振技术与水驱油实验或渗吸实验相结合,清楚地表明了不论采用水驱方式还是渗吸方式开发,致密油储层优先动用的都是较大孔隙中赋存的原油,小孔隙中赋存的原油动用难度较大。这些研究成果为探索更加有效的开发技术提供了依据。
Tight oil is rich in Ordos Basin,mainly well-developed in Chang6&Chang8 reservoir groups of Yanchang Formation.Currently,it is an important goal to increase reserves and production.This study deepens the understanding of reservoir characteristics and flow laws to push forward the large-scale effective development of such reservoirs.Based on the previous research,this study introduced new techniques of nanometer-scale CT scanning,NMS,and high precision fluid metering to systematically study microcosmic pore-throat characteristics,occurrence phases of crude oil,water displacement and imbibition features in tight oil reservoirs.The research results show that multi-scale pores exist in tight oil reservoirs,dominated by the assembly of fine-pore and thin throats with good connectivity.Physical simulation studies show that the content of crude oil in large and medium pores is much greater than that in small pores,and the crude oil in a free state with good flowability is main object of oilfield development.The water displacement experiments indicate an effective displacement system can be established when displacement pressure is greater than the threshold pressure gradient in tight oil reservoirs.Water displacement efficiency could be improved with increasing displacement pressure.Laboratory results of NMS combined with water displacement and imbibition experiments show clearly that crude oil mainly contained in relatively large pores is produced previously,while that in small pores is hard to produce,no matter how it is developed by means of water[JP2]displacement or imbibition.The research results can provide evidence for seeking more effective development technology.
作者
李书恒
王永宏
邓秀芹
孙栋
杨子清
LI Shuheng;WANG Yonghong;DENG Xiuqin;SUN Dong;YANG Ziqing(Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China;National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields,Xi’an 710018,China)
出处
《非常规油气》
2024年第2期80-91,共12页
Unconventional Oil & Gas
基金
中国石油重大科技专项“致密油勘探开发技术研究”(2021DJ2203)。
关键词
致密油储层
孔隙结构
水驱油实验
渗吸实验
鄂尔多斯盆地
tight oil reservoirs
pore structure
water displacement experiment
imbibition experiment
Ordos Basin
