摘要
长庆油田对渗透率为0.3～1 mD的超低渗透油藏已实现了规模有效开发。考虑到鄂尔多斯盆地石油勘探开发实际,将储集层地面空气渗透率小于0.3 mD,赋存于油页岩及其互层共生的致密砂岩储层中,石油未经过大规模长距离运移的油藏称为致密油,包括致密砂岩油和页岩油2大类。延长组致密油主要发育于半深湖—深湖相区,以延长组7段(简称长7)油层组油页岩、致密砂岩和湖盆中部的延长组6段(简称长6)油层组致密砂岩最为典型。致密油具有分布范围广,烃源岩条件优越,砂岩储层致密,孔喉结构复杂,物性差,含油饱和度高,原油性质好,油藏压力系数低的特点。纳米级孔喉系统广泛发育是致密油储集体连续油气聚集的根本特征,延长组致密砂岩储层中大多数连通的孔喉直径大于临界孔喉直径,满足油气在致密储层中运移的条件。根据致密油层与生油岩层的接触关系,确定了3种致密油储集层类型:①致密块状砂岩储层;②砂岩-泥岩互层型储层;③油页岩型致密储层。鄂尔多斯盆地长6和长7油层组致密油分布广泛,初步预测致密油总资源量约30×108t,其中长7油层组页岩油资源量超过10×108t,长7油层组致密砂岩油资源量约9×108t,长6油层组致密砂岩油资源量约11×108t。致密油资源是长庆油田实现年产油气当量5 000×104t并长期稳产较为现实的石油接替资源。
The Changqing Oilfield Company has extensively and efficiently developed reservoirs with ultra-low permeability between 0.3 mD and 1 mD. Based on the practice of petroleum exploration and development in Ordos Basin, the tight oil herein refers to the oil that accumulates in oil shale or interbedded tight sandstone reservoirs adjacent to source rocks and with surface-air permeability less than 0.3 mD. Generally, this accumulated oil has not yet experienced large-scale and long-distance migration, and thus its accu- mulation includes tight sandstone and tight shale oil reservoirs. The tight oil of Yanchang Formation mainly develops in a semi-deep to deep lake zone, typically in the oil shale and tight sandstone of Chang-7 interval and the tight sandstone of Chang-6 interval of the central lake. Tight oil in Ordos Basin is characterized by a wide distribution, superior conditions of source rocks, tight sandstone res- ervoirs, complex pore-throat structures, poor physical properties, high oil saturation, better oil properties and low pressure coeffi- cient. Wide development of nano-sized pore-throat systems is one of the fundamental characteristics for the oil and gas continuous ac- cumulation of tight oil reservoirs. Most of the connected pore-throat diameters of tight sandstone reservoirs in Yanchang Formation are greater than the critical pore-throat diameter, gratifying the need of oil and gas to migrate in tight reservoirs. Reservoirs of the tight oil in Yanchang Formation can be divided into 3 different types depending on the contact relationship between tight reservoirs and source rocks, i. e. compact massive sandstone reservoirs, sand-shale interbedded reservoirs and tight reservoirs in oil shale. Tight oil is widely distributed in Chang-6 and Chang-7 intervals of Yanchang Formation in Ordos Basin, and it is preliminarily fore- casted that the total resources of tight oil in Ordos Basin are about 30 ×10^8t, of which the shale oil resource in Chang-7 interval ex- ceeds 10× 10^8 t, while the tight sandstone oil resource in Chang-7 and Chang-6 intervals amounts to about 9× 10^8 t and 11 × 10^8t, re spectively. Therefore, tight oil resources are the realistic oil replacement resources that can ensure Changqing Oilfield to achieve an annual output of 5 000 × 10^8tons of oil equivalent and a long term stability of oil production.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2013年第1期1-11,共11页
Acta Petrolei Sinica
基金
国家重大科技专项(2011ZX05044
2011ZX05001)资助
关键词
致密砂岩油
致密页岩油
致密油
致密油储层
资源潜力
延长组
鄂尔多斯盆地
tight sandstone oil
tight shale oil
tight oil
tight oil reservoir
resource prospect
Yanchang Formation
Ordos Basin
