Geological control factors of micro oil distribution in tight reservoirs
Geological control factors of micro oil distribution in tight reservoirs
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致密油藏微观石油分布地质控制因素
DOI：
10.1016/j.marpetgeo.2016.08.013
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发表时间：
2016-11-01
影响因子：
4.2
通讯作者：
Zhao, Dongshan
中科院分区：
文献类型：
--
作者：
Cao, Zhe;Liu, Guangdi;Zhao, Dongshan
了解非常规致密储层的油气分布特征对于油气评价和油气开采至关重要。以往对致密油分布特征的研究多集中在盆地尺度上。以芦草沟岩心样品为基础，将索氏提取、总有机碳（TOC）、岩石评价等地球化学方法与压汞毛细管压力（MICP）、孔渗分析等储层物理方法相结合，在微观尺度上定量评价致密储层的油分布。重点是识别此类致密储层微油分布的关键地质控制因素。白云岩和非碎屑泥岩具有较好的生烃能力，而含碎屑的白云岩、粉砂岩和粉质泥岩孔隙度和含油量较高，孔喉半径较粗。含油量主要受孔隙度、孔喉半径和生烃能力的控制。孔隙度与含油量在几乎所有样品（包括各种岩性）中均呈正相关，表明孔隙度是提供储集空间的主要制约因素。孔喉半径也是一个重要的因素，因为油的运移受到毛细压力的抑制，而毛细压力是必须克服的。当孔隙度合适的储层岩石没有生烃能力时，孔喉半径将起决定性作用。致密储层普遍具有纳米级孔喉分布广泛、毛管压力高的特点，因此，孔隙度适宜、孔喉细的储层岩石生烃能力起着重要作用。因为这样的储层岩石不能完全充能。三种高孔隙度岩性（含碎屑白云岩、粉砂岩和粉砂质泥岩）的生烃能力与含油量正相关关系支持了这一论断。(C) 2016 Elsevier Ltd.版权所有。
Understanding the oil distribution characteristics in unconventional tight reservoirs is crucial for hydrocarbon evaluation and oil/gas extraction from such reservoirs. Previous studies on tight oil distribution characteristics are mostly concerned with the basin scale. Based on Lucaogou core samples, geochemical approaches including Soxhlet extraction, total organic carbon (TOC), and Rock-Eval are combined with reservoir physical approaches including mercury injection capillary pressure (MICP) and porosity-permeability analysis, to quantitatively evaluate oil distribution of tight reservoirs on micro scale. The emphasis is to identify the key geological control factors of micro oil distribution in such tight reservoirs. Dolomicrites and non-detrital mudstones have excellent hydrocarbon generation capacity while detritus-containing dolomites, siltstones, and silty mudstones have higher porosity and oil content, and coarser pore throat radius. Oil content is mainly controlled by porosity, pore throat radius, and hydrocarbon generation capacity. Porosity is positively correlated with oil content in almost all samples including various lithologies, indicating that it is a primary constraint for providing storage space. Pore throat radius is also an important factor, as oil migration is inhibited by the capillary pressure which must be overcome. If the reservoir rock with suitable porosity has no hydrocarbon generation capacity, pore throat radius will be decisive. As tight reservoirs are generally characterized by widely distributed nanoscale pore throats and high capillary pressure, hydrocarbon generation capacity plays an important role in reservoir rocks with suitable porosity and fine pore throats. Because such reservoir rocks cannot be charged completely. The positive correlation between hydrocarbon generation capacity and oil content in three types of high porosity lithologies (detritus-containing dolomites, siltstones, and silty mudstones) supports this assertion. (C) 2016 Elsevier Ltd. All rights reserved.