摘要
根据钻井、地震和试气资料,对甘泉—富县地区本溪组的构造、古地貌、沉积相、储层和气水分布规律等进行研究。结果表明,本溪组为潮坪-泻湖-障壁沉积体系,储层主要为东、西两个平行岸线的北西向障壁砂坝砂岩,障壁砂坝分布在古岩溶高带两侧,为浅灰色石英质中粗砂岩和细砾岩。研究区中东部下伏地层为奥陶系马六段,由于缺乏马家沟储层和向下运移的通道,油气主要在本溪组东障壁成藏。研究区西南部本溪组下伏古岩溶凹槽,煤系烃源岩与马五溶蚀灰岩储层侧接,所以奥陶系成为主成藏层位,本溪组西障壁砂岩成藏相对较差。本溪组气藏主要为砂岩透镜体圈闭,少量砂岩上倾尖灭圈闭,气藏沿障壁砂坝中心厚砂体呈串珠状分布。水层主要为单层厚度小于2 m的薄砂层,为潮道或障壁边缘砂岩,个别较厚的水层砂岩平面上位于气藏之间,应该与局部存在的大断距断裂在成藏期的活动和破坏有关。干层为孔隙度小于3.2%或渗透率小于0.07×10^(-3)μm^(2)的致密砂岩,主要为深灰色凝灰质和浅灰色岩屑石英两种砂岩类型,二者测井孔隙度均小于3.2%,显微镜下面孔率<1%。凝灰质砂岩具有颜色深(深灰色,简称黑砂岩)、粒度细(细砂岩或粉-细砂岩)、单层厚度薄(0.5~2 m)的特点,随机夹于浅灰色障壁或潮道砂岩之中,本一段和本二段均可含一层凝灰质砂岩,镜下具火山尘杂基、燧石和岩屑含量高、基底式胶结、颗粒分选和磨圆度差等特点。致密的浅灰色岩屑石英砂岩则具有黏土质和白云质胶结、颗粒线接触-凸凹接触、压实作用强、分布不均匀等特点。根据沉积相和物性对气藏的控制,结合地震属性和含气检测等手段对有利成藏区进行预测,认为研究区本一和本二段各发育两个北西向障壁,障壁砂坝内部为有利高产能区,朝障壁边缘物性变差,产能降低;含水厚砂岩主要受燕山期北北东断裂活动的控制。
Based on drilling,seismic and gas testing data,the structure,paleogeomorphology,sedimentary facies,trap,gas and water distribution are analyzed for Benxi Formation in Ganquan Fuxian area.The results show that reservoirs and stones deposited in tidal-flat-lagoon barrier environment.The sandstones mainly consist of two barrier bars parallel to the NW orientation shorelines,located on both sides of the ancient karst high belt.The underlying stratum in the middle east of the study area is the 6th Member of Ordovician Maiagou Formation.Due to the lack of Majiagou reservoir and downward migration channel,oil and gas are mainly accumulated in the east barrier of Benxi Formation.In the southwest of the study area,the ancient karst groove exited under the Benxi Formation,which make the coal measure hydrocarbon source rock to connect laterally with the karst limestone reservoir of 5th Member of Miajiagou Formation.Therefore,the 5th Member becomes the main gas reservoir while the western barrier of the Benxi Formation is relatively poorly charged with gas.The trap type is dominated by lenticular sandstone bodies,with a small amount of sandstone pinching out traps.The water zones consist mainly of thin sand layers with a single layer thickness of less than 2 m,which is tidal channel or barrier edge sandstone.Some thicker water layer sandstones are located between gas zone laterally,which may be related to the activity and destruction of local large offset faults during the reservoir forming period.The dry zones consist of tight sandstones with porosity less than 3.2%or permeability less than 0.07×10^(-3)μm^(2),mainly composed of dark gray tuffaceous sandstone and light gray lithic quartz.The logging porosity of dry zones is less than 3.2%,or 0~3.2%under the microscope.The tuffaceous sandstone has dark color(dark gray,referred to as black sandstone for short),fine grain size(fine sandstone or silty fine sandstone),thin single layer thickness of about 0.5~2 m,and is randomly sandwiched in the light gray barrier or tidal channel sandstone.The upper and lower Member of Benxi Formatioin may contain one layer of tuffaceous sandstone,which is characterized by high volcanic dust matrix,high content of chert and rock debris,basal cementation,poor particle sorting and roundness.Light grey tight lithic quartz sandstone is characterized by clayey and dolomitic cementation,grain linear contact or stylolite contact,strong compaction and pore uneven distribution.According to the control of sedimentary facies and physical properties on gas accumulation,favorable reservoir distribution are predicted using seismic attributes and gas detection,it is believed that there are two barriers oriented towards the northwest that have developed in each of the first and second sections of the study area.The interior of the sandbar barrier is a highly productive area,while the physical attributes of the barrier’s edge deteriorate,leading to a decrease in productivity.The thick sandstone,which has a high water content,is mainly influenced by the activity of the Yanshanian North Northeast fault.
作者
孟祥振
宋明
蒲仁海
高小平
强腾
吴疆
关蕴文
MENG Xiangzhen;SONG Ming;PU Renhai;GAO Xiaoping;QIANG Teng;WU Jiang;GUAN Yunwen(Oil and Gas Exploration Company,Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Yan’an 716000,China;Department of Geology/State Key Laboratory of Continental Dynamics,Northwest University,Xi’an 710069,China;Sinopec Exploration and Development Research Institute,Beijing 100083,China)
出处
《西北大学学报（自然科学版）》
CAS
CSCD
北大核心
2023年第3期466-479,共14页
Journal of Northwest University（Natural Science Edition）
基金
陕西省重点研发计划项目(2022GY-140)
延长集团油气勘探公司委托项目(KT1321SFW0001)。
关键词
本溪组
古地貌
沉积相
砂体展布
控藏因素
气藏识别
Benxi Formation
paleogeomorphy
sedimentary facies
sandbody distribution
reservoir control factor
gas identification
作者简介
第一作者:孟祥振,男,陕西黄龙人,正高级工程师,从事油气勘探开发地质研究,364178782@qq.com。
