五区上乌尔禾组低孔低渗储层的成因分析

发布时间：2018-05-07 08:01

本文选题：五区 + 上乌尔禾组　；参考：《长江大学》2015年硕士论文

【摘要】：油气储集在储层里,在含油气盆地中,寻找良好的储层成为油气田勘探的重要任务。然而,很多储层并不是那么理想,比如低孔低渗储层。因此,找出造成储层物性差的原因也成为了后期油气开发的核心之一。本文根据沉积岩石学的理论和方法,储层沉积学为指导,将克拉玛依油田乌尔禾组为研究对象,结合岩心资料、测井解释资料、地震资料及实验分析资料等研究了目的层沉积相、成岩作用、储层孔隙结构特征,开展了储层精细描述,探索了低孔低渗储层的控制因素,进而,为后期油气开发提供依据。相对于其他地区的碎屑岩储层而言,五区上乌尔禾组的储层具有特殊性。其他地区的碎屑岩储层多为砂岩储层,储层特征明显便于研究；而五区上乌尔禾组的储层多为砂砾岩储层,该类储层的储层特征复杂,研究起来难度较大。五区上乌尔禾组地层与上覆地层和下伏地层之间存在不整合接触关系；上乌尔禾组可分为三段,即P3W3、P3W2、P3W1。五区上乌尔禾组的沉积物颗粒普遍较粗,多为砂砾岩,此外还有些砂岩和泥岩。通过对研究区的岩性、岩石的颜色、沉积构造特征及测井相的研究,确定了五区上乌尔禾组沉积相类型。五区上乌尔禾组发育冲积扇和扇三角洲沉积相,根据研究区的沉积特征,进而将冲积扇相划分了3个亚相,10个微相；研究区扇三角洲相发2个亚相,进而划分了6个微相。五区砂砾岩多为近物源沉积,砂砾岩搬运的距离比较近,砂砾岩颗粒的成分成熟度和结构成熟度都比较低。砂砾岩颗粒的分选差,磨圆也相对较差。砂砾岩颗粒中凝灰岩岩屑含量高(凝灰岩岩屑含量为46.53%),导致岩石的抗压实能力差。在成岩作用早期,受压实作用的影响,岩石孔隙及喉道快速变小或消失,这是导致储层物性变差的重要原因之一。五区上乌尔禾组碎屑岩中的填隙物以泥质(杂基)为主,胶结物以浊沸石和石膏胶结为主；本区以接触式胶结为主,孔隙式胶结次之。五区的压实作用比较强烈,对储层的影响较大。强压实的作用下,导致研究区砂砾岩体颗粒之间紧密接触,以线接触为主。研究区塑性物质及杂基条带发生弯曲变形,少数刚性颗粒发生破碎。薄片下可见云母矿物发生弯曲变形,部分塑性凝灰岩颗粒受到挤压发生变形,粒间充填物绿泥石杂基与基泥质条带发生弯曲变形。此外,在强压实的作用下泥质或者塑性颗粒被压进孔隙中形成假杂基。五区上乌尔禾组储层中以方解石、沸石类胶结为主,胶结物虽然堵塞碎屑岩中的孔隙,降低储层的物性,但另一方面,长石和方沸石胶结物易被溶蚀,在局部发育形成溶蚀孔隙,对储层物性起着改造作用。五区上乌尔禾组发育的孔、缝主要有：原生粒间孔、剩余粒间孔、溶蚀孔和裂缝等。研究区粒间孔隙含量最高,占总孔隙的32.7%；其次为粒间溶孔和粒内溶孔,粒间溶孔含量约为28.15%,粒内溶孔相对含量为16.22%。五区上乌尔禾组的储层存在一种特殊的储集空间类型即砾缘缝(或称界面缝),界面缝主要由于沉积物埋藏较浅,并且有上部的泥质沉积物下渗充填在砂砾岩之间,在成岩阶段,砂砾岩之间的泥质沉积物失水收缩形成。研究区砾缘缝的含量相对较高,达到9.87%。本文将研究区储层的储集空间进行归类,按储集空间的含量来分,主要分类了五类,即剩余粒间孔型、溶蚀孔隙型、混合孔隙型、致密型和孔隙-裂缝型。研究区储层物性较差,孔隙度普遍15%,渗透率普遍50×10-3μm2。本文按照碎屑岩储层物性分级标准,将研究区的储层定为低孔低渗储层。通过对研究区沉积微相分析和储层特征研究,发现造成研究区储层为低孔低渗储层的因素主要有沉积微相、成岩作用和微裂缝三个因素。泥质含量与孔隙度成反比,泥质含量越低,孔隙度值就越高；同时,岩石颗粒越粗,抗压实能力相对就越强,物性就相对较好。通过对沉积微相的孔渗值统计,发现主河道微相(包括扇根主河道微相和扇中主河道微相)的储层储集物性较好,平均孔隙度值大于10%,平均渗透率值大于20×10-3μ m2。扇根的主槽、辫流线和扇中的辫状河道、水下分流河道微相发育的储层的物性也相对较好,也是油气储集的主要相带。强压实作用导致储层中的孔隙含量降低,孔隙的压实率约为80%。五区岩石中的胶结物堵塞了储层中的孔隙,使储层的孔隙含量降低；因此胶结作用也是导致储层的物性降低的重要因素。另一方面,研究区碎屑岩颗粒、杂基以及填隙物,包括矿物石英与硅质胶结物,发生溶蚀生成次生孔隙,提高了储集层孔隙度、渗透率。微裂缝的发育也大大地提高了储层的物性,尤其是储层的渗透率,直接影响着油气的储集与渗流能力。通过现场的实验研究,五区上乌尔禾组储层必须通过酸化压裂才能取得较好的产量,这也从侧面反映了裂缝对储层渗流的影响至关重要。
[Abstract]:In this paper , reservoir sedimentary facies , diagenesis , reservoir pore structure characteristics , reservoir fine description are studied based on the theory and method of sedimentary petrology , and the reservoir sedimentary facies , logging interpretation data , seismic data and experimental analysis data are used to study the control factors of low porosity and low permeability reservoirs .
The reservoir of Wuerhe Formation in the Wuji area is a conglomerate reservoir , the reservoir characteristics of this kind of reservoir are complex and the research is difficult . There is a non - conformity contact between the formation of Wuerhe Formation and the overlying strata and the underlying strata in the five areas .
Upper Wuerhe Formation can be divided into three sections , namely P3W3 , P3W2 and P3W1 . The sediments of Wuerhe Formation in Wuerhe Formation are generally coarse and mostly glutenite . In addition , there are some sandstone and mudstone . Through the study of the lithology , the color , the sedimentary structure and the logging facies of the study area , the sedimentary facies of Wuerhe Formation in the five areas are determined . According to the sedimentary characteristics of the study area , the alluvial fan is divided into 3 sub - phases and 10 phases ;
There are two sub - phases in the fan - delta facies of the study area , and the six micro - facies are divided into six micro - facies .
In this area , the contact cementation is the main , and the pore type cementation is the next . The compaction effect of the five regions is strong , and the influence of the strong compaction is large . The deformation of the plastic mass and the plastic particles in the study area is mainly caused by the bending deformation of the sand and gravel bodies in the study area .
In this paper , the reservoir of Wuerhe Formation is classified as low porosity and low permeability reservoir .
At the same time , the coarser the rock particles , the stronger the anti - compaction ability , the better the physical properties , the average porosity value is more than 10 % and the average permeability value is more than 20 脳 10 - 3 渭m2 .
Therefore , the cementation is an important factor that leads to the decrease of reservoir physical properties . On the other hand , the study area clastic rock particles , heterostructures and interstitial objects , including mineral quartz and siliceous cements , generate secondary pores , increase the porosity and permeability of reservoir .

【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

【参考文献】