Rub’Al Khali盆地古生界沉积体系及石油地质特征

1、RubAl Khali盆地古生界沉积体系及石油地质特征        RubAl Khali盆地是世界上重要的含油气盆地之一，由于研究区前人石油地质工作基础薄弱，对盆地的构造演化、沉积体系特征、储层特征知之甚少，因此，在该地区进行石油天然气勘探必须对基础石油地质特征进行研究，从而为在该地区进行石油天然气勘探奠定坚实的地质基础。通过对露头剖面的观察、钻井岩芯的描述和分析、地震资料和测井资料的处理解释和综合分析，对研究区的沉积体系特征和石油地质特征有了新的认识，取得了以下主要成果：1根据对平衡剖面的分析和研究，将Rub

2、Al Khali盆地构造演化划分为六个阶段：裂陷盆地阶段(Pre-Cambrian志留纪Sharawra期)；褶皱、冲断作用和掀斜作用阶段(泥盆纪Tawil-Pre-Unayzah，海西构造运动期)；稳定沉积及垂直升降作用阶段(石炭早二叠纪Unzazah早白垩世Biyadh期)；挤压褶皱作用阶段(Biyadh期末Aruma期末)；整体掀斜作用阶段(Rus沉积后)；盆地萎缩沉积阶段(Dammam-Q)。2详细研究了重点勘探目的层段的沉积体系发育特征，识别出勘探目的层段的储层属于冰川沉积体系、干盐湖沉积体系、浅海陆棚沉积体系和碳酸盐岩台地沉积体系。对上述沉积体系的沉积特征从野外和钻井资料进行了详细

3、的研究，指出在冰川沉积体系中储层的发育主要为冰水的沉积作用；干盐湖沉积体系中储层主要发育在风成砂和季节性辫状河道砂岩中；浅海陆棚中的石英砂岩是研究区最好的储集岩石；碳酸盐岩台地的储层主要发育在白云石化比较强烈的层位。3对研究区的地震资料进行了重新处理和解释，根据对地震资料频谱分析，设计了适用于研究区的地质模型，并进行正演模拟，研究了不同厚度、宽度的储层在地震上的反射特征，砂体的地震反射特征基本为中强反射特征。通过对砂体的正演模拟、常规地震属性的优化提取、波阻抗反演、约束稀疏脉冲反演、子波提取等方法，确定了储层的主频范围及其对应的地震波形，预测了不同层位的储层分布。4利用测井资料和试油温度资料，

4、借鉴邻区的地温资料，对研究区的地温场特征进行了研究，结果表明区域上地温梯度总体上由北东到西南地温梯度呈降低的趋势，MKSR-1井、TKMN-1井和FYDH-1井的的平均地温梯度分别为2.8/100m、2.5/100m和2.4/100m左右。西RubAl Khali盆地深凹地区的Qusaiba组地层在下第三系沉积末的构造运动之前经历了最大古地温，地层古地温一般不超过198，这一结果为在本区寻找天然气和凝析油提供了基础资料。5对研究区埋藏史和烃源岩演化史的研究表明，研究区主要的烃源岩Qusaiba热页岩在深凹中进入大量生气阶段，随演化程度的加大，主力生气范围逐渐向东西斜坡方向扩大，生气率也不断增大

5、，目前为最大。6分析总结了各目的层段的储层地质特征和含气层位的测井曲线特征，根据钻井结果和测井曲线对比，确定了不同层位含气储层的测井数值的范围，总结了研究区的含油气系统Rub'Al Khali Basin is one of the important oil-bearing basins. Because of the lack of the knowledge of basin development, characteristics of depositional system and reservoir, the basic petroleum geology has to b

6、e done for further oil and natural gas exploration in the basin. This thesis mainly deals with the basin development, depositional system, reservoir characteristics, diagenesis of sandstone and carbonate based on synthetic analysis of filed work, core description , identification of thin section, wi

7、re line logging, seismic data reprocessing and interpretation. The five well data has been used in the research, three wells located in the research area, the other two wells are adjacent area. Almost 2000km seismic data have been reprocessed and reinterpreted to determine the distribution of reserv

8、oir. Thin sections and SEM analysis has been proceeded to evaluate the history of diagenesis of reservoir rocks. The achievements has been gained mainly as follows:1. According to the study of seismic data, the evoluation of Rub'Al Khali basin could be classified into six stages: rifting and dep

9、ressing stage (Pre-Cambrian to Silurain); folding, faulting and tilting stage (Devonin to Pre-Unayzah); stable deposition and vertical uplift-depress stage (Early Permain to Early Craticeous); squeezing-folding stage; basin tilting stage; basin shrinkage stage.2. The depositional system of explorati

10、on target has been studied in detail. The depositional systems have been classified into glacial sedimentary system; playa sedimentary system; continental shelf system ad carbonate platform system depending on the data analysis of field profiles, core descriptions. The assemblages of rocks both in f

11、ield profile and cores show clearly the sedimentary environments. The reservoir rock developed in glacial system is controlled by the dynamics of glacier melting and continental waves in Sarah Formation. The reservoir rock in playa system is controlled by the distribution of eolian sand dune and eph

12、emeral braided river channel bars in Unayzah Formation. The quartz sandstone developed in continental shelf is the most favorite reservoir rock due to the very good sorting and uniform grain size and porosity in Haradh Formation. Massive dolomitized dolostone is the only reservoir rock in carbonate

13、platform environment in Khuff formatin.3. Reprocessing and interpretation of seismic data exhibit the characteristics of each strata in the basin. Depending on the analysis of frequency and seismic attributes and impedence inversion with well restrict as well, the thickness and distribution of reser

14、voir rocks have been predicted. The results of reservoir simulation revealed main frequency of reservoir which is the most useful methods for predicting the distribution of reservoir, especially in the region of oil and gas exploration with minor geologic data and rare research of geology background

15、.4. Using wire line logging data and the data of testing temperature and gradient of geo-temperature adjacent area, temperature gradient has been studied, which shows the trend of temperature higher in the northeastern part and lower in southwestern part of the basin. The average temperature gradien

16、t is between 2.8/100m and 2.4/100m in well Mksr-1, well Tkman-2 and well Fydah-1. Qusaiba Formation has experienced the highest temperature before the starting of tectonics during lower Tertiary. The highest temperature is near 198. This result confidences the optimistic to the gas and condensate oi

17、l exploration in Rub'Al Khali Basin.5. The study of burial history of source rock clearly shows that the "Hot shale" of Qusaiba Formation has entered to the gas generating peak stage in deep depression of the basin. The range of gas generating is gradually expending along with the matu

18、rity increase of source rock. The productivity of gas generating is now approaching the highest.6. The characteristics of logging data is also summarized for recognizing and assessment the quality of reservoir rocks. Based on the correlation of the results of mud logging and wire line logging data interpretation, the gas reservoir has been recognized. Summarizing the