Rub’Al Khali盆地古生界沉積體系及石油地質特征

1、RubAl Khali盆地古生界沉積體系及石油地質特征        RubAl Khali盆地是世界上重要的含油氣盆地之一，由于研究區(qū)前人石油地質工作基礎薄弱，對盆地的構造演化、沉積體系特征、儲層特征知之甚少，因此，在該地區(qū)進行石油天然氣勘探必須對基礎石油地質特征進行研究，從而為在該地區(qū)進行石油天然氣勘探奠定堅實的地質基礎。通過對露頭剖面的觀察、鉆井巖芯的描述和分析、地震資料和測井資料的處理解釋和綜合分析，對研究區(qū)的沉積體系特征和石油地質特征有了新的認識，取得了以下主要成果：1根據(jù)對平衡剖面的分析和研究，將Rub

2、Al Khali盆地構造演化劃分為六個階段：裂陷盆地階段(Pre-Cambrian志留紀Sharawra期)；褶皺、沖斷作用和掀斜作用階段(泥盆紀Tawil-Pre-Unayzah，海西構造運動期)；穩(wěn)定沉積及垂直升降作用階段(石炭早二疊紀Unzazah早白堊世Biyadh期)；擠壓褶皺作用階段(Biyadh期末Aruma期末)；整體掀斜作用階段(Rus沉積后)；盆地萎縮沉積階段(Dammam-Q)。2詳細研究了重點勘探目的層段的沉積體系發(fā)育特征，識別出勘探目的層段的儲層屬于冰川沉積體系、干鹽湖沉積體系、淺海陸棚沉積體系和碳酸鹽巖臺地沉積體系。對上述沉積體系的沉積特征從野外和鉆井資料進行了詳細

3、的研究，指出在冰川沉積體系中儲層的發(fā)育主要為冰水的沉積作用；干鹽湖沉積體系中儲層主要發(fā)育在風成砂和季節(jié)性辮狀河道砂巖中；淺海陸棚中的石英砂巖是研究區(qū)最好的儲集巖石；碳酸鹽巖臺地的儲層主要發(fā)育在白云石化比較強烈的層位。3對研究區(qū)的地震資料進行了重新處理和解釋，根據(jù)對地震資料頻譜分析，設計了適用于研究區(qū)的地質模型，并進行正演模擬，研究了不同厚度、寬度的儲層在地震上的反射特征，砂體的地震反射特征基本為中強反射特征。通過對砂體的正演模擬、常規(guī)地震屬性的優(yōu)化提取、波阻抗反演、約束稀疏脈沖反演、子波提取等方法，確定了儲層的主頻范圍及其對應的地震波形，預測了不同層位的儲層分布。4利用測井資料和試油溫度資料，

4、借鑒鄰區(qū)的地溫資料，對研究區(qū)的地溫場特征進行了研究，結果表明區(qū)域上地溫梯度總體上由北東到西南地溫梯度呈降低的趨勢，MKSR-1井、TKMN-1井和FYDH-1井的的平均地溫梯度分別為2.8/100m、2.5/100m和2.4/100m左右。西RubAl Khali盆地深凹地區(qū)的Qusaiba組地層在下第三系沉積末的構造運動之前經(jīng)歷了最大古地溫，地層古地溫一般不超過198，這一結果為在本區(qū)尋找天然氣和凝析油提供了基礎資料。5對研究區(qū)埋藏史和烴源巖演化史的研究表明，研究區(qū)主要的烴源巖Qusaiba熱頁巖在深凹中進入大量生氣階段，隨演化程度的加大，主力生氣范圍逐漸向東西斜坡方向擴大，生氣率也不斷增大

5、，目前為最大。6分析總結了各目的層段的儲層地質特征和含氣層位的測井曲線特征，根據(jù)鉆井結果和測井曲線對比，確定了不同層位含氣儲層的測井數(shù)值的范圍，總結了研究區(qū)的含油氣系統(tǒng)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