【作者】 杜秀芳；

【导师】 陈昭年；

【作者基本信息】 中国地质大学（北京） ， 石油与天然气工程， 2003， 硕士

【摘要】 柴达木北缘块断带为柴达木盆地一级构造单元，面积约3万km²。前人对此地区的盖层保存条件评价较少，作者利用现有勘探资料，如地震剖面、测井资料、钻井资料和样品分析等，结合沉积学原理和油气保存原理，对柴北缘封盖层进行了综合评价。划分出封盖层的类型和规模，取得的重要成果和创新之处主要体现在： 1、系统分析了油气封闭机理，指出了油气盖层封闭油气主要为毛细管封闭和浓度封闭，水动力封闭和压力封闭是毛细管封闭的特殊表现形式，本质上其机理仍属于毛细封闭。 2、根据沉积学原理，分析了沉积、构造及海平面变化对封盖层的影响程度，划分出区域盖层和局部盖层，并绘出封盖层分布等厚度图。 3、在该课题研究中，针对柴北缘特定的石油地质条件，在油气封盖层评价过程中，利用高温高压模拟地层条件突破压力测定技术，测定高温高压条件下样品的物性参数—突破压力，同时进行覆压条件下孔隙度及渗透率的测定，提高了样品参数的精确度。 利用高温、高压模拟条件下突破压力测定技术与方法，并结合常规及其它模拟技术对样品进行了封盖能力模拟，系统分析了泥质岩盖层封盖能力及其影响因素。 4、结合柴北缘区域地质特点，建立了封盖层评价标准。利用模拟试验技术分析盖层的封盖能力，结合盖层宏观展布特点分层组对盖层进行评价，并结合生储盖组合关系、断裂发育程度及圈闭条件等，综合评价封盖性能。 5、利用LOGES测井处理系统研究单井盖层分布状况，储、盖层组合情况，划分有利储、盖组合。 6、盖层有效性研究：研究盖层从沉积到形成演变的地质历史发展过程，地史中盖层的封闭能力与油气源岩排烃历史、储层演化、圈闭形成以及油气运移、聚集和保存条件的演变等的匹配关系。 7、通过综合分析认为，柴北缘发育下干柴沟组（E₃¹、E₃²顶）和上干柴沟组N₁两套区域盖层，其余几套局部发育优质盖层，显示该区具有较好的油气保存条件。 8、通过盖层综合评价认为：柴北缘地区第三系缺乏相对稳定的深湖—半深湖相优质盖层，滨浅湖相泥岩相当发育。有利盖层分布区主要分布在昆特依坳陷、鄂博梁Ⅱ号—鸭湖构造带、鄂博梁Ⅰ号—葫芦山构造带、伊克雅乌汝凹陷、冷湖构造带和马海—南八仙构造带。 9、从油气有利聚集带出发，冷湖地区以冷湖三、四、五号，马仙隆起以南斜坡为最有利勘探目标区。更多还原

【Abstract】 The Northern Qaidam Basin is one of the structure cells in the Qaidam Basin where located in Qingzang Plat., with an area of 3 X 104km2. This paper presents a systematic research on oil and gas sealing conditions of the Northern Qaidam Basin based on the seismic profiles, well logs, drilling, sample analyses, mechanism of sediment and the theory of oil and gas preservation.Based on the previous work, the main results are as follows:1. The sealing mechanism can be classified as capillary sealing and concentration sealing after systematical analyzing the sealing mechanism of the sealing formation. In fact, both the pressure sealing and the hydraulic sealing are belong to capillary sealing, they are special forms of capillary sealing;2. According to the sedimentary mechanism, the effects of sedimentary environments, structural movements and changes of the sea level on the development of the cap rock were analyzed, the distribution regularity was obtained;3. The high pressure and high temperature experimental tests have been done to measure the breakthrough pressure of the cap rock. According to the special and routine results, the sealing capacity of the mudstone at reservoir conditions and the affecting factors were analyzed. The evaluation criterion of the cap rock was established, combining the geology feature of the Northern Qaidam Basin;4. A method of synthesized evaluation on sealing capacity was proposed, the sealing capacity of cap rocks by use of simulation test technology was analyzed, and the cap rock was evaluated by means of the feature of the cap rock distribution;5. By means of Well Log Evaluation System, the cap rock distribution and combining reservoir sealing of single well were analyzed;6. The comprehension sealing capacity of each formation group has been studied by using the physical properties and the formation distribution. Study on the package relationship of source rocks, reservoir and cap rocks, the oil shows, the development of faults, and the development of traps, the prospecting area have been predicted in the Northern Qaidam Basin;7. The sealing capacity is better with two sets of area cap rock and several sets of regional cap rock. The most important regional cap rocks of the Northern Qaidam Basin are the mudstones of upper and lower Ganchaigou Formation. The mudstones of upper Youshashan Formation are the local cap rocks for the upper secondary reservoir. The argillaceous rocks of each formation are the direct or indirect cap rocks for the underlying reservoirs and have good sealing qualities;8. The most favorable regions for cap rocks are evaluated. The comprehensive result is that the Lenghu structural belt and the Nanbaxian-Mahai structural belt are the best ones of oil and gas accumulation conditions.更多还原