【作者】 朱宏权；

【导师】 沈忠民；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2009， 博士

【摘要】 川西坳陷位于四川盆地西部,是四川盆地西部晚三叠世以来陆相盆地的深坳陷部分,具备多套烃源层、多个烃源区、多期油气生成、多期油气成藏同时又经历了多个构造期调整和破坏,纵向上发育的多套生储盖组合孕育了多层含气层系。“十五”以来,西南油气分公司在川西坳陷中段中深层的天然气勘探中取得了显著的成效,但浅中层勘探程度愈来愈高,勘探难度愈来愈大,同时新场、洛带等浅中层气藏稳产形势严峻。本次论文针对研究区沙溪庙组气藏本身所具有的低孔渗、低丰度以及研究区圈闭形成历史复杂的特点,从基础资料入手,在研究区沙溪庙组层序地层研究的基础上,利用多种方法结合,系统研究了沙溪庙组沉积相特征、对研究区沙溪庙组储层特征分区进行了评价,并进一步综合分析了研究区沙溪庙组天然气成藏主控因素。取得的主要认识及创新性成果如下:(1)在前人研究基础上,通过露头、钻井、地震不同级别层序界面的识别以及层序结构和叠加样式的研究,结合沉积旋回特征,将研究区沙溪庙组划分为3个长期和8个中期旋回,实现了全区沙溪庙组的等时划分对比。(2)在川西地区首次利用泥岩颜色权值研究沉积古地貌。上沙溪庙组沉积中期合兴场-知新场地区泥岩颜色权值较两侧高,说明此时合兴场-知新场地区相对处于氧化环境,沉积水体较两侧浅,即知新场-龙宝梁构造带已开始形成,进一步佐证沙溪庙组沉积时期龙门山向盆内推覆和应力传递过程。(3)运用单因素分析方法,在砂岩厚度、砂地比、泥岩颜色特征、重矿物特征、轻矿物特征以及露头、测井古流向分析的基础上,结合单井相、剖面相、测井相和地震相研究,综合分析了物源的变迁、沉积相展布特征和沉积演化。1)沙溪庙期主要有以龙门山北段变质岩为主要母岩和以龙门山中段花岗岩等酸性岩浆岩为主要母岩的2大物源,古流向分别为北东东向南西西方向和由西北向东南方向。2)沙溪庙期龙门山中段物源沉积体系具贫长石、高石英的轻矿物特征,龙门山北段物源沉积体系相对具富长石、低石英的轻矿物特征;3)下沙溪庙组主要为三角洲前缘-湖相沉积体系,上沙溪庙组主要为三角洲平原(洪泛平原)-三角洲前缘-湖相沉积体系,反映了沙溪庙组沉积时期龙门山逐渐向盆内推覆。(4)将储层沉积物源、沉积速率、古地貌等宏观分析与储层岩石学特征、成岩作用、孔隙演化等微观研究紧密结合,研究了影响储层物性的主要成岩作用类型、强度与沉积特征的关系,初步建立了沙溪庙组相对高孔渗储层的地质预测方法。即古地貌较低的、沉积速率中等、富长石的水下分流河道砂体和河口坝砂体相对更好。(5)分区分层位完善了川西地区沙溪庙组储层参数的测井计算模型,对储层流体响应特征进行了进一步总结,完善了储层的流体判别方法和评价标准。沙溪庙组气层的测井响应特征为“三低二高”,即低自然伽玛、低中子、低密度、高声波、高电阻率。(6)采用盆地模拟软件,恢复出晚白垩世末、早白垩世末、蓬莱镇期末的沙溪庙组古构造形态。从沙溪庙组、遂宁组沉积末到早白垩世末,川西坳陷中段沙溪庙组的构造形态呈南高北低;晚白垩世末,川西中段彭县-崇州地区变成坳陷,孝泉-新场-合兴场-丰谷隆起出现。洛带、中江、大邑等地区在晚白垩世末、早白垩世末、蓬莱镇期末处于继承性高部位。(7)总结了弱形变区浅中层成藏模式-幕式成藏模式,明确指出了幕式成藏模式具有近源成藏的特点,即弱形变区下侏罗统勘探前景更好;完善了烃源断层成藏模式的主控因素,即储层与烃源断层接触面的大小是油气横向运移和聚集的基础,由此提出勘探部署应注重地震异常与断层配置的描述。更多还原

【Abstract】 West Sichuan Depression, located in western Sichuan Basin, is deep depression part of the basin since the Late Triassic. West Sichuan Depression have developed many sets of hydrocarbon source beds, a number of hydrocarbon source area, multi-phase oil and gas generation and accumulation, also have accompanied several tectonic adjustments and destruction episodes, so there were several sets of source-reservoir-cap system in vertical.Since 11th five-year plan, Exploration and Production Research Institute of Southwest Branch Company has achieved remarkable success in deep formation gas exploration in Middle West Sichuan Depression, but as exploration degree and difficulty of shallow and middle formation is getting higher and higher, stable yield situation of shallow gas reservoirs, such as Xinchang, Luodai gas fields is becoming more pessimistical.Shaximiao gas reservoir itself has a low porosity and permeability, low abundance, as well as traps in the study area characterized by the formation of a complex history. Based on sequence stratigraphy studies and combined use of various other methods, the paper systematically studied Shaximiao sedimentary facies characteristics, and evaluated different block reservoir characteristics of Shaximiao formation, then comprehensively analyzed Shaximiao formation accumulation controlling factors.The main access to knowledge and innovative results are as follows:(1) On the basis of previous research, the outcrop, drilling, seismic sequence boundary identification at different levels and sequence structure and stacking pattern studies, combined with sedimentary cycle characteristics of the study area, the Shaximiao formation is divided into 3 long and 8 intermediate-term cycles, and isochronous comparison of Shaximiao formation over whole study region is achieved(2) Depositional paleotopography was studies by using of the color weight value for shale in the West Sichuan depression for the first time. The shale color weight value of central zhixinchang and hexingchang region is higher than that of it both sides in middle period of upper Shaximiao deposition, this indicates the area remain at a relatively oxidizing environment, water depth was relatively shallow, that is, the structural belt has begun to take place, and this also further proved Longmen Mountains to napping toward the basin and Stress Transfer during period of Shaximiao deposition.(3) By single-factor analysis methods, such an the thickness of sandstone, ratio of sand to mud, shale color weight value, heavy and light mineral characteristics, outcrops and logging paleocurrent, as well as by comprehensive analysis on the single-well phase, profile phase, logging phase and seismic facies, the material source changes, sedimentary evolution and distribution of sedimentary facies of Shaximiao formation was systematically studied , the results are as follows:1) There are two primary provenances of Shaximiao formation: one is the northern section of the Longmen Mts metamorphic rocks, and the other is central section of Longmen Mts acid igneous rocks, the two main paleoflow was to the NEE and SE respectively.2)The northern section of Longmen Mts provenance-depositional system was poor feldspar, high-quartz light mineral characteristics during period of Shaximiao , by contrary, the central section of Longmen Mts provenance-depositional system is charactered with feldspar-rich, low-quartz light mineral.3) Two different facies Association were identified in shaximiao formation, the lower Shaximiao formation mainly Consists of prodelta and lacustrine depositional systems, the upper shaximiao formation are formed by the delta plain、prodelta and lacustrine depositional systems. This show that the Longmen Mts thrusts push over towards basin during Shaximiao period gradually.(4) Based on the macro-analysis of provenance, deposition rate, paleotopography and the micro-analysis of reservoir rock characteristics, diagenesis, porosity evolution, the effects of the main diagenetic type,intensity and sedimentary on reservoir quality are studied, and also the geological prediction method about relatively high porosity and permeability is also established initially. The Predicted results show that the underwater distributary channel and mouth bar sands body which are relatively low paleotopography, moderate deposition rate and feldspar-rich are relatively better. (5) Shaximiao reservoir parameters of logging calculation model is improved based on different area and strata in western Sichuan basin, the logging response characteristics of reservoir fluid was further summarized, and reservoir fluid checking Method and evaluation criteria are improved. The logging response characteristics of Shaximiao gas reservoir are low natural gamma, low-neutron, low-density, high-sound waves and high resistivity.(6) By basin modeling, shaximaio formation palaeostructure is recovered at the end of the Late Cretaceous, Early Cretaceous, and Penglaizhen period respectively. From period of the Shaximiao and Suining deposition to the end of Early Cretaceous, the Shaximiao structure shapes was higher in the South than in the north; Late Cretaceous, the Peng xian- Chongzhou region of middle West Sichuan Depression was a depression, and xiaoquan - xinchang - hexiangchang - Feng Gu structural uplift occurred. Luodai-zhongjiang- Dayi regions at the end of Late Cretaceous、Early Cretaceous and Penglaizhen period was the inherited structure high.(7) Accumulation model—episodic accumulation model of the shallow and mid formation with weak deformation is summed up, the model clearly points out that the episodic accumulation model is charactered with near-source accumulation, namely, the Lower Jurassic with weak deformation is the better exploration prospects; Controlling factors of the source -fault of hydrocarbon accumulation mode is improved , namely, size of contact surface between reservoir and source fault is the basic factor that affects lateral migration and accumulation of oil and gas, so exploration should focus on the seismic anomaly and fault configuration description.更多还原