四川盆地东部地区边缘带上古生界构造复杂,对地层格架及地质规律认识不清,尤其对石炭系残余地层分布及沉积相展布认识欠缺,影响了该区的勘探开发.基于区域地质背景,结合新钻井、新三维地震数据及野外露头资料,首次提出了在奉节—云阳一带发育晚古生代持续古隆起(奉节古隆起)的认识;通过地震模型正演,确定了研究区志留系—泥盆系—石炭系地震反射特征,对奉节古隆起进行了刻画;通过研究古地貌控制下的石炭系地层识别及分布特征、构造演化,分析了石炭系油气成藏的条件,对石炭系有利天然气勘探区带进行预测评价.研究认为:奉节古隆起位于开江古隆起东侧约95 km处,与开江古隆起近于平行,整体近南北向,略偏东,其南北轴向长度约79 km,东西向宽度不等,三维区内平均宽度14 km;在开江古隆起和奉节古隆起的联合约束下,研究区的构造演化可以分为5个阶段:泥盆纪低位期、石炭纪低位期、石炭纪海进—高位期、石炭纪海退期和二叠纪海进期;由于奉节古隆起带长期持续演化,可以形成石炭系地层剥蚀带,随着地层埋深加大,在古隆起周缘的石炭系与志留系泥岩侧向对接,在油气充注前形成地层圈闭,后期经过多期构造影响,仍可能在现今的向斜-斜坡区保存为含气圈闭,可以作为石炭系天然气勘探的远景区.该认识为四川盆地东部石炭系天然气扩展勘探新领域提供了支撑.

川东地区石炭系是四川盆地的主要产气层之一.然而,目前其勘探领域仅局限于构造背景的各类圈闭,广阔的向斜区及斜坡区亟需新的地质认识指导勘探.为此,从野外露头、实钻井及地球物理等资料入手,利用线性回归法,恢复了石炭系印支期古构造图,结合石炭系实际气藏分布,探讨了向斜区及斜坡区成藏的有利条件.结果表明:①川东地区石炭系在印支期发育3个地层—构造复合圈闭油藏;②石炭系印支期地层—构造复合圈闭古油藏控制了现今石炭系气藏的分布.结论认为:川东石炭系印支期发育的三个地层—构造复合圈闭气藏的古构造高部位石油充满度高,具备良好的油气成藏条件,是川东石炭系深化勘探的有利区带.

四川盆地石炭系地层是川东地区的主力气层,多年来在盆地内形成了良好的勘探认识.然而盆地边缘受古地理环境的影响,石炭纪沉积时期,盆地北部和东部边缘整体为古地貌高部位,石炭系黄龙组、河洲组和下二叠统梁山组厚度均有较大的变化.显然利用盆地内的研究认识进行盆地边缘的石炭系边界预测必然存在较大误差,导致盆地边缘的许多圈闭尚未落实.针对这一问题,本文以下从正演模拟出发,详细分析石炭系地层反射的变化特征.研究发现石炭系地震反射特征不只是受自身地层厚度的影响,受梁山组厚度影响更大,当厚度10 m以上时,石炭系容易形成波峰反射;当梁山组厚度为1 m时,即使石炭系40 m厚,也不会形成波峰反射.鉴于此,本文建立了不同梁山组厚度的石炭系反射特征总结表,其适用于盆地边缘及盆地内的石炭系勘探.在此基础上,结合其他地质资料和地震预测方法,对以往石炭系剥蚀线进行优化调整,研究结果显示,以往石炭系剥蚀线以外的LT1井南侧存在石炭系地层较厚的区域,具有较大的勘探潜力.

在以往的勘探实践中,采用实钻资料计算地层视倾角方法研究较少.在高陡构造高点区域,地震资料反射质量差,无法有效反映地层实际情况,而测井资料受井况条件影响数据往往不齐全.在高陡复杂构造、储层薄的钻井过程中,由于地面环境制约,实施大斜度井、水平井,常常面临构造高点、钻井轨迹方向地层视倾角资料难以精准预测,导致钻井工程的失误.通过对复杂地质条件下地层视倾角的计算方法研究,可以有效地解决这个难题.以XC1井为例,通过充分利用钻井实施过程中井轨迹实钻资料在实钻条件下,对目的层顶界着陆点的地层视倾角分别采用剖面恢复法、垂深位移法、曲率半径法计算着陆点地层视倾角,研究结果表明:①计算结果与实际较吻合;②该方法的应用有助于高陡复杂构造定向井实施过程中对地质目标靶区的有效控制;③有助于实现大斜度井、水平井工程地质实施水平的整体提升.

有机质石墨化是造成我国部分地区页岩气勘探效果不佳的主要原因之一,目前关于有机质石墨化的程度、深度下限及导致有机质发生石墨化的主要地质原因尚不清楚.为此,以四川盆地川中古隆起及周缘下寒武统筇竹寺组为主要研究对象,利用电阻率测井响应和激光拉曼光谱分析法,对筇竹寺组页岩开展了有机质石墨化表征的电性特征研究;在此基础上,预测了页岩有机质石墨化的深度下限和分布范围,以期为页岩气勘探选区提供依据.研究结果表明:①川中古隆起高部位页岩电阻率测井曲线为正常扁平状特征,有机质拉曼光谱未出现G'峰,未发生有机质石墨化作用;②早寒武世内裂陷区5 200 m以深页岩电阻率测井曲线为低阻特征,拉曼光谱出现G'峰,R.＞3.5％,表明5 200 m以深的有机质已石墨化,但石墨化程度较长宁地区弱;③威远—资阳地区有机质石墨化深度下限值变化大(介于4 000～4 600 m),磨溪—高石梯地区有机质石墨化深度下限值较稳定(5 200m左右).结论认为:①四川盆地川中古隆起大部分地区筇竹寺组页岩的有机质已石墨化,不利于页岩气勘探;②威远—资阳、磨溪—高石梯等构造主体部位为非石墨化区,具有较好的页岩气勘探远景.

A large inherited paleouplift from Pre-Sinian to Early Cambrian, named Xuanhan-Kaijiang paleouplift, has been discovered based on multiple geological information in the eastern Sichuan Basin: firstly, onlap deposition of Upper Sinian Dengying Formation and Lower Cambrian is observed from peripheral zone to central Xuanhan-Kaijiang area from the seismic profile; secondly, Dengying Formation thickness distribution map shows that this formation is thinnest in Xuanhan-Kaijiang area, and thickens towards the surrounding areas; thirdly, terrigenous clastic rock is observed in Upper Sinian Dengying Formation on outcrops in Chengkou County and Wuxi County etc., indicating the development of a paleouplift. The analysis of the characteristics, formation and evolution of the paleouplift reveals that the plane distribution of the paleouplift shows an arched structure, stretching in a north-south trend. The area of the paleouplift is around 16 000 km(2). Vertically, the paleouplift can be divided into three parts: platform in the middle, steep slope in the west and ramp in the east. Originally, the paleouplift was an erosion-type uplift above the water level during the early stage of the Late Sinian; and gradually transformed into deposition-type uplift under water level during the late stage of the Late Sinian to the Early Cambrian. The formation of the paleouplift was controlled by several factors, including basement uplift, intracratonic rift, basement faults and regional uplifting. The paleouplift and its slope areas, favorable for the development of high energy facies and karst weathering reservoirs, are important exploration target areas in the eastern Sichuan Basin in the near future.

Dengying Formation of Sinian is the important gas-bearing strata in the eastern Sichuan Basin.There is important guiding significance for finding the distribution of favorable reservoir by the analysis of the reservoir characteristics and their controlling factors in the eastern Sichuan Basin.The combined macroscopic and micro-scopic methods are adopted for this research on Sinian Dengying Formation in the eastern Sichuan Basin.Based on the lithology characteristics,the scanning electron microscope,the cathode luminescence and some other ex-perimental analyses,some outcrops which are taken from the outcrops and the drilling cores of Dengying Forma-tion are studied for this paper in the eastern Sichuan Basin.The dolomite reservoir of Dengying Formation is studied in the research.The types of the dolomite reservoir formed on the 2nd Member and the 4th Member are mainly the algae dolomite,grained dolomite,powder to fine-grained dolomite and the karst breccia formed in two phase of the weathering crust of 0 to 200 m.The algae dolomite is the main reservoir rock types in the study area among them.The types of reservoir space are very complex,in which primary pore space didn't be found, and there are mainly secondary holes,seams and holes.The types of reservoir space are mainly intergranular dissolved pore,intragranular dissolved pore,secondary intergranular pores and structural fractures and caves, etc,and the intergranular dissolved pore is the main pore types among them in the study area.The development of the dolomite reservoir is mainly controlled by sedimentary environment,diagenesis and tectonic action,etc. The main factor influencing the 2nd Member's reservoir development is sedimentary environment,and another important factor which stores the raw holes is the dissolution diagenetic epigenesis,especially the ancient karsti-fication is the main factor for the 4th Member's reservoir development.Recrystallization and dolomitization play a positive role for the formation and preservation of pore,while the cementation is the main factors of reservoir damage lower's porosity.In addition,Tongwan Movement formed the early group of the large hole,and the later tectonic movement established the particularly complex pore-cave-fracture system in the research area.

Based on outcrops, logging data, seismic data and regional survey reports,the main rocks of the Lower Cambrian Longwangmiao Formation in eastern Sichuan Basin and its adjacent areas car-bonate rocks (i.e.,silt-sized crystalline dolostone,grain dolostone,micritic limstone and grain lime-stone),and some locally-developed large sets of evaporites (gypsum rock and dolomitic gypsum rock) and mixed carbonate-clastic deposits can be seen.Four types of sedimentary facies are identified from <br> northwest to southeast,i.e.,mixed platform,restricted platform,evaporitic platform and open platform, among which,the restricted platform is most widely developed.Generally,all the facies are distributed in a southwest-northeast trending.The mixed platform is mainly distributed in the northwestern study area, the evaporitic platform is mainly distributed on the eastern side of Huayingshan Fault in the western study area,and eastwards,the restricted platform and the open platform are developed respectively.

Based on analysis of 40 wells data of thin-section observation,logging,well logging,oil production test and rock core and scan electricitymicroscope observation,The results show that the rocks of reservoir include the oolite dolostone,Crystal-dolostone,oolite limestone,micrite-limestone,atc.The reservoir space include intergranular pore,intragranular pore,intercrystal pore,(tectonic and corrosion)fracture,atc.The reservoir pore include the pore,fracture-pore,pore-fracture,fracture,which compound appear in the reservoir.The reservoir physical features is relatively bad,include the low pore-low permeate,low pore-high permeate appear in the area that develop the fracture.reservoir controlled by the sedimentary facies,dolomitization,solution,tectonic,which commonly control the reservoir distribute.It is very important that the fracture controlled by tectonic is the key factor of scale reservoir in the south of kaijiang-liangping ocean trough.

There are many important oil-gas resources in Feixianguan Formation of northeast Sichuan.The south sector of LiangpingKaijiang ocean trough is very extensive and has many important potential oil-gas resources.Based on an analysis of rock core,field cross section,logging,well logging and thin-section observation data,the authors studied the sequence-lithofacies paleogeographic characteristics of Feixianguan Formation in south sector of Liangping-Kaijiang ocean trough.The result indicates that the sedimentary model of the study area belongs to the attached land platform which includes the platform,sloping ground,and residual ocean trough facies.Based on the sequence interface identification,the authors divided the Feixianguan Formation into three third-level sequences,namely SQ1,SQ2,and SQ3.Each of the sequence is divided into three system tracts,i.e.,TST,EHST,and LHST.With the system tract as the unit of the sequence-lithofacies paleogeographic map,this paper discusses in detail the lithofacies paleogeographic characteristics and evolution of various sequence system tracts.With the reduction of the ocean trough,the attached land platform expanded gradually,the platform edge beach and intra-platform beach gradually advanced to the ocean trough,which controlled the reservoir distribution.

在三叠世早期,四川盆地继承了晚二叠世的海盆特征.在川东地区飞仙关组和长兴组之间没有明显的沉积间断,但二者岩性存在差异.川东地区飞仙关组的实钻表明,在以开江--梁平地区为中心,形成了一个不对称的凹陷区域.以这一凹陷区为界,其两侧沉积环境和地层特征有明显的不同.以现阶段的勘探认识和拥有的资料及目前的研究结果,整个川东地区飞仙关组的沉积环境及演变是在碳酸盐岩台地上的变化,其沉积模式为"浅海碳酸盐岩台地"模式.这种古地理格局控制了飞仙关组的沉积特征,以至于以中央凹陷区为界,在两侧形成了不同的储层类型和展布特征,不同类型的鲕滩储层分布受沉积相的控制明显并有一定的层位性.