Experimental research on reservoir sensitivity to stress and impacts on productivity in Kela 2 Gas Field

Kela 2 Gas Field, with high formation pressure (74.35MPa), high pressure coefficient (2.022) and difficulty of potential test and evaluation, is the largest integrated proved dry gas reservoir in China so far and the principal source for West-East Gas Development Project. In order to correctly evaluate the elastic-plastic deformation of rocks caused by the pressure decline during production, some researches, as the experiment on reservoir sensitivity to stress of gas filed with abnormal high pressure, are made. By testing the rock mechanic properties, porosities and permeabilities at different temperature and pressure of 342 core samples from 5 wells in this area, the variations of petro-physical properties at changing pressure are analyzed, and the applicable inspection relationship is concluded. The average productivity curve with the reservoir sensitivity to stress is plotted on the basis of the research, integrated with the field-wide productivity equation. The knowledge lays a foundation for the gas well productivity evaluation in the field and the gas field development plan, and provides effective techniques and measures for basic research on the development of similar gas fields.     

Permo-Carboniferous Radiolarians from the Wupata＇erkan Group, Western South Tianshan, Xinjiang, China

The Wupata‘erkan Group, also called Wupata‘erkan Formation, distributed in the South Tianshan, Xinjiang,China, mainly consists of gray and dark gray fine-grained clastic rocks, interlayered with volcanic rocks, carbonates and cherts. Some ultra-basic rocks (blocks) punctuate the formation. The formation was variously assigned to Silurian-Middle Devonian, Silurian-Lower Devonian, and pre-Devonian, mainly based on Atrypa bodini Mansuy, Hypothyridina parallelepipedia (Brour.) and Prismatophyllum hexagonum Yoh collected from the limestone interlayers, respectively.However, radiolarian fossils obtained from 24 chert specimens of the Wupata‘erkan Group, mainly include Albaillella sp.cf. A. undulata Deflandre, Albaillella sp. cf. A. paradoxa Deflandre, Albaillella cf. A. deflandrei Gourmelon, Albaillella sp. cf. A. indensis Won, Albaillella sp. cf. A. excelsa Ishiga, Kito and Imoto, Albaillella sp. and Latentifistulidae gen. et. sp.indet., are earliest Carboniferous and Late Permian. The earliest Carboniferous assemblage is characterized by Albaillella sp. cf. A. undulata Deflandre, Albaillella sp. cf. A. paradoxa Deflandre, Albaillella cf. A. deflandrei Gourmelon and Albaillella sp. cf. A. indensis Won, and the Late Permian assemblage by Albaillella sp. cf. A. excelsa Ishiga, Kito and Imoto. This new stratigraphic evidence indicates that the Wupata‘erkan Group is possibly composed of rocks with different ages from Silurian to Permian, and therefore, it is probably an ophiolite mrlange. The discovery of Late Permian Albaillella sp. cf. A. excelsa provides more reliable evidence supporting the existence of a Permian relic ancient oceanic basin in the western part of Xinjiang South Tianshan.     

Distribution of Hydrogen and Oxygen Isotopes in Salt Lakes of the Qinghai—Xizang Plateau,China

The Qinghai-Xizang Plateau is an area where a large number of salt lakes are distributed. We have collected several hundred samples of natural waters over the Plateau since 1976 and carried out researches on their hydrogen and oxygen isotopes. The results indicate that the^δD and δ¹⁸O values of the salt lake waters over the Plateau range from −64.1 to +12.4‰ and from −11.19 to +8.62‰, respectively. From the different types of surfaces, ground and lake waters of various salinities it is inferred that the compositions of H and O isotopes in the initial water of Qinghai Lake are^δD=−55.0‰ and {ie336-1}; and those in the original water from the lakes in northern Xizang, are^δD=−116.0‰ and {ie336-2}. Brines in the salt lakes are derived from rain water through prolonged circulation. Oilfield water also makes some contribution to the salt lakes in the Qaidam Basin. Similar slopes of evaporation lines of water isotopes are noticed for the Qinghai Lake area and northern Xizang. This is attributed to the evolution of the isotopes in these water bodies in an environment of middle latitude and high elevation.     

塔里木盆地海相碳酸盐岩与油气

塔里木盆地碳酸盐岩主要分布于台盆区寒武系—奥陶系,它既可以作为油气的储层和源岩,也可以作为油气的盖层或遮挡体。碳酸盐岩主要发育于碳酸盐岩台地相和斜坡相之中,其中开阔台地及台地边缘坡折带的生物碎屑滩和砂屑滩、局限台地的白云岩坪是主要的储集相带。潜山溶孔溶洞型白云岩、石灰岩及礁滩复合体中的生物碎屑灰岩、砂屑灰岩、鲕粒灰岩、礁灰岩以及潮坪白云岩是主要的储集岩。寒武系—下奥陶统、中—上奥陶统都发育有较好的碳酸盐岩烃源岩。根据油气的分布与聚集特点,对碳酸盐岩油气藏作了分类。论述了塔里木盆地碳酸盐岩油气勘探的前景和重要目标。     

Permo-Carboniferous Radiolarians from the Wupata''''erkan Group,Western South Tianshan, Xinjiang, China

1 IntroductionThe Wupata'erkan Group, also called Wupata'erkanFormation (Wang et al., 1990), in the western SouthTianshan, China (Fig. 1), mainly comprises gray and darkgray fine-grained clastic rocks, interlayered with medium-acidic volcanic rocks (andesite and quartz porphyry),carbonates, cherts and variegated tuffaceousconglomerates. The chert in the formation was firstly foundin our field trip along sections of the Qiqi'erjianakesu Riverand Kekebiele Daban. Deformation of the group is…     

塔里木盆地轮南油田TⅢ油组底水块状油藏夹层分布规律研究

用测井、岩性、沉积旋回等理论方法对轮南油田夹层进行划分和对比分析,将轮南油田夹层分为三类:Ⅰ、Ⅱ、Ⅲ型。通过油组纵向、平面对比分析,找到夹层平面、纵向分布规律性,建立轮南油田Ⅲ油组夹层分布模型。这些夹层有以下作用:有利于控制底水上升速度和含水上升,可延长无水采油期;降低井底附近的压力梯度和流动速度,增大水驱波及系数;可以局部改变油水运动规律,因而形成底水托进上升区、油水绕流汇集区和流体经向流动区。     

藏北查桑上三叠统复理石沉积大地构造背景的初步探讨

藏北羌塘地块的构造性质和构造局是中国地学界长期争论的重要问题。这里人迹罕至,研究程度很低,基础地质资料缺乏。这是有关地质问题得不到解决的根本原因之一。本项研究的首要目的也是为该地区的地质研究提供一份基础资料,羌塘地块腹地查桑地区的上三叠统肖茶上涨且,下部为细碧岩、中基性火山岩、玄武质角砾岩来灰岩和大理岩,上部主要为碎屑岩（复理石）和灰岩,我们在肖茶卡组上部的复理石中采集砂岩、粉砂岩样品,进行主量元     

塔里木盆地晚志留世-石炭纪伸展构造的发现及其地质意义

通过精细的地震资料解释,在塔里木盆地中部的满西地区发现晚志留世-石炭纪伸展构造。伸展构造由一系列规模不大的正断层组成,平面上组成两条北东-南西向的左行雁列状正断层带,剖面上构成负花状构造和堑垒构造。根据生长系数计算结果,正断层形成于晚志留世,在泥盆纪和石炭纪持续活动,于石炭纪末停止活动。正断层活动的高峰期为晚志留世。该期伸展构造在塔中和塔北地区也有发育,反映当时塔里木盆地处于区域性伸展构造背景。塔里木盆地晚志留世-石炭纪的伸展构造,是昆仑早古生代晚期（晚奥陶世-中志留世）碰撞造山后构造应力松弛作用的产物。     

塔里木盆地石油地质研究新进展和油气勘探主攻方向

“十五”以来,塔里木盆地石油地质攻关研究取得了多项新进展,主要表现在: 1)发现库车前陆盆地既富气也富油; 2)克拉通区下古生界碳酸盐岩油气富集受储层控制,斜坡带富油; 3)哈得逊周缘东河砂岩具有形成大型地层油气藏的地质条件; 4)塔中地区志留系发育岩性油气藏; 5)下白垩统克孜勒苏群是塔西南喀什凹陷北缘的主要目的层; 6)塔东地区原油裂解气勘探潜力颇大。近期的勘探思路是:以温宿凸起及周缘为重点,加强预探;积极评价轮南奥陶系潜山、塔中多目的层和哈得逊周缘石炭系3个有利区;准备塔西南西部、塔北西部英买力和塔东及塔东南地区3个新领域。