Reconstruction of the Yangtze Ramp during Floian to Darriwilian(Ordovician)in South China:Its Morphology,Controlling Factors and Significances

A robust stratigraphic framework and a coherent depositional ramp model for the Zitai,Dawan,Meitan and Ningkuo formations of Floian–Darriwilian age(Early–Middle Ordovician)in the Yangtze(Daoba,Xiangshuidong,Daling,Gudongkou and Honghuayuan sections)and Jiangnan regions(Nanba section)was created based on lithofacies and major element analysis.Three siliciclastic(LF1–3)and six carbonate(LF4–9)lithofacies are recognized representing sediments that were deposited in mixed siliciclastic and carbonate ramp environment.The intensity of mixed sedimentation and terrigenous input were evaluated using the elemental proxies Intensity of Mixed sedimentation(IM)and Aluminum Accumulation Rate(Al AR),as well as their mean values during certain time intervals.Mixed sediments are most well-developed along the marginal Yangtze region,strongly impacted by recurrent influx of westerly derived terrigenous materials in response to global eustatic changes and regional tectonic movements,shaping the gently southeast-dipping morphology.Regular terrigenous influx resulted in periods of enhanced primary productivity on the Yangtze Ramp as evidenced by matching biodiversity peaks in planktonic organisms,i.e.,chitinozoans and acritarchs.Brachiopods and other shelly fauna were also able to proliferate as new niches developed along the gently dipping ramp floor with substrate changes.The biodiversification patterns suggest that terrigenous influx controlled in part by regional tectonics played a more important role than previously thought in the development of Great Ordovician Biodiversification Event in South China.

Formation conditions and reservoir-forming models of the Ordovician buried hill reservoirs in the Jizhong depression

The buried hill in the Jizhong depression contains abundant petroleum reserves and are important production areas.The Ordovician buried hill has restricted the discovery of new oil and gas exploration targets because of its strong reservoir heterogeneity and complex reservoir-controlling factors.Based on a large volume of core,thin section,logging,seismic,and geochemical data and numerous geological analyses,the reservoir-forming conditions and modes were systematically analyzed to guide the exploration and achieve important breakthroughs in the Yangshuiwu and Wen an slope buried hills.The study revealed that three sets of source rocks of the third and fourth members of the Shahejie Formation from the Paleogene and Carboniferous-Permian were developed in the Jizhong depression,providing sufficient material basis for the formation of buried hill oil and gas reservoirs.The reservoir control mechanism involving the three major factors of“cloud-karst-fault”was clarified,and karst cave,fracture fissure-pore,and cloud pore type reservoir models were established,thereby expanding the exploration potential.Controlled by the superposition of multi-stage tectonic processes during the Indosinian,Yanshanian,and Himalayan,two genetic buried hill trap types of uplift-depression and depression-uplift were formed.Based on the analysis of reservoir-forming factors of the Ordovician buried hill,three buried hill oil and gas reservoir-forming models were identified:low-level tectonic-lithologic composite quasi-layered buried hill,medium-level paleo-storage paleo-block buried hill,and high-level paleo-storage new-block buried hill.Comprehensive evaluations indicate that the reservoir-forming conditions of the low-level tectonic-lithologic composite quasi-layered buried hill in the northern portion of the Jizhong depression are the most favorable and that the Sicundian and Xinzhen buried hills are favorable areas for future exploration.

Paleoenvironment reconstruction of the Middle Ordovician thick carbonate from western Ordos Basin, China

Reconstructing paleoenvironments has long been considered a vital component for understanding the development and evolution of carbonate reservoirs.The Middle Ordovician Period is considered the archetypical greenhouse interval,and also a critical period in biological evolution.The Middle Darriwilian isotope carbon excursion has been observed in many areas of the world and may be related to the biological explosions caused by decreases in the temperature.The thick carbonate rocks in the fifth member of the Middle Ordovician Majiagou Formation in the Dingbei area of the Ordos Basin were chosen as an example,based on the concentration of major,trace and rare earth elements as well as C,O and Sr isotopic analyses,the paleoenvironment was reconstructed.And its impact on natural gas exploration was analyzed.The results show that the seawater paleotemperature was 29℃,suboxicanoxic paleoredox conditions were observed,and the seawater paleosalinity was high.A large number of plankton in the biological explosion caused a rapid increase in the total organic carbon in carbonate rocks,which provided natural gas as supplemental source rocks.Affected by early meteoric water,the dissolution of gypsum laid the foundation for high-quality reservoirs,and the residual gypsum also further preserved natural gas.This study provides new data for the paleoenvironment and a theoretical basis for further natural gas exploration.

Enlightenment of calcite veins in deep Ordovician Wufeng-Silurian Longmaxi shales fractures to migration and enrichment of shale gas in southern Sichuan Basin, SW China

The relationship between fracture calcite veins and shale gas enrichment in the deep Ordovician Wufeng Formation-Silurian Longmaxi Formation (Wufeng-Longmaxi) shales in southern Sichuan Basin was investigated through core and thin section observations, cathodoluminescence analysis, isotopic geochemistry analysis, fluid inclusion testing, and basin simulation. Tectonic fracture calcite veins mainly in the undulating part of the structure and non-tectonic fracture calcite veins are mainly formed in the gentle part of the structure. The latter, mainly induced by hydrocarbon generation, occurred at the stage of peak oil and gas generation, while the former turned up with the formation of Luzhou paleouplift during the Indosinian. Under the influence of hydrocarbon generation pressurization process, fractures were opened and closed frequently, and oil and gas episodic activities are recorded by veins. The formation pressure coefficient at the maximum paleodepth exceeds 2.0. The formation uplift stage after the Late Yanshanian is the key period for shale gas migration. Shale gas migrates along the bedding to the high part of the structure. The greater the structural fluctuation is, the more intense the shale gas migration activity is, and the loss is more. The gentler the formation is, the weaker the shale gas migration activity is, and the loss is less. The shale gas enrichment in the core of gentle anticlines and gentle synclines is relatively higher.

Types and microstructures of pores in shales of the Ordovician Wulalike Formation at the western margin of the Ordos Basin, China

Shale samples from the Ordovician Wulalike Formation at the western margin of the Ordos Basin are studied to define the types, microstructures and connectivity of pores as well as the relationships between the pore structures and gas content of the samples by using experimental techniques such as high-resolution field emission scanning electron microscopy (FESEM), mercury injection capillary pressure (MICP), low-temperature nitrogen adsorption (LTNA), CO_(2) adsorption, and focused ion beam scanning electron microscopy (FIB-SEM). The results show that the shale has 10 different lithofacies, typical mixed sedimentary characteristics, and poorly developed pores. The reservoir space mainly consists of intercrystalline pores, dissolution pores, intergranular pores, and micro-fissures, with organic pores occasionally visible. The pore size is mostly within 0.4–250 nm range but dominated by micropores and mesopores less than 20 nm, with pore numbers peaking at pore sizes of 0.5 nm, 0.6 nm, 0.82 nm, 3 nm, and 10 nm, respectively. The pores are poorly connected and macropores are rarely seen, which may explain the low porosity and low permeability of the samples. Samples with high content of organic matter and felsic minerals are potential reservoirs for oil and gas with their favorable physical properties and high connectivity. The pores less than 5 nm contribute significantly to the specific surface area and serve as important storage space for adsorbed gas.

陕西省煤矿典型水灾隐患特征及治理技术

陕西省煤炭资源丰富,2022年煤炭产量达7.46亿t,是我国主要产煤省份之一。由于全省煤矿区地质及水文地质条件差异明显,煤矿水灾类型多样,随着近年煤炭开采强度的增大,水灾事故时有发生,防治水形势较为严峻。以煤炭赋存条件为基础,系统总结区域水文地质结构特征,界定典型水灾类型及各类水灾影响区域分布,论述典型水灾的形成机理及特征,并提出了相应的防控技术。研究表明:(1)陕西省主要煤炭产区分为陕北、黄陇、渭北三大区,陕北侏罗纪煤田主要有顶板松散沙层水灾隐患、厚层砂岩水灾隐患、溃水溃沙灾害,局部区域分布有烧变岩对煤矿造成水灾隐患;黄陇煤田主要受顶板巨厚砂岩水灾隐患、离层溃水隐患、泥砂溃涌灾害隐患威胁;陕北石炭—二叠纪煤田和渭北煤田,主要受到煤层底板奥陶系灰岩水灾隐患威胁。(2)陕北侏罗系煤田顶板水灾隐患主要为顶板含水层受开采导水裂隙带扰动形成,导水裂隙波及砂岩含水层或松散沙层可形成持续大流量涌水,部分区域充水强度较大,在短时间水量较大超过排水系统能力时造成顶板水灾,在薄基岩区域垮落带直接导通松散沙层时可转变为溃水溃沙灾害,导水裂隙带影响到烧变岩富水区域时可形成瞬时水量大且持续的烧变岩水灾;黄陇煤田顶板巨厚砂岩含水层受采动导水裂隙带波及形成高强度持续涌水并可能形成顶板水灾,当含水层下部隔水层厚度较大时,可能形成离层溃水灾害,当近煤层顶板岩层松软遇水易崩解时可转变为泥砂溃涌灾害;陕北石炭—二叠纪煤田和渭北煤田,煤层开采底板扰动破坏带或断层等构造导通奥陶系灰岩含水层时,会引发极为严重的底板突水灾害,该类灾害具突发性强、瞬时水量大的特征。(3)各区域的顶板水灾隐患治理技术主要包括钻孔疏泄、注浆治理、开采参数控制等,底板水灾隐患治理技术主要包括区域注浆加固及封堵等;烧变岩水灾隐患主要采取帷幕注浆与钻孔探放有机结合的防治技术。

塔里木盆地北部奥陶系海相碳酸盐岩断溶体油藏成因类型及特征再认识

前人提出的“断溶体”油藏概念,现已成为海相碳酸盐岩油气藏勘探开发的新目标、新类型。但断溶体油藏与传统的风化壳型喀斯特油藏有显著差别,断溶体储集体类型、结构特点也存在差异。研究断溶体溶蚀作用和构造破裂作用的差异性,将断溶体划分为过溶蚀残留型、破碎+强溶蚀型和强破碎+弱溶蚀型3种类型。研究表明不同成因类型的断溶体油藏,其溶蚀程度、缝洞规模、累产油量、地层能量和缝洞间连通性差异明显。过溶蚀残留型油藏的分布受风化壳不整合面及断裂带的纵向溶蚀作用控制。破碎+强溶蚀型及强破碎+弱溶蚀型油藏的形成和分布与不整合面的发育和构造位置关系不大,主要受溶蚀断裂带“破碎+溶蚀程度”控制,在溶蚀断裂带核部发育规模较大的洞穴,向两侧逐步发育裂缝-孔洞型、裂缝型储层。

北祁连冷龙岭地区上奥陶统扣门子组的时代归属——来自牙形石的证据

本文首次报道了北祁连冷龙岭地区上奥陶统扣门子组牙形石,共识别鉴定出牙形石5属,9种,其中3个未定种,根据牙形石的分布规律,建立了1个牙形石组合:Aphelognathus grandis-Panderodus gracilis组合。笔者通过对研究区牙形石组合与国内外其他地区相同层位的牙形石带对比,并结合扣门子组其它古生物化石资料,将北祁连冷龙岭地区扣门子组的时代重新厘定为晚奥陶世桑比期—赫南特期中期,相当于中国地层年表的艾家山期晚期—钱塘江期中期。

鄂尔多斯盆地中-上元古界—下古生界热演化程度:来自伊利石结晶度及伊蒙混层的指示

由于缺乏有效的古温标,对鄂尔多斯盆地中-上元古界—下古生界热演化程度一直以来了解十分有限。本文通过对盆地内20余口钻井中-上元古界—下古生界开展自生伊利石结晶度和伊蒙混层系统性测试,试图从新的角度分析盆地中-上元古界—奥陶系热演化程度及分布规律。结果表明:盆地不同部位伊利石结晶度与深度关系存在明显的差异,整体具有随深度增大而减小的趋势,主要受控于古埋深及古地温梯度。盆地沉积盖层伊利石结晶度普遍大于0.25,未达到绿片岩相浅变质阶段;盆地下古生界奥陶系伊利石结晶度大于0.42,表明处于成岩演化阶段;寒武系样品结晶度略小于奥陶系,整体处于成岩带中-晚期到极低级变质作用阶段;中元古界伊利石结晶度相对更低,对应热演化程度更高。此外,我们对比了伊利石结晶度和等效镜质体反射率分别恢复的地层最大古地温结果,两者在误差范围内基本一致,表明这一方法对研究我国古老地层热演化程度具有明显的可行性。

塔里木盆地富满地区一间房组颗粒滩类型及分布

为明确富满地区中奥陶统一间房组颗粒滩类型及其分布,应用岩心、岩石薄片、碳同位素、测井、地震等资料,对其沉积相及其展布开展了研究。研究区一间房组沉积相类型可分为斜坡—盆地、台地边缘和开阔台地,后两者是颗粒滩的主要发育区;颗粒滩包括砂屑滩、鲕粒滩、生屑滩、过渡类型等,厚度占比普遍大于80%,部分井区大于90%,具浅颗粒滩化,其分布受快速海侵及缓慢海退背景下侧向迁移为主的沉积方式控制。开阔台地大面积分布的砂屑滩及生屑砂屑滩具备良好的储集性能,可作为下一步油气勘探的重要领域。

塔里木盆地麦盖提斜坡罗探1井奥陶系断控岩溶新类型油气藏勘探突破及意义

塔里木盆地麦盖提斜坡罗探1井在奥陶系碳酸盐岩获得勘探新突破,是麦盖提斜坡奥陶系断控岩溶新类型油气藏的首次勘探突破,标志着斜坡区发现一个重要的战略接替领域。结合区域钻井、测井、地震等资料,开展罗探1等井分析化验资料的综合分析,对麦盖提斜坡奥陶系碳酸盐岩的成藏条件进行再认识。麦盖提斜坡奥陶系碳酸盐岩断控岩溶储层的形成主要与走滑断裂活动相关,是麦盖提斜坡三类主要成储模式之一;麦盖提斜坡目前已发现油气均来自寒武系玉尔吐斯组烃源岩,基底古构造控制了下寒武统的沉积和烃源岩的分布;斜坡区存在加里东期、海西期—印支期和喜马拉雅期3期油气充注成藏过程,烃源岩、古构造演化及通源断裂控制油气复式聚集成藏,断裂活动期次、断穿层系决定了油气富集层系与油气藏性质。麦盖提斜坡奥陶系走滑断裂十分发育,延伸距离累计可达1000km以上,控制了断控岩溶储层和油气藏的分布,平面上具有明显的分区特征,资源规模大、可部署性强,展示出巨大的勘探潜力,是塔西南地区规模油气勘探发现和战略接替的重要现实领域。

柴北缘茶卡北山伟晶岩型锂铍矿变质围岩时代及原岩特征

茶卡北山锂铍矿床位于青海南山西部,区域构造上处于宗务隆山陆缘裂谷带东段。矿体赋存于花岗伟晶岩脉中,围岩为低角闪岩-高绿片岩相变质岩组合,该套变质岩作为锂铍矿体围岩,对于探讨柴北缘锂铍矿成矿规律及成矿预测具有重要意义。依据岩石组合,将其单独厘定为茶卡北山片岩岩组,通过对片岩开展锆石阴极发光图像特征研究和锆石U-Pb(LA-ICP-MS)测年,限定形成时代为南华纪—奥陶纪,为宗务隆山陆缘裂谷带新发现的新元古代—早古生代地层。锆石Hf同位素分析结果显示,εHf(t)值分布范围在-19.62~-3.07之间,表明源区岩石源自古元古代—新太古代上地壳物质的部分熔融。片岩SiO_(2)含量介于61.33%~70.57%之间,FeO含量为3.58%~5.13%,TFe2O_(3)含量为5.2%~7.95%,MgO含量为1.89%~4.95%。球粒陨石稀土元素配分曲线表现为右倾,重稀土元素曲线趋于平缓,具有弱Eu亏损和轻稀土元素富集特征。微量元素富集Th、U、Nd、Zr、Hf、Nb、Ti等高场强元素,亏损Ba、Sr等亲石元素。综合岩石年龄和地球化学特征,认为茶卡北山片岩形成于新元古代—早古生代弧后盆地环境,原岩遭受弱风化剥蚀作用,化学组分稳定,确定为泥质砂岩,物质主要来源于岛弧环境的长英质火成岩,构造环境为大陆岛弧,与矿区含锂铍矿伟晶岩脉源区一致。

鄂尔多斯盆地西缘中-上奥陶统烃源岩的形成环境、成烃生物及岩矿特征

鄂尔多斯盆地西南缘奥陶系发育与盆地本部奥陶系沉积特征截然不同的沉积层,其中西缘的中-上奥陶统烃源岩发育较好的海相烃源岩层。近期,通过对该套烃源岩形成的构造—沉积环境、成烃生物特征及烃源岩层岩矿特征等方面的分析,表明有利烃源岩的发育受多种因素的控制,其分布具有一定的规律性:1)盆地中-上奥陶统主力烃源岩主要形成于沉积水体不断加深的构造沉积背景,其中沉积水体能量较弱,陆源碎屑注入相对较慢的半深水斜坡环境最有利于富有机质烃源岩发育;2)西南缘奥陶纪虽然生物类型多样,种群繁盛,但能形成重要烃源岩层的母源生物(生烃母质)却多以浮游生物、疑源类(微体藻类)及蓝细菌为主,相对还原的介质环境和适宜的沉积埋藏速率对有机质的有效保存也起重要的控制作用;3)X-衍射物相分析及扫描电镜等微观研究显示,主力烃源层段所谓“泥页岩层”的造岩矿物类型仍以石英、长石类为主,次为伊利石类黏土矿物与碳酸盐矿物,少量黄铁矿等;黏土矿物及黄铁矿含量与有机质丰度关系密切。

塔里木盆地塔东地区油气地质条件与有利地质体资源潜力

大庆油田塔东探区主体位于塔里木盆地台盆过渡区满西台缘带,勘探程度低,资源潜力大。勘探主要集中在古城地区,未获规模突破。近年来通过老井复查、构造-岩相古地理研究,明确了台缘带油气基础地质条件,落实了成藏有利区带,拓展了塔里木盆地寒武系勘探新类型。结果表明:塔东探区发育玉满裂陷、玉都裂陷槽盆相,斜坡陆棚相等多套烃源岩;寒武系—中下奥陶统台缘带高能礁滩继承发育,多组走滑断裂控储、控藏、控富集;“黑被子”泥岩、“白被子”膏岩2套区域盖层分布广泛,源、储、盖紧密配置,具备规模成藏条件;纵向上,油气受走滑断裂及区域盖层控制,主要分布在中下奥陶统碳酸盐岩地层;横向上,以玉满、玉都裂陷槽为中心,油气规模富集;玉满奥陶系鹰山组上段断溶体、鹰山组下段礁滩-断溶复合体成藏条件优越,发育凝析气藏,是塔东最现实的效益勘探领域;寒武系盐下礁滩体、断控丘滩带源、储、盖配置好,资源潜力大,可作为增储上产的接替领域。塔东探区多领域均展现出万亿立方米的气资源规模,有望快速建成大庆油田稳油增气的重要基地。

鄂尔多斯盆地西北缘奥陶系克里摩里组等深流沉积

等深流沉积是深水沉积中的常见类型之一。古代地层记录中等深流沉积的鉴别及形成机理研究相对薄弱。在鄂尔多斯盆地西缘奥陶系克里摩里组发现了一种新的等深流沉积类型,即透镜状等深流沉积。研究表明:(1)研究区发育4种岩相及组合。岩相1为透镜状泥晶灰岩,岩相2以透镜状粉晶灰岩为主,岩相3为透镜状泥晶及亮晶方解石胶结砾屑-砂屑灰岩,岩相4以层状砾屑灰岩最为常见。(2)透镜状泥晶、粉晶及砾屑-砂屑灰岩相单层厚度相对较小,波状界面,呈透镜状,局部见泥质纹层、条带及斑点,粉晶方解石多呈斑块状,整体呈细—粗—细沉积序列,为等深流持续作用而成;层状砾屑灰岩相中砾屑见叠瓦状构造,局部见倒“小”字排列,可能与风暴相关。(3)碳氧同位素反映相对海平面及古温度具有2个升高—降低旋回及1个持续上升半旋回。(4)研究区等深流为相对低能的温盐环流。等深流活动强度与海平面升降、盐度变化呈正相关。(5)从下至上,等深流活动逐渐加强,局部存在短暂极强现象,并可能受风暴影响。

塔里木盆地塔河油田逆冲背斜区奥陶系古暗河系统发育特征

塔里木盆地塔河油田古暗河系统研究尚处于初始阶段,主要从暗河的深浅分布、结构样式等特征开展暗河洞穴的划分,较少从构造、断裂、古地貌、地下水位等地质方面综合分析复杂暗河系统的空间发育规律,致使暗河的主次从属关系、空间叠置样式、原始连通关系难以厘清,从而制约了塔河油田开发后期的综合治理研究。为了明确塔河油田主体区逆冲背斜区奥陶系古暗河系统发育特征,利用构造断裂解析、古地貌恢复、地震属性刻画、纵断剖面解读等方法进行了S67井区古暗河的类型识别、系统划分和地质成因研究,尤其首次识别并剖析了潜流回流暗河。结果表明,S67井区处于塔河主体区岩溶台原南缘的低地势区,发育幅差较小的峰丛洼地、溶丘洼地,地表水系下切深度较浅;逆冲背斜为低角度逆冲推覆构造样式,逆冲背斜之上的网格状断裂为多层状暗河系统提供有利溶蚀通道。研究区奥陶系发育相对独立的、树枝状结构的地下水位暗河系统和潜流带暗河系统,地下水位型暗河可分为主干型、支流型和废弃型,潜流回流暗河可分为上升型、对称型。控制逆冲背斜区古暗河发育的主要因素有古地貌、地下水位、逆冲背斜构造和次级断裂网络等。

塔里木盆地F_(Ⅰ)17走滑断裂北段奥陶纪差异变形机制

为明确走滑断裂对碳酸盐岩油气成藏的作用,基于三维地震资料,分析F_(Ⅰ)17走滑断裂北段的发育特征与构造变形过程,结合地质建模,开展走滑断裂形成及演化的砂箱物理模拟。研究区内的F_(Ⅰ)17走滑断裂可分为南、北2段,南段为近北东—南西走向,主要发育雁列式断裂,奥陶纪一间房组整体以隆升为主,垂向上的变形幅度较大;北段为近北北东—南南西走向,主要发育线性走滑断裂,在奥陶纪一间房组变形微弱,局部地区可见地层微幅度下掉。砂箱物理模拟实验结果表明:线性走滑断裂的主位移带上会形成一系列隆起带,而走向偏转的走滑断裂在南段形成一系列隆起带,在北段则表现为地层下掉;在同一应力条件下,走滑断裂初始走向的差异会导致断裂受力发生变化,进而影响其演化过程。F_(Ⅰ)17走滑断裂南段的压隆段应力更加集中,局部裂缝和溶洞更发育,油气更为富集,油气勘探效果优于北段。

阿尔金-东昆仑造山带铜镍矿成矿地质条件与找矿前景

基于阿尔金-东昆仑造山带基性-超基性岩分布和铜镍矿找矿勘查进展,梳理该区铜镍矿产特征和成矿规律,指出下一步找矿方向。研究显示,阿尔金-东昆仑造山带铜镍矿成矿期分为4期:元古代(1 118 Ma)、奥陶—泥盆纪(465~405 Ma)、二叠纪(270 Ma)、三叠纪(244 Ma),元古代铜镍成矿作用主要与热液作用有关,后3期主要与岩浆熔离作用有关,并有热液作用的叠加。奥陶—泥盆纪幔源岩浆活动强烈,多分布于阿尔金南缘断裂及次级断裂附近,岩体岩相分带清楚,岩浆分异充分,成矿前景大,是阿尔金-东昆仑地区寻找铜镍硫化物矿床的优选方向。受构造作用影响,该期基性-超基性岩与蛇绿岩套镁质橄榄岩共存同一空间,需加强对该时期铁质基性-超基性岩体的综合评价。二叠—三叠系岩体多以辉长岩为主,已发现的超镁铁质岩石赋存有铜镍矿化体,为该区寻找铜镍矿的次要方向。

哈拉哈塘油田塔河北区块奥陶系断裂发育特征及断控区储层类型与分布预测

塔里木盆地哈拉哈塘油田奥陶系碳酸盐岩储层非均质性复杂,亟需开展评价预测研究。本文基于哈拉哈塘油田地质及地震资料,开展了碳酸盐岩缝洞储层归位、储层空间展布、储层与断裂的匹配关系、井间连通性研究。在此基础上,依据实钻、测录井资料及生产动态分析,开展了断控区碳酸盐岩储层缝洞雕刻。研究结果表明:哈拉哈塘油田断裂系统发育包括加里东早-中时期、加里东晚期-海西早期、海西晚期、燕山期4个阶段;断裂走向和断裂发育的多期次性是断裂系统的通源性的主控因素;断块水平滑移的增大将使走滑断裂具有较好的连通性;断裂的平面扩溶宽度受断裂活动强度以及深部通源分支断层发育程度控制。此外,为明确潜山岩溶区、层间岩溶区、断控岩溶区碳酸盐岩储层的空间形态与分布特征,开展了针对性的储层预测,以反演成果为主,结合属性、沉积、钻井等资料,对储层进行多属性综合预测。预测结果显示,哈拉哈塘油田塔河北区块的潜山岩溶区断裂带的通源性、连通性及扩溶性整体较好,有利于大型溶蚀孔-缝-洞储集体的形成,储层平面展布呈连片特征,储层质量最优,是未来油气勘探开发的重点区域。研究认识揭示了哈拉哈塘油田塔河北区块奥陶系断裂发育特征及断控区有利储层的分布区域,以期为有效指导深层-超深层断控区碳酸盐岩油气勘探与开发工作提供依据。

不同构造单元页岩孔隙结构差异及其油气地质意义——以四川盆地泸州地区深层页岩为例

不同构造单元页岩储层品质、含气性差异明显,构造改造作用对页岩气勘探开发具有控制作用,但关于深层页岩气的构造控制作用机理研究较少,相关认识尚不明确,制约了深层页岩气的勘探开发。为此,通过“岩心—薄片—扫描电镜”多尺度观察、全岩矿物X射线衍射分析、核磁共振等技术手段,对比分析了四川盆地南部泸州地区不同构造单元上奥陶统五峰组—下志留统龙马溪组深层页岩孔隙结构和储层特征的差异,探讨了不同构造单元页岩孔隙结构差异与储层品质的耦合关系,明确了页岩气产量差异的内在地质原因,落实了构造改造作用下的页岩气勘探开发有利区。研究结果表明:①向斜区页岩主要以有机质孔隙、非构造裂缝为主,孔径大;背斜区页岩孔隙结构被强烈改造,以矿物粒间孔、构造裂缝为主,矿物粒间孔狭长且定向排列,孔径小。②向斜区构造相对稳定,有机质孔隙、矿物粒间孔以及成岩裂缝保存较好,宏孔占比高,储集性能好,含气量和产量高;背斜区页岩储层发育大量构造裂缝与断层,孔隙和成岩裂缝被压实,孔径减小,储集性能变差,含气量和产量低。③距盆缘剥蚀区越远,构造越稳定的单元,保存条件越好,该类构造单元页岩储层越发育,含气量和产量越高,页岩气勘探开发潜力越大。结论认为,构造运动对于压力系统的影响是形成不同构造单元深层页岩孔隙结构特征差异的重要因素,并控制了页岩储层的含气性与产量;向斜区深层保存条件好,远离剥蚀区,为勘探开发的最有利区,该认识可为深层页岩气勘探开发提供技术支撑。