Research advances in non-Darcy flow in low permeability media

More and more experimental results show that Darcy’s law is not fully applicable in low permeability media,and non-Darcy flow has been identified.In this paper we reviewed the research of non-Darcy flow experiments in low-permeability media in recent decades,discuss the existence of non-Darcy flow,and summarize its constitutive equations.The reasons for the threshold gradient were also discussed and summarized for the criterion of the critical point of non-Darcy flow.On this basis,the future development of non-Darcy flow experiments in the rock and clay media were discussed,in order to provide a certain reference for subsequent research on seepage laws in low permeability media.     

塔里木盆地顺托果勒地区奥陶系鹰山组—恰尔巴克组地层划分对比研究

塔里木盆地奥陶系是重要的烃源岩和储集层,建立顺托果勒地区奥陶系鹰山组、一间房组及恰尔巴克组等时地层格架是开展地质研究和发现油气资源的基础。本文基于岩电特征,建立碳同位素对比标准,完善了奥陶系台地到斜坡相区牙形石化石带,确立顺托果勒地区奥陶系鹰山组—恰尔巴克组划分对比格架,并阐明鹰山组—恰尔巴克组特征及展布规律。研究表明,在完善牙形石化石带序列的基础上,指出鹰山组、一间房组及恰尔巴克组边界处碳同位素变化明显,地层序列发育齐全。鹰山组沉积时期是塔里木盆地台地发育的鼎盛时期,沉积环境稳定,水深基本一致,碳酸盐沉积速率虽较大但却相近。鹰山组厚度大且分布较稳定,一般在700 m左右,可细划分为4段,各段厚度为130~150 m。一间房组沉积时期,顺托果勒地区的沉积环境为一个碳酸盐缓坡环境,碳酸盐沉积速率相对较小。一间房组厚度在100~250 m不等,在顺南地区厚度最大,一般超过了200 m,最大可达250 m;古隆地区与顺北地区次之,厚度一般为130~150 m;跃进地区厚度最小,只有100 m。一间房组可细分为上下2段:上段厚度一般为60~70 m;下段为70~80 m左右。恰尔巴克组沉积时期,研究区处于一个较深水斜坡环境,沉积速率小,沉积环境稳定,全区厚度相近,而且厚度较小,一般为30~40 m。     

低渗储层裂缝发育期次研究

低渗储层中的裂缝是不同时期构造应力场的产物,具有不同的裂缝样式,确定裂缝形成期次对裂缝研究和油气聚集研究具有重要意义。岩心观察法:适用于存在明显切割关系、限制终止和组系关系的裂缝,低渗储层裂缝不发育,组系性差,这种方法通常受限。产状分析法:除分析裂缝的走向外,还需要重视倾向和倾角,并结合区域和局部构造应力场对裂缝进行期次划分。充填物分析法:需结合充填物类型、特征,以及充填物形成时的沉积、构造、油气充注特征,以达到准确划分的目的。声发射方法:可能提供裂缝发育的期次,需要结合区域声发射资料及区域构造演化史,才能准确判断裂缝的具体形成时期。综合运用上述方法,得出渤海湾盆地东营凹陷牛35块沙三中裂缝的发育期次分为4期:沙三中—沙二期、沙一—东营期、东营末期和明化镇期。     

塔河油田奥陶系生物扰动型碳酸盐岩储集层特征及其孔隙度计算样本检验模型

塔河油田奥陶系一间房组和鹰山组生物扰动型碳酸盐岩储集层非常发育。在岩芯观测的基础上,通过薄片显微镜观测与柱塞孔隙度、渗透率分析,对研究区生物扰动型碳酸盐岩储集层宏、微观特征和成因机制进行了研究,并基于岩芯资料和常规测井数据提出了一种新的孔隙度计算样本检验模型。结果表明:1）研究区奥陶系生物扰动储集层在岩芯上多呈不规则状或绸带状分布的含油斑块,潜穴充填物以白云石为主,储集空间主要是晶间孔。随着生物扰动指数的增加,平均孔隙度呈先增大后减少趋势,平均渗透率则一直增大;2）在早—中奥陶世的沉积过程中,（古）生物在碳酸盐沉积物表面或内部建造了大量形态各异的潜穴,生物扰动使得潜穴充填物和围岩基质在成分、结构上出现差异,这些差异伴随着其后的成岩过程逐步增大,这对储集层的储、渗能力具有重要影响;3）在总结前人测井孔隙度计算方法的基础上,将生物扰动指数引入密度测井孔隙度计算模型中,提出了一种基于岩芯资料和常规测井数据的孔隙度计算样本检测检验模型,并用岩芯柱塞测试结果验证了该孔隙度计算模型的有效性和准确性;该模型弥补了现有常规孔隙度模型的不足,其计算产生的拟岩芯数据可为下一步建立的通用生物扰动碳酸盐岩储集层孔隙度计算模型提供可靠的样本训练数据,也对这类储层的储量估算与油藏描述有一定的借鉴意义。     

Petrogenesis and Tectonic Implications of Middle Ordovician Ocean Island Basalts from the Chagantaolegai Ophiolitic Mélange in Junggar, NW China

Seamount accretion is one of the most significant accretionary orogenic processes in the Central Asian Orogenic Belt, but there are few paleo-seamounts reported from and debate on the tectonic evolution of the Junggar Ocean still exists. In this study, we present geochronological, mineralogical, geochemical and isotopic data for basalts from the Chagantaolegai ophiolitic mélanges in Junggar. Zircon U-Pb dating on one basalt yielded a weighted mean 206 Pb/238 U age of 469 ± 7 Ma, which suggests that it formed in the Middle Ordovician. All rock samples belong to alkaline basalt and show similar geochemical characteristics, displaying high TiO2(～3 wt%),(La/Yb)N(17.6–19.0), ΣREE(232–289 ppm) and enrichment in Nb and Ta, which implies an ocean island basalt(OIB) affinity. Based upon positive εN d(t)(+4.16 to +4.23), ΔNb(0.20–0.22) and low initial 87 Sr/86 Sr(0.70425 to 0.70452) and Zr/Nb(3.35–3.57), we suggest that the Chagantaolegai OIB samples were likely derived from a fertile mantle source related to plume. The OIB rock assemblage, chert and marble in the southern part of the Chagantaolegai ophiolitic mélange indicates that a Middle Ordovician seamount was accreted to the Boshchekul-Chingiz arc due to the northward subduction of the Junggar-Balkhash Ocean.     

唐家会煤矿透明地质保障系统构建及示范

唐家会煤矿智能化建设面临导水断层发育、带压开采等制约因素,地质条件不透明成为智能开采的技术瓶颈。唐家会煤矿以奥灰水害防治为重点,采用孔中瞬变电磁、孔间电阻率、随掘地震、随采地震、微震监测5项先进技术,构建了实时动态透明地质保障系统,实现基于透明地质模型的水害防治、快速掘进和智能回采3个目标,以支撑自主截割快速掘进和自主规划智能回采2条智能采掘作业线,其中,随采地震探测技术在61304智能回采工作面超前80 d、344 m发现了SYC1异常区并持续跟踪预报,现已得到回采揭露验证。透明地质保障系统的示范应用,取得了显著的经济效益和社会效益:① 61304工作面解放了受奥灰水威胁近100万t煤炭资源;② 61302快速掘进工作面的进尺由原来的260 m/月提高到352 m/月;③ 61304智能开采工作面日常用工减少70%。      

基于透明地质的唐家会煤矿奥灰水防治技术

唐家会煤矿6号煤开采面临导水断层多、隐伏导水构造发育,奥陶纪灰岩(简称奥灰)水害防治难度大的问题。经过不断的探索和实践,唐家会煤矿引进多种先进技术,获取大量地质、水文地质数据,构建智能地质保障系统,形成“物探钻探探查、井上下联合注浆治理、孔中瞬变电磁精细探查、注浆效果孔间电阻率检测、煤层底板微震电法联合监测”的技术思路。通过融合各类静态数据、动态数据、实时数据,完成断层、破碎带、含水层、低阻异常区等充水因素的数字建模,使地质要素、钻探物探数据可视化、透明化,以此为依托,建立一套基于透明地质的奥灰水害全时空防治体系,实现带压开采条件下奥灰水害的精细探查、靶向治理、效果检测和回采监测,取得了良好的应用效果。      

鄂尔多斯盆地中东部奥陶系碳酸盐岩-膏盐岩体系沉积特征与天然气成藏潜力

鄂尔多斯中东部地区奥陶系马家沟组发育巨厚的碳酸盐岩与膏盐岩交互的沉积体系,但对其沉积发育的规律性及其内部天然气成藏聚集的基本地质特征尚未形成明确的认识。通过对奥陶系碳酸盐岩-膏盐岩体系形成时的构造与古地理背景、沉积特征、储层发育、烃源供给及圈闭聚集等方面的分析,形成新的观点与地质认识:(1)受盐洼周边古隆起影响,奥陶系碳酸盐岩-膏盐岩共生体系形成于与外部广海周期性隔绝的局限海蒸发环境,导致其岩性“相控”与“层控”分布特征极为显著;(2)首次提出“非层状沉积分异”的概念,并认为它是控制奥陶系内幕“溶孔型”储层发育的决定性因素;(3)受区域岩性相变及后期构造反转的控制,奥陶系盐下层系具有形成大区域分布的岩性圈闭体系的有利条件;(4)盐下层系虽自身的海相烃源岩生烃潜力有限,但由于燕山期东部构造抬升与西侧上古生界煤系烃源“供烃窗口”及膏盐封盖层区域性连续分布等要素密切配合,仍具有规模供烃、大区带成藏的潜力。     

鄂尔多斯盆地西缘奥陶系拉什仲组复合水道沉积特征及演化

鄂尔多斯盆地西缘奥陶系拉什仲组发育一套砂泥互层的深水重力流沉积,其下部重力流复合水道发育。综合野外实测、薄片和粒度分析等,探讨复合水道沉积特征、形成过程及主控因素,最终建立其沉积模式。结果表明：(1)研究区发育5种岩相和3种岩相组合,即块状层理砾屑灰岩相(Cm)、粒序层理细—粉砂岩相(Sg)、平行层理砂岩相(Sp)、交错层理粉砂岩相(Sc)、水平层理(泥)页岩相(Sh),分别代表碎屑流沉积(Cm)、浊流沉积(Sg, Sp, Sc)及深水原地沉积(Sh);(2)根据复合水道内部单一水道形态、岩相组合及粒度等将复合水道分为4个期次,反映重力流能量由强到弱的变化过程;(3)复合水道多期次发育与相对海平面升降、沉积物供给、构造运动和重力流规模及能量变化密切相关;(4)重力流沉积为斜坡—盆地环境中复合水道沉积模式。该研究可补充对研究区重力流水道认识,为油气勘探提供借鉴。     

Roller-coaster atmospheric-terrestrial-oceanic-climatic system during Ordovician-Silurian transition: Consequences of large igneous provinces

The Ordovician-Silurian transition (OST) hosted profound and frequent changes in the atmospheric-terrestrial-oceanic-climatic system (ATOCS). Previous studies have found contrasting stages for such changes, primarily based on hiatus-interrupted sections. However, the dominant driving factors and mechanisms reconciling such frequent changes remain controversial. Mercury isotopes, which undergo both mass-dependent and mass-independent fractionation, can provide critical insights into the deep-time ATOCSs, especially for those impacted by large igneous provinces (LIPs) events. Here, we build a high-resolution multi-proxy record of Hg (concentrations and isotopic compositions) combined with organic carbon isotopes (δ¹³C_org) and whole-rock geochemical data (including trace elements and phosphorus) from continuous cores in the Yangtze Platform, South China. Our data, combined with reported ones, indicate the occurrence of LIP eruptions against localized volcanism, and four successive, yet contrasting stages of ATOCSs during the OST. Moreover, we identified the coupling between two-pulse LIP magmatism and extreme ATOCSs, each with special pCO₂, weathering rate, primary productivity, redox condition, climatic mode, and biotic evolution. For stage I, the first pulse of LIP magmatism triggered global warming, enhanced terrestrial weathering, oceanic acidification, eutrophication, anoxia, P recycling, and thereby widespread deposition of black shales. During stage II, the Hirnantian glaciation and oxygenation arose from the intense chemical weathering and black shale deposition of stage I; slashed terrestrial weathering and oceanic oxygenation facilitated CO₂ accumulation. In stage III, another pulse of LIP magmatism triggered the de-glaciation, and the ATOCS was largely similar to that of stage I. This led to another round of oxygenation and positive δ¹³C_org excursion in stage IV. Compared with the environmental pressure by the peculiar ATOCS of each stage, their transitions might have been more devastating in triggering the prolonged Late Ordovician Mass Extinction (LOME). Moreover, limited biotic recovery was possible in the later portion of stages I and III. The multi-proxy study of continuous strata of the OST provides an excellent framework for better illuminating LIPs’ essential role in driving the “roller-coaster” behavior of the ATOCS and thus biotic crisis during the pivotal period of the OST.