昭通示范区黄金坝气田五峰—龙马溪组页岩气储层地质特征

昭通国家级页岩气示范区黄金坝气田是继礁石坝和长宁—威远之后中国又一个在页岩气勘探、开发领域实现重大突破的地区,为了系统地展示黄金坝气田页岩气资源富集的储层条件,为未来的勘探工作提供参考,以五峰—龙马溪组页岩气储层为研究对象,从区域地质条件、储层岩石学、物性和地球化学4个方面对该页岩气储层进行了综合研究。结果表明稳定的区域构造和良好的顶底板条件是黄金坝地区页岩气资源富集的关键,良好的保存条件使储层维持了较高的压力(压力系数1);较高的孔隙度(平均4%)和TOC含量(目的层2%)提供了良好的储集空间,使储层具有较高的含气量(1.35~3.48 cm3/g,平均2.50 cm3/g);天然气地球化学数据表明,区内天然气主要成分为CH4(97%),其次还含有少量的C2H6、C3H8和CO2;天然气同位素数据表明烃类C同位素组成发生了倒转,表明储层具有良好的封闭性。但储层孔隙系统较为复杂,且非均质性极强,从而导致渗透率较低,在储层改造施工过程中应予以充分考虑。总体上,黄金坝气田具有较好的开发前景,生产测试表明,区内直井压裂产量为0.5×104~3.5×104m3/d/井,水平井压裂产量可达12×104~40×104m3/d/井。     

济阳坳陷古近系泥页岩成因相划分

系统岩心观察和高密度薄片鉴定等分析测试资料研究结果显示,济阳坳陷沙三下-沙四上泥页岩成分组成及构造类型主要受沉积作用控制,岩石结构特征主要受成岩作用控制。根据泥页岩中方解石成因及重结晶程度,结合岩石成分及构造特征,将济阳坳陷沙三下-沙四上泥页岩划分为沉积主控型、沉积-成岩双控型及成岩主控型三大成因相。沉积主控型分布最为广泛,岩相类型多样,构造特征反映成因环境;沉积-成岩双控型主要见于纹层状岩相,由泥质纹层与显晶粒状方解石纹层互层构成;成岩主控型以柱状、柱纤状方解石垂直层面呈脉状、透镜状产出为特征。成岩主控型和沉积-成岩双控型泥页岩与页岩油气关系密切,是重要的有利成因相类型。     

油气上窜速度实用计算方法

油气上窜速度对钻井施工中下一步施工方案的制定具有重要参考价值。文章在总结分析前人经验的基础上结合现场施工实际对传统油气上窜速度计算公式加以修正,并对修正后的公式中涉及到的参数进行了逐一分析,在不影响正常施工工序的条件下使公式中各参数取值准确性进一步提高。通过现场工程测试,该方法简单实用且计算准确性较高。该计算方法在保证计算结果准确性的同时,也具备较强的现场可操作性,通过大量的实践检验后可进一步推广。     

涪陵页岩气水平井定向技术

涪陵页岩气产能示范区作为国内首个国家级页岩气示范区,自2012年启动以来,通过不断的技术攻关和技术创新,形成了完善的国产化水平井钻井技术系列。2015年随着区块的转移,地质条件更趋复杂,定向施工面临着更多新的技术难题,在已有成熟技术的基础上,通过技术优化和先进的降摩减扭工具的应用,有效地解决了新区块的施工难题,推进了页岩气产能区的建设。     

Formation of low permeability reservoirs and gas accumulation process in the Daniudi Gas Field,Northeast Ordos Basin,China

The Daniudi Gas Field is a typical large-scale coal-generated wet gas field located in the northeastern Ordos Basin that contains multiple Upper Paleozoic gas-bearing layers and considerable reserves of gas. Based on integrated analysis of reservoir petrology, carbonate cement C–O isotope, geochemistry of source rocks and HC gas and numerical basin modeling, a comprehensive study focusing on the formation of low permeability reservoirs and gas generation process uncovers a different gas accumulation scene in Daniudi Gas Field. The gas accumulation discovered was controlled by the reservoir permeability reduction and gas generation process, and can be divided into two distinct stages by the low permeability reservoir formation time: before the low permeability reservoir formation, the less matured gas was driven by buoyancy, migrated laterally towards NE and then accumulated in NE favorable traps during Late Triassic to early Early Cretaceous; after the low permeability reservoir formation, highly matured gas was driven by excessive pressure, migrated vertically and accumulated in-situ or near the gas-generating centers during early to late Early Cretaceous. The coupling relationship between reservoir diagenetic evolution and gas generation process controlled on gas accumulation of the Daniudi Gas Field. This study will aid in understanding the gas accumulation process and planning further E&D of the Upper Paleozoic super-imposed gas layers in the whole Ordos Basin and other similar super-imposed low permeability gas layer basins.     

The diagenetic history of Oligocene-Miocene sandstones of the Austrian north Alpine foreland basin

Diagenesis is an essential tool to reconstruct the development of reservoir rocks. Diagenetic processes - precipitation and dissolution - have an influence on pore space. The present paper aims to study the diagenetic history of deep-marine sandstones of the Austrian Alpine Foreland Basin. To reach that goal, sediment petrology and diagenetic features of more than 110 sandstone samples from water- and gas-bearing sections from gas fields within the Oligocene-Miocene Puchkirchen Group and Hall Formation has been investigated. Special emphasis was put on samples in the vicinity of the gas-water contact (GWC). The sediment petrography of sandstones of Puchkirchen Group and Hall Formation is similar; hence their diagenesis proceeded the same way. In fact, primary mineralogy was controlled by paleo-geography with increasing transport distance and diverse detrital input.Sediment petrographically, investigated sandstones from the water-bearing horizon seemed quite comparable to the gas-bearing sediments. In general, they can be classified as feldspatic litharenites to litharenites and display porosities of up to 30% and permeabilities of up to 1300 mD. The carbon and oxygen isotopic composition of bulk carbonate cements from these sandstones range from−3.8 to +2.2 and from −7.5 to +0.2‰ [VPDB]. However, near the Gas-Water Contact (GWC) a horizon with low porosities (<3%) and permeabilities (<0.1 mD) is present. This zone is completely cemented with calcite, which has a blocky/homogenous morphology. A slight, but significant negative shift in δ18O isotopy (−2.5‰) is evident.During early diagenesis the first carbonate generations formed. First a fibrous calcite and afterwards a micritic calcite precipitated. Further siliciclastic minerals, such as quartz and feldspar (K-feldspar and minor plagioclase), exhibit corroded grains. Occasionally, clay minerals (illite; smectite, chlorite) formed as rims around detrital grains. Late diagenesis is indicated by the formation of a low permeable zone at the GWC.     

山东济宁许厂煤矿下组煤瓦斯与二氧化碳开发利用前景及存在的问题

许厂煤矿下组煤中蕴藏着较为丰富的瓦斯、二氧化碳资源。下组煤位于瓦斯风化带内,含瓦斯、二氧化碳和氮气等气体,瓦斯含量与埋藏深度呈正相关关系,主要存在低含量瓦斯、二氧化碳抽采率、二氧化碳资源化转换等技术方面的问题。从国家相关优惠政策、资源优势、煤与煤层气一体化开发技术、近水平长钻孔定向钻进技术、煤层压裂造缝技术、煤层注气增产技术和瓦斯、二氧化碳气体提纯技术等关键技术的发展程度,结合煤矿的下组煤层的开采方案,认为许厂煤矿有着较好的煤炭与瓦斯、二氧化碳一体化开发利用前景。     

频谱分解技术在泥页岩储层含气性预测中的应用——以柴达木盆地鱼卡凹陷为例

针对柴达木盆地北缘鱼卡凹陷中侏罗统大煤沟组泥页岩,利用地震频谱曲线在不同流体介质储层中的形态、斜率、主频与中心频率的差值等属性参数特征,识别陆相泥页岩层系的地震频谱属性特征,预测含气性。研究结果表明,中侏罗统大煤沟组上部能量系数较低,平均为0.6719,下部能量系数较高,平均为0.7521,结合现场含气量和全烃特征认为,可以以能量系数0.7为界线,作为识别下部和上部含气性的标志,下部明显比上部含气性好。平面上进一步圈定了2个有利目标区,得到柴页1井勘探验证。因此,频谱分解技术可应用于中国陆相页岩气的勘查开发。     

柴达木盆地北缘富氦天然气的发现——兼议成藏地质条件

在柴达木盆地北缘全吉山、团鱼山地区的煤炭钻孔和泥页岩解吸气中发现了体积分数较高的氦气显示。对2个地区的6件样品进行甲烷C同位素和He同位素分析,其中2个样品的δ13C1值分别为-38.4‰和-39.9‰,属于有机成因。4个样品的3He/4He同位素测试结果在0.03×10-6~1.3×10-6之间,表明氦气来源以壳源氦为主,个别样品有少量幔源氦加入。通过区域背景资料和物探资料分析认为,柴北缘壳源成因的氦可能主要来源于基底富U、Th花岗岩体的放射性衰变,而柴北缘的山前深大断裂则可为氦的运移提供良好通道。氦气产生后,在垂向运移过程中结合其他烃类或非烃类气体,在侏罗系、古近系—新近系良好的储盖条件下,有可能形成独特的富氦天然气富集。     

柴达木盆地北缘侏罗系页岩气地质条件

侏罗系泥页岩是柴达木盆地的主力烃源岩之一,具备形成页岩油气的地质条件。对采自柴北缘鱼卡、大煤沟、小煤沟、开源、绿草沟、大头羊等煤矿附近地表露头的11块中侏罗统泥页岩样品进行单样品多参数实验分析,探讨了陆相页岩有机地化、储层物性、含气量等参数之间的关系,建立了页岩气资源评价参数体系。结果表明,柴达木盆地北缘中侏罗世处于浅湖-半深湖湖相沉积,断裂较发育,泥页岩富含有机质,具有低孔、低渗、低熟、较高含气量等特点,具备形成页岩油气的地质条件,进一步的勘查开发需优选地层压力系数高、保存条件较好、脆性矿物含量高的页岩气甜点区。