南祁连盆地碳酸盐岩储层特征与评价

通过岩石薄片、扫描电镜和物性等资料的综合分析,对南祁连盆地碳酸盐岩储层特征进行了研究。 结果表明：储层岩石类型主要为鲕粒灰岩、生物碎屑灰岩、微晶灰岩和少量的白云岩,其中最佳储集体鲕 粒灰岩主要发育于中三叠统大加连组;储集空间以次生孔隙为主,主要发育粒内溶孔、粒间溶孔、晶间溶 孔及裂缝;储层物性差,为特低孔、低渗储层。研究认为,白云石化作用、溶蚀作用和构造作用对储层孔、渗 性具有改善作用,胶结作用和压实作用对储层孔、渗性具有破坏作用,导致储层孔、渗能力变差。根据储层 物性特征和孔隙结构参数将研究区储层划分为Ⅲ 类和Ⅳ 类储层。     

羌塘盆地侏罗系碳酸盐岩储集层特征

在野外露头资料研究的基础上,运用岩石薄片、铸体薄片、扫描电镜、常规物性、毛细管压力曲线等手段,对羌塘盆地侏罗系碳酸盐岩储集层的岩石学、孔渗性及孔隙结构等特征作了详细研究。岩石类型主要为颗粒灰岩,包括内碎屑灰岩、鲕粒灰岩和生屑灰岩。储集空间包括孔隙和裂缝两种,孔隙主要为次生溶孔,裂缝为构造缝和溶蚀缝。孔隙的微观结构较差,基本上属于低孔低渗致密储集层。强烈的机械压实作用、胶结作用是导致储集层孔隙结构变差的主要因素,后期的溶解作用对储集层物性有一定的改善。构造作用使得岩石中裂隙发育,提高了岩石孔渗性,极大地改善了岩石的储集性能。     

吉木萨尔凹陷芦草沟组储层特征及主控因素

为研究吉木萨尔凹陷芦草沟组页岩油储层特征及主控因素,开展岩心观察、铸体薄片鉴定、扫描电镜分析及全岩分析等工作,研究其岩石学特征、物性特征和成岩作用等。结果表明:芦草沟组岩石类型主要为碎屑岩、碳酸盐岩和混合细粒岩等,成分成熟度和结构成熟度均较低,分选性中等,原生粒间孔和次生溶孔是主要储集空间,砂岩孔隙度平均为7.34%,渗透率平均为0.079 mD,属低渗致密储层;储层发育主要受沉积和成岩双重作用控制,其中沉积作用控制着储层岩石类型的发育和分布,成岩作用过程中压实作用和胶结作用是导致储层孔隙度下降的主要原因,溶蚀作用对储层物性条件起到一定的改善作用。芦草沟组储层共经历了3次致密化阶段,压实作用是早期致密的主要原因,持续压实作用和硅质胶结作用在中期致密化阶段起到主导作用,晚期压实作用和碳酸盐岩、黏土矿物胶结共同作用于储层,使储层进一步致密化。该成果可为开发吉木萨尔凹陷芦草沟组页岩油提供一定理论依据。     

川东南地区飞仙关组碳酸盐岩储层特征

在野外剖面、钻井岩心详细观察的基础上,通过对染色薄片、岩石薄片、扫描电镜和物性等资料的综合分析,对川东南地区下三叠统飞仙关组碳酸盐岩储层特征的研究结果表明,储集层岩石类型主要为鲕粒灰岩、泥晶灰岩和少量的白云岩,其中最佳储集体鲕粒灰岩主要发育于飞仙关组三段;储集层储集空间以次生孔隙为主,主要发育晶间孔、晶间溶孔、粒间溶孔和粒内溶孔4种类型;储集层物性较差,为低孔隙度、低渗透率的储集层。研究认为沉积相、成岩作用和构造运动对储集层具有明显的影响,其中沉积相类型控制了储集层发育位置,而成岩作用和构造运动则对储集层物性具有控制性的影响。白云石化作用和压溶作用较好的改善了储层的孔渗情况,胶结作用和压实作用则对储层孔渗起到破坏性作用,导致了储层的孔渗能力变差;构造运动则总体上体现为改良研究区飞仙关组储层的孔渗能力。     

DIAGENESIS OF TIGHT‐GAS SANDSTONES IN THE LOWER CRETACEOUS DENGLOUKU FORMATION,SONGLIAO BASIN,NE CHINA: IMPLICATIONS FOR RESERVOIR QUALITY

Non‐marine tight‐gas sandstones have not been studied intensively in terms of diagenesis and reservoir‐quality evaluation. This paper investigates the sandstones in the Lower Cretaceous Denglouku Formation in the Songliao Basin, NE China, which comprise a tight reservoir for natural gas. Core samples of the sandstones were obtained from eight wells located in two gasfields and were described in terms of lithology and sedimentology with the aid of wireline log interpretation; other data included thin section petrography, and X‐ray diffraction analyses and scanning electron microscopy. The sandstones mainly comprise moderate‐ to well‐sorted, fine‐ to medium‐grained feldspathic litharenites deposited in braided fluvial to braid‐delta settings under warm, arid to semi‐arid climatic conditions. Diagenetic processes which have affected the sandstones include compaction and cementation by calcite, dolomite, ferroan calcite, quartz, chlorite and illite. Porosity characteristics of the sandstones are closely linked to depositional facies, and the sandstones can be divided on the basis of sediment textures and depositional facies into three groups which have distinctive diagenetic features. The best reservoirs are represented by relatively coarse‐grained sandstones deposited in braid‐delta mouth bars and distributary channels and braided fluvial channels; these sandstones have relatively high porosity (up to 5%) and contain large amounts of chlorite and illite pore‐lining cements but relatively minor carbonate cement. A reservoir quality prediction model is proposed and incorporates textural, depositional and diagenetic attributes. The model will help to identify sweet spots in non‐marine tight‐gas sandstones elsewhere, and will contribute to more effective field development.     

柴达木盆地油砂山油田下油砂山组砂岩成岩作用和孔隙结构

对青海柴达木盆地油砂山油田下油砂山组砂、泥岩样品的分析测试表明，下油砂山组湖相三角洲砂岩的成分成熟度和结构成熟度均较低，成岩作用已达到中成岩阶段的成熟Ａ期或Ｂ期；早成岩阶段的主要成岩作用是碳酸盐胶结作用以及压实作用引起的颗粒重排；中成岩阶段未成熟期则以机械实作用为主，半成熟期以方解石和方沸石胶结作用为主，成熟Ａ期或Ｂ期的主要成岩事件是烃类大量成熟引起的晚期溶蚀。该三角洲体系中河道砂体、河口坝砂体和     

POROSITY DESTRUCTION IN CARBONATE PLATFORMS

The important thing to understand about carbonate diagenesis is not how porosity is created, but how it is destroyed. Detailed core observations from two deeply‐buried carbonate platform successions (the Finnmark platform, offshore north Norway; and the Khuff Formation, offshore Iran) show that in both cases most vertical porosity variation can be accounted for by only two or three factors, namely: (1) stylolite frequency, (2) proportion of argillaceous beds, and (3) anhydrite cement. The spatial distribution of these factors is determined by the depositional distribution of clay minerals (important for localizing chemical compaction) and the occurrence of hypersaline depositional conditions and associated brine reflux (important for localizing anhydrite precipitation and dolomitisation). However, the intensity of chemical compaction and consequent porosity loss in adjacent beds by carbonate cementation also depend upon thermal exposure (temperature as a function of time). Evidence from the Finnmark platform and other examples indicate that the stratigraphic distribution of early‐formed dolomite is also important for porosity preservation during burial, but this factor is not apparent in the Khuff dataset. Insofar as the Finnmark and Khuff platforms can be regarded as representative of carbonate reservoirs in general, recognition of the above porosity‐controlling factors may provide the basis for general models predicting carbonate reservoir potential both locally (reservoir‐model scale) and regionally (exploration‐scale). Distributions of clay, anhydrite, and dolomitization should be predictable from stratigraphic architecture, whereas variations in thermal exposure can be mapped from basin analysis. In the present examples at least, factors that do not need to be considered include eogenetic carbonate cementation and dissolution, depositional facies (other than aspects related to clay and anhydrite content), and mesogenetic leaching to create late secondary porosity.     

IMPACT OF DIAGENESIS ON RESERVOIR QUALITY IN RAMP CARBONATES: GIALO FORMATION (MIDDLE EOCENE), SIRT BASIN,LIBYA

The reservoir quality of Middle Eocene carbonates in the intracratonic Sirt Basin is strongly influenced by depositional facies and various diagenetic processes. Based on data from core samples and well logs from five boreholes in the Assumood and Sahl gasfields in the subsurface of the north‐central Sirt Basin, six major carbonate facies (and fourteen microfacies) are distinguished in the Middle Eocene Gialo Formation (thickness ～1100 ft/335 m). Wackestones‐packstones dominate the Gialo Formation with abundant grains of larger benthic foraminifera, especially nummulites, in a matrix composed mostly of finely comminuted bioclastic material. Sediments were deposited as a mosaic of facies on a broad carbonate ramp in moderate‐energy nummulite‐packstone banks, with locally restricted back‐bank lagoons and fore‐bank areas of foraminiferal debris passing to offshore lime mudstones. Marine diagenesis was minor with micritization of bioclasts and rare vadose marine fibrous cements. Sparry calcite cements are ubiquitous and were precipitated during shallow to moderate burial from seawater and/or meteoric water, the latter largely unaffected by surface‐pedogenic processes. This is indicated by the fabrics and pre‐ and post‐compaction precipitation of drusy spar and echinoderm overgrowths, and supported by their bright‐to‐dull luminescence and low negative δ¹⁸O signatures (‐2.68 to ‐4.16%° PDB). Some early neomorphic alteration of calcitic bioclasts is suggested by bright CL and marine to low negative δ¹⁸O values (‐1.06 to –3.93%° PDB). Bioclastic grains have δ¹³C values ranging between 0.76 and 1.19%° PDB, interpreted as marine signatures. Similar low positive δ¹³C values of the cements (0.9 to 1.05 %°) indicate a source of carbonate from dissolution of grains and/or seawater/meteoric water, but without any near‐surface/soil effects. Dissolution of grains and matrix, notably originally aragonitic grains but also the originally high‐Mg calcite nummulites, was a major porosity‐enhancing process, and took place from shallow to moderate burial depths. Fractures may locally have increased porosity too. Shallow‐water packstones/rudstones containing both primary intergranular and secondary biomouldic porosity have the best reservoir quality and these are concentrated in the upper parts (top ～100 ft/30 m) of the wells, with porosity‐permeability decreasing downwards. This trend relates to the broad, large‐scale facies pattern of more mud‐dominated facies giving way upwards to more grainy, nummulite‐dominated facies as a result of an overall shallowing of the depositional environment. In addition, the influx of meteoric waters in the upper part of the Gialo platform, before drowning and deposition of the overlying Augila Shale, increased porosity through dissolution. This integrated study has helped in understanding the reservoir heterogeneity and hydrocarbon potential of the Gialo carbonates.     

胶结作用在深埋藏砂岩孔隙保存中的意义

在储层演化中 ,砂岩中很多胶结作用都是重要的保持性成岩作用 ,是深埋藏条件下砂岩孔 隙得以保持的重要机制。该文根据东海盆地古近系、 鄂尔多斯盆地上古生界和三叠系以及四川盆 地三叠系砂岩储层中(铁)白云石胶结物、 硅质胶结物和粘土矿物胶结物的产状、 胶结作用发生时间 和机制的研究 ,提出这些胶结作用很大一部分都发生在早成岩阶段有效压实作用发生之前 ,它们或 与埋藏早期的构造抬升有关 ,或与煤系地层早期酸性流体有关。这种分散的早期胶结作用可以提 高岩石机械强度 ,增加岩石的抗压实能力 ,改变以后浅埋藏 -深埋藏过程中岩石的孔隙度2深度曲 线 ,最终使砂岩孔隙在深埋藏条件下得以保存 ,这在储层质量预测中具有重要意义。     

黔西北毕节地区中二叠统碳酸盐岩成岩作用

黔西北毕节地区中二叠统栖霞组和茅口组碳酸盐岩发育,地层出露良好。通过野外剖面的观察和实测,室内铸体薄片的鉴定、阴极发光分析以及碳氧同位素分析,结合区域地质背景和前人研究成果,认为黔西北毕节地区中二叠统碳酸盐岩的成岩作用具有如下特征：①中二叠统主要发育颗粒结构的灰岩和白云质灰岩（豹斑灰岩）,岩石样品整体显示不发光—弱发光的阴极发光特征,碳同位素比值为1.2‰~4.6‰,表明岩石未受大气淡水的显著影响;②中二叠统碳酸盐岩受成岩改造作用强烈,发育海水潜流环境的泥晶化作用、海水渗流环境的等厚环边和马牙状方解石胶结作用、淡水渗流和潜流环境的等轴粒状—块状胶结和方解石的共轴生长、以及硅化作用、白云化作用和白云石的溶解作用、破裂作用、压实压溶作用等成岩作用,据此建立了相应的成岩演化序列;③硅化作用和白云化作用可能受到局部特殊热事件的影响,但具体的影响程度需要进一步的研究。     

MICROPOROSITY IN THE UPPER JURASSIC ARAB‐D CARBONATE RESERVOIR,CENTRAL SAUDI ARABIA: AN OUTCROP ANALOGUE STUDY

This study investigates microporosity in an outcrop analogue of the Upper Jurassic (Kimmeridgian) Arab‐D carbonate reservoir in central Saudi Arabia, integrating outcrop facies analysis, petrographic and SEM data and statistical analyses. At the study location in Wadi Nisah, the outcropping succession includes the uppermost Jubaila Formation and the entire Arab‐D Member of the Arab Formation which together comprise the Arab‐D reservoir interval. The succession is composed of eight lithofacies which can be grouped into three lithofacies associations based on their depositional environments. The stromatoporoid lithofacies association includes dolomitic mudstones, dolomitic wackestones and stromatoporoid wackestones and packstones; the skeletal bank lithofacies association includes burrowed fossiliferous wackestones and peloidal fossiliferous grainstones; and the tidal flat lithofacies association comprises laminated mudstones, wave‐rippled sandy grainstones, and supra‐ and intertidal muds with rip‐up clasts. The lithofacies were classified into mud‐dominated, grain‐dominated and dolostone textural groups. Microporosity and associated permeability in the analysed samples (n = 125 for porosity and n = 61 for permeability) range from 0.11% to 4.8 % and 0.36 to 4.35 mD, respectively. Three types of microporosity were observed: (i) between macro‐ and micro‐sparry calcite crystals; (ii) between micrites of varying morphologies; and (iii) within macro‐sized dolomite crystals. Microporosity distribution was controlled by sparry calcite cement, micrite crystal size, sorting and shape, and the presence of dolomite crystals. Statistical analyses of microporosity and associated permeability show non‐normal distributions for both variables. Coefficients of variation indicated high variability for porosity and permeability, which may be attributed to the high degree of heterogeneity in the pore system. In general there was a poor correlation between microporosity and permeability, but the correlation improved when visualized for individual textural groups.     

川西—川西北地区上三叠统碎屑储集岩成岩作用

川西—川西北地区上三叠统包括须家河组和香溪群;主要沉积相类型有河流三角洲、海湾、湖泊和冲积扇.上三叠统储集岩主要由长石岩屑砂岩、岩屑长石砂岩、岩屑砂岩、长石石英砂岩、岩屑石英砂岩及少量长石砂岩组成.岩石碎屑颗粒含量81%~95%,碎屑中有较多长石和岩屑,具低的成分成熟度和高的结构成熟度.原始孔隙度的45.0%~77.5%是由于压实作用而丧失的.胶结作用对储层的破坏性仅次于压实作用,包括自生石英、长石、粘土矿物和碳酸盐矿物的沉淀.石英加大的深度可能大于1 800~4 080 m.受有机质影响,碳酸盐胶结物具较低的δ13C值(PDB),为-4.85‰~2.91‰;由于淡水淋滤和深埋藏,有较低的δ18O值(PDB),为-16.97‰~-7.86‰.溶蚀作用是对储集岩最重要的建设性作用,以长石溶蚀最为常见.粘土矿物以伊利石为主,无蒙皂石.镜质体反射率为0.81%~2.48%,推测古地温大部分在85~160℃.储集岩成岩作用已进入到晚成岩作用阶段的中期.裂缝在很大程度上改善了储集性能.由于压实作用和胶结作用影响大,溶蚀作用影响小,储集岩以低孔、低渗为特征.      

三塘湖盆地牛圈湖油田低孔特低渗储集层特征及形成机理

三塘湖盆地牛圈湖油田西山窑组储集层埋深浅（小于2 000 m），储集层类型却属于低孔特低渗型。为揭示其储集层特征及形成机理，通过岩心观察、铸体薄片鉴定、常规高压压汞实验和电镜扫描等技术，结合区域构造资料分析，进行了储集层特征及低孔特低渗形成机理研究。结果表明:西山窑组储集层以长石岩屑砂岩为主，储集空间类型有原生粒间孔、溶蚀孔及裂缝。沉积、成岩和构造三重因素共同作用，造成了储集层低孔特低渗；西山窑组早期因为含煤地层的酸性环境导致碳酸盐胶结弱，颗粒间缺少支撑而发生较强烈的快速压实，同时沉积作用又从粒径大小和填隙物含量上控制着储集层原始物性特征，成岩过程中发生的压实作用致使减孔率达到18%，酸性环境还导致高岭石的大量形成、石英次生加大边的发育及晚期的含铁质碳酸盐胶结的发育，胶结减孔率为5%左右；构造应力形成的裂缝为后期溶蚀作用的发生提供了一定通道，但岩石已在早期压实作用下基本固结致密，且煤层厚度较薄、酸性流体含量不足，难以在小体积粒间大规模流动，溶解强度不大，导致对渗透率贡献很大的粗喉道较少，形成了低孔特低渗储集层。      

生烃伴生酸性流体对碳酸盐岩储层改造效应的模拟实验

深层-超深层碳酸盐岩是目前油气勘探聚焦的重点领域,其储层的形成和保持机制是制约深层储层预测的关键科学问题。为了明确埋藏溶蚀作用下酸性流体对碳酸盐岩储层物性的影响,有必要开展烃源岩地层孔隙生烃模拟和溶蚀模拟实验（简称生烃及溶蚀模拟实验）,定性定量厘清中、深层埋藏环境下烃源岩与碳酸盐岩储层演化过程。采用自主研发设计的生烃模拟实验装置和溶蚀模拟实验装置,以塔里木盆地奥陶系鹰山组灰岩和云南禄劝低成熟烃源岩为实验对象,利用岩相学和地球化学相结合的分析手段,查明中、深埋藏环境下生烃热演化过程中伴生的复杂酸性流体改造碳酸盐岩储层的过程及其控制因素,探索烃源岩生烃过程对碳酸盐岩围岩的改造规律。实验表明：中、深层埋藏环境下烃源岩热演化过程中伴生的有机酸和CO₂等酸性流体对碳酸盐岩储层产生明显溶蚀作用,扩大原有储集空间并提高孔隙度,并且随着埋藏深度增加,溶蚀作用明显减弱;流体在运移过程中是否能够改善储层物性,由流体中的碳酸钙饱和度、流体流速、水岩比以及原始孔隙结构等因素共同决定。此研究能够为深层-超深层碳酸盐岩优质储层的预测提供一定的理论基础。     

早期碳酸盐胶结作用对恩平凹陷珠江组砂岩孔隙演化模式的影响

珠江口盆地恩平凹陷的碎屑岩储层中存在早期碳酸盐胶结,为分析胶结作用对储层孔隙演化的影响,以便为储层预测提供依据,采用普通薄片、铸体薄片、扫描电镜、压汞等分析方法,结合岩石物性研究和测井解释结果,分析了该区古近纪珠江组早期碳酸盐胶结砂岩的孔喉特征,发现基底式胶结的钙质砂岩,表现为“悬浮砂”结构,主要为低孔隙度、低渗透率储层;而孔隙式胶结的钙质砂岩,其渗透率一般超过100 mD,平均孔喉半径大于15 μm,为高孔隙度、高渗透率储层。在分析珠江组主要成岩作用类型的基础上,探讨了早期碳酸盐胶结作用对储层孔隙演化模式的影响,发现由于碳酸盐含量的不同,其影响具有双重性：①基底式胶结的钙质砂岩一般坚硬致密,难以被溶蚀改造,孔喉不发育;②孔隙式胶结利于原生孔隙保存和次生孔隙形成,其胶结的钙质砂岩在后期酸性流体溶蚀作用下可以产生特大溶孔,形成高孔、高渗储层。结论认为：该区早期碳酸盐胶结的海相砂岩,抗压实能力较强,在酸性流体作用下具备形成优质储层的潜能。     

渤海湾盆地济阳坳陷沾车地区沙四上亚段湖相碳酸盐岩储层特征

渤海湾盆地济阳坳陷沾车地区沙四上亚段湖相碳酸盐岩环绕义和庄凸起大面积分布,发育了众多油藏,也拥有较多的钻井资料。沾车地区湖相碳酸盐岩储层岩石类型分为石灰岩、白云岩、混积岩3类,石灰岩又划分为内碎屑灰岩、生物碎屑灰岩、复合颗粒灰岩和泥晶灰岩等类型,白云岩主要为结晶白云岩,划分为藻屑白云岩、藻格架白云岩等,混积岩则为碳酸盐岩与碎屑岩的混合沉积;储层孔隙类型有原生孔隙、次生孔隙和裂缝3种;储层整体上具有低孔-低渗的特点,储层物性与岩石类型有很大关系;沉积环境是储层好坏的主控因素,压实、胶结和溶蚀等成岩作用对储层的改造起到了一定影响。储层主要受控于沉积古地理环境,义和庄凸起南部、东部的陡坡带储层发育最好;陈家庄凸起北部及义和庄凸起北部的缓坡带储层相对发育,礁、滩之间或者湖湾和半深水地区为差储层、非储层发育相带。      

塔里木盆地古生代海相碳酸盐岩储集岩特征

通过对塔里木盆地古生代碳酸盐岩储集岩的勘探和研究,较系统地阐述了储集岩类型、储集空间类型、储集性能以及碳酸盐岩成岩作用等,并进行了评价。塔里木盆地古生代碳酸盐岩储集岩类型主要有古岩溶风化壳型、礁滩型、鲕粒滩型及白云岩型4类。5期构造运动形成了5期古岩溶储集体,即下寒武统—上震旦统、中奥陶统—上奥陶统、志留系—奥陶系、石炭系与下伏地层、三叠系—前三叠系之间的古岩溶。碳酸盐岩储集空间类型主要分为孔隙—孔洞和裂缝2大类型。孔隙-孔洞包括微孔隙、晶间孔隙、溶蚀孔隙和溶蚀孔洞;裂缝主要有成岩裂缝、与区域构造有关的裂缝、与褶皱有关的裂缝、与断裂有关的裂缝、与深部地层负荷和孔隙压力有关的裂缝等。碳酸盐岩储层主要成岩作用有压实、压溶、胶结、白云化、重结晶、硅化和溶蚀等。储集岩主要有白云岩和灰岩2大类,白云岩以裂缝-孔洞型为主,而灰岩主要为裂缝型,仅有少量孔洞-裂缝型及裂缝-溶洞型,因此白云岩储层的储集性能明显好于灰岩。      

FACIES HETEROGENEITIES AND 3D POROSITY MODELLING IN AN OLIGOCENE (UPPER CHATTIAN) CARBONATE RAMP,SALENTO PENINSULA,SOUTHERN ITALY

Appraisal of the volumes of fluid in a carbonate reservoir will typically require a reliable predictive model. This can be achieved by combining studies of well-exposed carbonate successions with 3D models in order to obtain reliable quantitative data. In this paper, we present a detailed outcrop study and a 3D porosity model of a well-exposed Oligocene carbonate ramp (Salento Peninsula, southern Italy) to investigate the nature of small-scale facies and porosity heterogeneities. Porosity and permeability in the ramp carbonates appear to be controlled by the original mineralogy of skeletal components and by depositional textures. The aims of the study were therefore to identify the factors controlling porosity development in an undeformed carbonate ramp; to model the scale-dependent heterogeneities characteristic of the facies associations; and finally to produce a 3D model of the porosity distribution. The upper Chattian Porto Badisco Calcarenite which crops out along the coast of the Salento Peninsula consists of six lithofacies ranging from inner ramp deposits to fine-grained outer ramp calcarenites. The lithofacies are: inner ramp small benthic foraminiferal wackestone-packstones associated with (i) sea grass meadows (SG) and (ii) coral mounds (CM) consisting of coral bioconstructions with a floatstone/packstone matrix; middle ramp (iii) large rotaliid packstones to wackestone-packstones (LR), (iv) rhodolith floatstone-rudstones (RF), and (v) large lepidocyclinid packstones (LL); and (vi) outer ramp fine-grained bioclastic calcarenites (FC). A total of 38 samples collected from six stratigraphic sections (A, B, D, J, E, LO), measured in the Porto Badisco ravine, were investigated to discriminate the types of porosity. Effective and total porosity was measured using a helium pycnometer. The 3D porosity modelling was performed using PETREL™ 2016 software (Schlumberger). Four main types of porosity were recognized in the carbonates: interparticle, intraparticle, vuggy and mouldic. Primary porosity (inter- and intraparticle) is limited to middle ramp lithofacies (LL and LR) and outer ramp lithofacies (FC), whereas secondary porosity (vuggy and mouldic) was present in both inner ramp lithofacies (CM and SG) and middle ramp red algal lithofacies (RF). In the Porto Badisco carbonates, stratigraphic complexity and the distribution of primary porosity are controlled by lateral and vertical variations in depositional facies. Significant secondary porosity was produced by the dissolution of aragonitic and high-magnesium calcite components, which are dominant in the sea-grass and coral mound facies of the inner ramp and in the rhodolith floatstone-rudstones of the middle ramp. 3D models were developed for both effective and total porosity distribution. The porosity models show a clear correlation with facies heterogeneities. However of the two models, the effective porosity model shows the best correlation with the 3D facies model, and shows a general increase in effective porosity basinwards in the middle ramp facies.     

滨里海盆地肯基亚克地区中、下石炭统碳酸盐岩储层特征与成岩作用

利用岩心、岩矿薄片、扫描电镜、孔渗和地化等多种资料,对滨里海盆地肯基亚克地区A井取心段中、下石炭统碳酸盐岩岩石类型、储集空间和成岩作用进行了研究。研究揭示:中、下石炭统碳酸盐岩为纵向上非均质性强的开阔台地相颗粒灰岩和泥晶灰岩储层,可划分为以粒间溶孔-粒内溶孔为主的Ⅰ类好储层和以晶间孔-晶间溶孔为主的Ⅱ类中等或差储层。胶结作用和溶蚀作用是控制两类储层形成的主要成岩作用,前者主要包括正常海水叶片状-纤维状方解石胶结作用、埋藏期镶嵌状、粒状、半自形方解石胶结作用,后者主要包括大气淡水溶蚀作用和埋藏期溶蚀作用。其中,埋藏期溶蚀作用是形成Ⅰ类储层的关键,Ⅱ类储层则具胶结作用发育的特征。