scholarly journals Diagenesis Processes Impact on Reservoir Quality in Carbonate Yamama Formation /Faihaa Oil Field

2020 ◽  
pp. 92-102
Author(s):  
Mohammed A. Ahmed ◽  
Madhat E. Nasser ◽  
Sameer N. AL Jawad
Keyword(s):  
Oil Field ◽  
Reservoir Quality ◽  
Genetic Classification ◽  
Thin Sections ◽  
Positive Effects ◽  
Diagenetic Processes ◽  
Porosity And Permeability ◽  
Cretaceous Period ◽  
The Impact

The Yamama Formation is a significant reservoir in the southern part of Iraq. This formation consists of limestone deposited throughout the Lower Cretaceous period within main retrogressive depositional series. This study aims to identify the impact of the diagenesis processes on the reservoir’s characteristics (porosity and permeability). Diagenesis processes’ analysis and the identification of Yamama Formation depended on the examination of more than 250 thin sections of the core samples from two wells that were used to determine different diagenetic environments and processes. The three identified diagenetic environments that affected Yamama reservoir were the marine, meteoric and burial environments. Eight diagenetic processes were recognized in Yamama Formation and showed positive and destructive effects on the reservoir quality; Dissolution and fracture had highly positive effects through creating and improving porosity and permeability that led to improving reservoir quality. Cementation and compaction had destructive effects, through reducing porosity and permeability, that led to reducing reservoir quality. Other processes such micritization, dolomitization, bioturbation and neomorphism did not have strong effects on reservoir quality. Based on genetic classification of porosity, most of porosity within Yamama Formation in this field was formed by diagenesis processes, implying that Yamama reservoir is a type of diagenetic reservoir.

scholarly journals Impact of Diagenesis on the Reservoir Properties of the Cretaceous Sandstones in the Southern Bredasdorp Basin, Offshore South Africa

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 757
Author(s):  
Temitope Love Baiyegunhi ◽  
Kuiwu Liu ◽  
Oswald Gwavava ◽  
Christopher Baiyegunhi
Keyword(s):  
Oil And Gas ◽  
Gas Production ◽  
Reservoir Quality ◽  
Reservoir Properties ◽  
Oil And Gas Production ◽  
Thin Sections ◽  
Hydrocarbon Reservoir ◽  
Porosity And Permeability ◽  
The Impact

The Cretaceous sandstone in the Bredasdorp Basin is an essential potential hydrocarbon reservoir. In spite of its importance as a reservoir, the impact of diagenesis on the reservoir quality of the sandstones is almost unknown. This study is undertaken to investigate the impact of digenesis on reservoir quality as it pertains to oil and gas production in the basin. The diagenetic characterization of the reservoir is based on XRF, XRD SEM + EDX, and petrographic studies of 106 thin sections of sandstones from exploration wells E-AH1, E-AJ1, E-BA1, E-BB1 and E-D3 in the basin. The main diagenetic processes that have affected the reservoir quality of the sandstones are cementation by authigenic clay, carbonate and silica, growth of authigenic glauconite, dissolution of minerals and load compaction. Based on the framework grain–cement relationships, precipitation of the early calcite cement was either accompanied or followed up by the development of partial pore-lining and pore-filling clay cements, particularly illite. This clay acts as pore choking cement, which reduces porosity and permeability of the reservoir rocks. The scattered plots of porosity and permeability versus cement + clays show good inverse correlations, suggesting that the reservoir quality is mainly controlled by cementation and authigenic clays.

scholarly journals Linking Depositional Environments and Diagenetic Processes to Porosity Evolution and destruction in the Arab Formation reservoirs, Offshore oilfields of Qatar

2020 ◽  
Author(s):  
Fadhil N. Sadooni ◽  
Hamad Al-Saad Al-Kuwari ◽  
Ahmad Sakhaee-Pour ◽  
Wael S. Matter
Keyword(s):  
Depositional Environments ◽  
Oil Reservoir ◽  
Secondary Porosity ◽  
Future Directions ◽  
Thin Sections ◽  
Intergranular Porosity ◽  
Porosity Evolution ◽  
Diagenetic Processes ◽  
Exploration And Production ◽  
The Impact

Introduction: The Jurassic Arab Formation is the main oil reservoir in Qatar. The Formation consists of a succession of limestone, dolomite, and anhydrite. Materials and methods: A multi-proxy approach has been used to study the Formation. This approach is based on core analysis, thin sections, and log data in selected wells in Qatar. Results: The reservoir has been divided into a set of distinctive petrophysical units. The Arab Formation consists of cyclic sediments of oolitic grainstone/packstone, foraminifera-bearing packstone-wackestone, lagoonal mudstone and dolomite, alternating with anhydrite. The sediments underwent a series of diagenetic processes such as leaching, micritization, cementation, dolomitization and fracturing. The impact of these diagenetic processes on the different depositional fabrics created a complex porosity system. So, in some cases there is preserved depositional porosity such as the intergranular porosity in the oolitic grainstone, but in other cases, diagenetic cementation blocked the same pores and eventually destroyed them. In other cases, diagenesis improved the texture of non-porous depositional texture such as mudstone through incipient dolomitization creating inter-crystalline porosity. Dissolution created vugs and void secondary porosity in otherwise non-porous foraminiferal wackestone and packstone. Therefore, creating a matrix of depositional fabrics versus diagenetic processes enabled the identification of different situations in which porosity was either created or destroyed. Future Directions: By correlating the collected petrographic data with logs, it will become possible to identify certain “facio-diagenetic” signatures on logs which will be very useful in both exploration and production. Studying the micro and nano-porosity will provide a better understanding of the evolution and destruction of its porosity system.

Reservoir Quality of the Miocene Formation Gas Deposits, Onshore Abu Dhabi

2021 ◽  
Author(s):  
Catherine Breislin ◽  
Laura Galluccio ◽  
Kate Al Tameemi ◽  
Riaz Khan ◽  
Atef Abdelaal
Keyword(s):  
Depositional Environment ◽  
Middle Miocene ◽  
Quality Analysis ◽  
Reservoir Quality ◽  
Carbonate Facies ◽  
Pore System ◽  
Thin Sections ◽  
Reservoir Architecture ◽  
Porosity And Permeability ◽  
Permeability Anisotropy

Abstract Understanding reservoir architecture is key to comprehend the distribution of reservoir quality when evaluating a field's prospectivity. Renewed interest in the tight, gas-rich Middle Miocene anhydrite intervals (Anh-1, Anh-2, Anh-3, Anh-4 and Anh-6) by ADNOC has given new impetus to improving its reservoir characterisation. In this context, this study provides valuable new insights in geological knowledge at the field scale within a formation with limited existing studies. From a sedimentological point of view, the anhydrite layers of the Miocene Formation, Anh-1, Anh-2, Anh-3, Anh-4 and Anh-6 (which comprise three stacked sequences: Bur1, Bur2 and Bur3; Hardenbol et al., 1998), have comparable depositional organisation throughout the study area. Bur1 and Bur2 are characterised by an upward transition from intertidal-dominated deposits to low-energy inner ramp-dominated sedimentation displaying reasonably consistent thickness across the area. Bur3 deposits imply an initial upward deepening from an argillaceous intertidal-dominated to an argillaceous subtidal-dominated setting, followed by an upward shallowing into intertidal and supratidal sabkha-dominated environments. This Bur3 cycle thickens towards the south-east due to a possible deepening, resulting in the subtle increase in thickness of the subtidal and intertidal deposits occurring around the maximum-flooding surface. The interbedded relationship between the thin limestone and anhydrite layers within the intertidal and proximal inner ramp deposits impart strong permeability anisotropy, with the anhydrite acting as significant baffles to vertical fluid flow. A qualitative reservoir quality analysis, combining core sedimentology data from 10 wells, 331 CCA data points, 58 thin-sections and 10 SEM samples has identified that reservoir layers Anh-4 and Anh-6 contain the best porosity and permeability values, with the carbonate facies of the argillaceous-prone intertidal and distal inner ramp deposits hosting the best reservoir potential. Within these facies, the pore systems within the carbonate facies are impacted by varying degrees of dolomitisation and dissolution which enhance the pore system, and cementation (anhydrite and calcite), which degrade the pore system. The combination of these diagenetic phases results in the wide spread of porosity and permeability data observed. The integration of both the sedimentological features and diagenetic overprint of the Middle Miocene anhydrite intervals shows the fundamental role played by the depositional environment in its reservoir architecture. This study has revealed the carbonate-dominated depositional environment groups within the anhydrite stratigraphic layers likely host both the best storage capacity and flow potential. Within these carbonate-dominated layers, the thicker, homogenous carbonate deposits would be more conducive to vertical and lateral flow than thinner interbedded carbonates and anhydrites, which may present as baffles or barriers to vertical flow and create significant permeability anisotropy.

scholarly journals Pore-water controlled grain fracturing as an indicator for subglacial shearing in tills

1997 ◽  
Vol 43 (145) ◽  
pp. 446-454 ◽  
Author(s):  
John F. Hiemstra ◽  
Jaap J. M. Van Der Meer
Keyword(s):  
The Netherlands ◽  
Pore Water ◽  
Genetic Classification ◽  
Glacial Deposits ◽  
Thin Sections ◽  
Glacial Sediments ◽  
Fracturing Process

AbstractGenetic classification of glacial deposits still proves to be highly controversial. In many cases, it remains unclear whether a particular sediment has been sub-glacially deformed. In the present paper it is suggested that micromorphological research is helpful where current techniques fail to lead to unambiguous interpretations. It is argued that the occurrence of fractured grains in glacial sediments is indicative of subglacial shearing and that such grains may be used as diagnostic evidence of glaciotectonism. Deformational mechanisms associated with the fracturing process are outlined and explained, using a series of thin sections from Wijnjewoude, The Netherlands.

scholarly journals Experimental Investigation of the Effects of Water and Polymer Flooding on Geometric and Multifractal Characteristics of Pore Structures

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5288
Author(s):  
Xianguo Zhang ◽  
Chengyan Lin ◽  
Yuqi Wu ◽  
Tao Zhang ◽  
Hongwei Wang ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Total Porosity ◽  
Polymer Flooding ◽  
Oil Field ◽  
Water Flooding ◽  
Reservoir Quality ◽  
Thin Sections ◽  
X Ray ◽  
Pore Structures

During water and polymer flooding for enhanced oil recovery, pore structures may vary because of the fluid–rock interactions, which can lead to variations in petrophysical properties and affect oil field production. To investigate the effects of fluid flooding on pore structures, six samples were subjected to brine water, dual-system, and alkaline–surfactant–polymer (ASP) polymer displacement experiments. Before and after experiments, samples were scanned by X-ray CT. Thin sections, X-ray diffraction, and high pressure mercury injection tests were also carried out to characterize mineralogy and fractal dimension of pore systems before experiments. Experiment results show that water flooding with low injection pore volume ratio (IPVR) can improve reservoir quality since total porosity and connected porosity of samples rise after the flooding and the proportion of large pores also increases and heterogeneity of pore structure decreases. However, water flooding with high IPVR has reverse effects on pore structures. Polymer flooding reduces the total porosity, connected porosity, the percentage of small pores and enhances the heterogeneity of pore structures. It can be found that pore structures will change in fluid flooding and appropriate water injection can improve reservoir quality while excessive water injection may destroy the reservoir. Meanwhile, injected polymer may block throats and destroy reservoirs. The experimental results can be used as the basis for oil field development.

scholarly journals Diagenesis and Thermal Maturity of the Cogollo Group rocks in the ANH-CR-Montecarlo-1X well, Cesar-Ranchería Basin, Colombia

2021 ◽  
Vol 48 (3) ◽  
Author(s):  
Carlos A Ríos ◽  
Mayra A Vargas ◽  
Mario García
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Temporal Distribution ◽  
Thermal Maturity ◽  
Secondary Porosity ◽  
Diagenetic Processes ◽  
Geological Unit ◽  
Porosity And Permeability ◽  
The Impact ◽  
Ferrous Carbonate

In ANH-CR-Montecarlo-1X well located in the southern sector of the Cesar-Ranchería basin, Colombia, rocks of the middle Cretaceous outcrop, which have been defined as belonging to the Cogollo Group. The present study concerns with the diagenetic evolution and thermal maturity of this geological unit, integrating petrographic techniques (thin section microscopy and scanning electron microscopy), geochemistry (total organic carbon and pyrolysis rock-eval) and basic petrophysics, to establish the thermal maturity and the potential of rocks as reservoirs of conventional and unconventional hydrocarbons. The results of petrographic and diagenetic analysis revealed that the rocks compositionally correspond to quartz sandstones and graywackes and carbonate rocks to mudstones and wackestones; which were affected by diagenetic processes such as compaction, mineral neoformations distinguishing minerals from the group of clays that cover the grains of the framework, and other types of precipitates of cements such as silica, ferrous and non-ferrous carbonate, some of these present partial and/or total dissolution, for which secondary porosity is recognized, also metasomatisms, where processes of chloritization and illitization of the argillaceous matrix are observed, alteration of feldspars to ferrous and non-ferrous carbonate, which affects the porosity and permeability of the rock; and recrystallization from micrite to sparite and carbonate precipitation in calcareous rocks. The study also showed that the rocks were more affected by compaction than precipitation of the different cements. The research contributes to the understanding of the impact of diagenetic processes on porosity, as well as their spatial and temporal distribution, providing diagenetic paragenesis for both siliciclastic and carbonatic rocks. When we classifying siliciclastic rocks as potential reservoir rocks, low potential results were obtained as conventional reservoirs but has good potential as non-conventional reservoirs (tight sandstones), this respect to porosity and permeability data. The geochemical studies in the calcareous rocks exhibited low to good content of total organic carbon, overmaturity state and a low generation potential with type III and IV kerogens.

scholarly journals Alguns parâmetros utilizados na avaliação hidrogeoquímica de um campo petrolífero na Bacia de Campos (RJ): estudos preliminares

1994 ◽  
Vol 17 ◽  
pp. 132-156
Author(s):  
Sergio Luiz Nogueira de Azevedo ◽  
Carla Valéria Martins Rodrigues ◽  
Antonio Carlos Jacome de Castro
Keyword(s):  
Clay Minerals ◽  
Oil Field ◽  
Formation Water ◽  
Circulation Zone ◽  
Isotopic Data ◽  
Genetic Classification ◽  
Strong Point ◽  
Campos Basin ◽  
Basic Facts

The study of the formation water is receiving a great importance, as a tool in the studies of migration, weathering and accumulation of hidrocarbons. The present study is based on the interpretation of chemical and isotopic data of formation water belonging to Lagoa Feia and the Macae Formations of the Campos Basin oil field. The purpose of mecanisms for evolution and genetic classification of formation water, that was intended in the recent study, determined theirs sources and hydrogeological environments in question. Finnaly, these basic facts were related with the possibility, or not, of accumulation of hydrocarbons. The sample from Campo X point towards existence of "stagnated environments" with low circulation of water, inclined for accumulation of hydrocarbons, shuting out sample 4 (four), belong to Lagoa Feia Formation, is described how indued in the hydrodinamic circulation zone. The strong point of dolomitization and water reaction with clay minerals shows an influence of the meteoric diagenetic environments, proving that before the establishment of estagnated condition observed, probably the water of Campo X received a strong meteoric influence. The waters studied are resulted of one mixture of waters from different brines among these waters originated by evaporation are included. It's possible, because high brines of Lagoa Feia Formation could have some vulcanic contribution.

scholarly journals Impact of diagenesis on the spatial and temporal distribution of reservoir quality in the Jurassic Arab D and C members, offshore Abu Dhabi oilfield, United Arab Emirates

GeoArabia ◽  
2012 ◽  
Vol 17 (3) ◽  
pp. 17-56
Author(s):  
Sadoon Morad ◽  
Ihsan S. Al-Aasm ◽  
Fadi H. Nader ◽  
Andrea Ceriani ◽  
Marta Gasparrini ◽  
...  
Keyword(s):  
Fluid Inclusion ◽  
United Arab Emirates ◽  
Temporal Distribution ◽  
Abu Dhabi ◽  
Reservoir Quality ◽  
Second Phase ◽  
Burial History ◽  
Burial Diagenesis ◽  
Thin Sections ◽  
The Impact

ABSTRACT This study is based on petrographic examination (optical, scanning electron microscope, cathodo-luminescence, backscattered electron imaging, and fluorescence) of 1,350 thin sections as well as isotopic compositions of carbonates (172 carbon and oxygen and 118 strontium isotopes), microprobe analyses, and fluid inclusion microthermometry of cored Jurassic Arab D and C members from 16 wells in a field from offshore Abu Dhabi, United Arab Emirates. The formation was deposited in a ramp with barrier islands and distal slope setting. Petrographic, stable isotopic and fluid-inclusion analyses have unraveled the impact of diagenesis on reservoir quality of Arab D and C within the framework of depositional facies, sequence stratigraphy, and burial history. Diagenetic processes include cementation by grain rim cement and syntaxial calcite overgrowths, formation of moldic porosity by dissolution of allochems, dolomitization and dolomite cementation, cementation by gypsum and anhydrite, and stylolitization. Partial eogenetic calcite and dolomite cementation has prevented porosity loss in grainstones during burial diagenesis. Dolomitization and sulphate cementation of peritidal mud are suggested to have occurred in an evaporative sabkha setting, whereas dolomitization of subtidal packstones and grainstones was driven by seepage reflux of lagoon brines formed during major falls in relative sea level. Recrystallization of dolomite occurred by hot saline waters (Th 85–100°C; and salinity 14–18 wt% NaCl). Anhydrite and gypsum cements (Th 95–105°C; fluid salinity 16–20 wt% NaCl), were subjected to extensive dissolution, presumably caused by thermal sulfate reduction followed by a major phase of oil emplacement. The last cement recorded was a second phase of anhydrite and gypsum (Th 95–120°C; 16–22 wt% NaCl), which fills fractures associated with faults.

DETRITAL AND AUTHIGENIC MINERALOGY OF THE PRETTY HILL FORMATION IN THE PENOLA TROUGH, OTWAY BASIN: IMPLICATIONS FOR FUTURE EXPLORATION AND PRODUCTION

1995 ◽  
Vol 35 (1) ◽  
pp. 538 ◽  
Author(s):  
B. M. Little ◽  
S. E. Phillips
Keyword(s):  
Reservoir Quality ◽  
Secondary Porosity ◽  
Water Contact ◽  
Thin Sections ◽  
Authigenic Minerals ◽  
Wide Range ◽  
Resistivity Logs ◽  
Exploration And Production ◽  
Reservoir Sandstones ◽  
The Impact

The Pretty Hill Formation in the Penola Trough is a productive gas reservoir in the Katnook, Ladbroke Grove and Haselgrove fields. Thin sections, X-ray diffraction, scanning electron micros­copy and electron microprobe analyses have been used to characterise the mineralogy of core samples from eight wells. The reservoir sandstones are typically fine to medium grained, moderately sorted feldspathic litharenites. Framework grains comprise detrital quartz, feldspars (albite, microcline and anorthite), lithics (dominantly volcanic), mica and accessory minerals. Authigenic minerals of chlorite, laumontite, carbonate, quartz, feldspar, sphene, anatase, glaucony and illite are present in all wells. Kaolinite is restricted to Ladbroke Grove-1. Chlorite, laumontite and carbonate are volumetrically the most important authigenic minerals.There is a wide range in core plug porosity (one to 23 per cent) and permeability (10"3to 103 md) in the reservoir sandstones. In samples with high per­centages of authigenic clays microporosity is im­portant. Regional trends indicate reservoir quality decreases with increasing depth but superimposed on this trend is the influence of the detrital and authigenic mineralogy. Cleaner, coarser sublitharenites and subarkoses have good reservoir char­acteristics but where lithics concentrate in the finer feldspathic litharenites and litharenites deformation of these ductile grains has limited porosity and permeability. Authigenic minerals have both reduced and enhanced reservoir quality. Chlo­rite rims with associated microporosity have decreased the impact of mechanical compaction and inhibited silicification. Pore filling cements of laumontite and carbonate have occluded intergranular pores and replaced grains. Secondary porosity produced by the dissolution of these cements in the gas zones has significantly improved reservoir quality.Other information gained from the mineralogical study could influence future exploration and production. Lack of contrast on resistivity logs between gas and water zones is not due to the mineralogy of the Pretty Hill Formation. However, the restriction of early diagenetic laumontite to the water zones of gas producing wells does indicate the location of the gas-water contact. Laumontite was dissolved from the gas zone by an increase in C02 prior to hydrocarbon migration. Use of acids to enhance permeability in the Pretty Hill Formation should take into account the probable formation damage caused by reactions with the clays. Kaolin- ite could dissolve to produce a silica gel and the high Fe3+ content of the chlorite will result in a gel unless iron chelators are used in the mud acid. The depositional environment of the Pretty Hill Forma­tion has historically been interpreted as braided fluvial stream deposits interfingering with finer grained lacustrine shales and siltstone. However, this model can not explain the presence of glaucony grains, unless the glaucony has been reworked, but there is no unequivocal evidence to support this hypothesis.

scholarly journals The Influence of Magmatic Intrusions on Diagenetic Processes and Stress Accumulation

Geosciences ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 477 ◽  
Author(s):  
Magnhild Sydnes ◽  
Willy Fjeldskaar ◽  
Ivar Grunnaleite ◽  
Ingrid Fjeldskaar Løtveit ◽  
Rolf Mjelde
Keyword(s):  
Numerical Study ◽  
Sedimentary Basins ◽  
Reservoir Quality ◽  
Hydrocarbon Migration ◽  
Hydrocarbon Reservoir ◽  
Hydrocarbon Traps ◽  
Diagenetic Processes ◽  
Porosity And Permeability ◽  
Magmatic Intrusions ◽  
Stress Accumulation

Diagenetic changes in sedimentary basins may alter hydrocarbon reservoir quality with respect to porosity and permeability. Basins with magmatic intrusions have specific thermal histories that at time of emplacement and in the aftermath have the ability to enhance diagenetic processes. Through diagenesis the thermal conductivity of rocks may change significantly, and the transformations are able to create hydrocarbon traps. The present numerical study quantified the effect of magmatic intrusions on the transitions of opal A to opal CT to quartz, smectite to illite and quartz diagenesis. We also studied how these chemical alterations and the sills themselves have affected the way the subsurface responds to stresses. The modeling shows that the area in the vicinity of magmatic sills has enhanced porosity loss caused by diagenesis compared to remote areas not intruded. Particularly areas located between clusters of sills are prone to increased diagenetic changes. Furthermore, areas influenced by diagenesis have, due to altered physical properties, increased stress accumulations, which might lead to opening of fractures and activation/reactivation of faults, thus influencing the permeability and possible hydrocarbon migration in the subsurface. This study emphasizes the influence magmatic intrusions may have on the reservoir quality and illustrates how magmatic intrusions and diagenetic changes and their thermal and stress consequences can be included in basin models.

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