scholarly journals Modeling the processes of deformation and destruction of the rock sample during its extraction from great depths

2021 ◽  
Vol 248 ◽  
pp. 243-252
Author(s):  
Alexey Grishchenko ◽  
Artem Semenov ◽  
Boris Melnikov
Keyword(s):  
Mechanical Properties ◽  
Oil And Gas ◽  
Rock Sample ◽  
Geological Exploration ◽  
Reservoir Properties ◽  
Critical Dimensions ◽  
Reservoir Rocks ◽  
Rock Samples ◽  
Porosity And Permeability

Article investigates the change in the geophysical properties of rocks in the process of extracting the rock sample from great depths. Evaluation of changes in effective elastic properties, porosity and permeability of rock samples during extraction was carried out by means of finite element modeling. Assessment of the critical dimensions and orientation of internal defects, leading to the destruction of the rock samples during extraction from great depths, has been made based on the methods of linear destruction mechanics. Approach that makes it possible to calculate the change in the mechanical properties, porosity and fracturing of reservoir rocks in the process of extracting the rock sample from depths to the surface is proposed. Use of refined data on the mechanical properties of recoverable rock samples makes it possible to increase the accuracy of digital geological models required for geological exploration, determination of reservoir properties and oil and gas saturation of a field, and development of oil and gas deposits. Application of such models is especially relevant at all stages of the fields development with hard-to-recover reserves.

scholarly journals PETROGRAPHIC CHARACTERISTICS OF THE RESERVOIR ROCKS IN THE BAT-UPPER JURASSIC DEPOSITS OF THE SOUTH OF WESTERN-SIBERIAN PETROLEUM BASIN

2019 ◽  
Vol 2 (1) ◽  
pp. 25-31
Author(s):  
Lyudmila Vakulenko ◽  
Aleksey Popov ◽  
Sergey Rodyakin ◽  
Evgeniy Khabarov ◽  
Peter Yan
Keyword(s):  
Oil And Gas ◽  
Upper Jurassic ◽  
The South ◽  
Reservoir Properties ◽  
Petrographic Composition ◽  
Reservoir Rocks ◽  
Regional Sources ◽  
Porosity And Permeability ◽  
Maximum Parameters ◽  
Petroleum Basin

The features of the petrographic composition of the bath-upper Jurassic silt-sand rocks exposed by wells in the South of the West Siberian oil and gas basin are considered. The study is focused on the parameters that had a significant influence on the reservoir properties of rocks: granulometric and mineral-petrographic composition of the clastic part of rocks, cement content, structure and composition. Some conclusions are drawn on the spatial distribution of rocks of different composition within the subisochronous sedimentary complexes. It is assumed that significant variations in their composition are caused by a complex combination of varying degrees of interdependent factors: influence of local and regional sources of clastic material, peculiarities of redistribution of material during its transportation and sedimentation, and post-sedimentation changes. Most variable values of reservoir properties, with a recorded maximum parameters of porosity and permeability are obtained for the rocks of Medium-Upper Oxford complex on Verkhnetarskaya, Dedovskaya, Basinskaya, Veselovskaya, to a lesser extent, Kasmanskaya, Vostochnaya and Tai-Dasskaya drilling sites.

scholarly journals Spatial distribution of Permian-Triassic deposits of the Eastern Ciscaucasia and their oil and gas potential

2020 ◽  
Author(s):  
М.А. Хасанов ◽  
Т.Б. Эзирбаев ◽  
А.С. Эльжаев
Keyword(s):  
Oil And Gas ◽  
Middle Triassic ◽  
Lower Triassic ◽  
Comprehensive Analysis ◽  
Carbonate Content ◽  
Propagation Time ◽  
Well Testing ◽  
Geological Exploration ◽  
Reservoir Properties ◽  
Reservoir Rocks

Изучаемой проблемы заключается в том, что месторождения нефти и газа Восточного Предкавказья являются одними из самых длительно разрабатываемых в России. Однако в настоящее время, когда объем геологоразведочных работ на нефть и газ значительно снизился, прирост запасов УВ сократился до минимума. Но по оценкам различных геологических служб РФ, в глубокопогруженных пермо-триасовых отложениях Восточного Ставрополья и Равнинного Дагестана еще может содержаться значительный объем углеводородного сырья. И для определения правильного комплекса геологоразведовательных работ на нефть и газ необходим комплексный анализ всех геологических и промыслово-геофизических материалов, результатов лабораторного анализа петрофизических свойств, обобщение и ревизия результатов опробования и испытания карбонатных отложений изучаемых отложений с целью выявления закономерностей развития коллекторов. В связи с этим выполнение данной работы в настоящее время является актуальной задачей.Цель работы – обобщить многочисленные исследования по изучению литолого-петрографических особенностей отложений Пермо-триасового комплекса Восточного Предкавказья и его битуминологической характеристике, которые говорят о том, что в разрезе его имеются мощные толщи пород, обладающие богатым потенциалом генерации жидких и газообразных углеводородов. В первую очередь, к ним следует отнести карбонатные и карбонатно-терригенные породы нижнего-среднего триаса морского генезиса (Нефтекумская, Култайская, Демьяновская и Кизлярская свиты). Существенный объем углеводородов могли генерировать и карбонатно-терригенные и терригенные пестроцветные породы среднего триаса лагунно-морского и лагунно-континентального генезиса (Плавненская и Закумская свиты), а также терригенная пестроцветная толща пород верхней Перми преимущественно морского генезиса (Куманская свита). Методы исследования. В статье рассмотрены проблемы расчленения разреза на пласты и выделения коллекторов, оценки их фильтрационно-емкостных свойств пород-коллекторов, обоснования нефтегазонасыщенности и проницаемости продуктивных пластов. Для установления закономерностей распространения коллекторов и составления рекомендаций на проведение геологоразведочных работ, направленных на поиск нефти и газа в изучаемом нефтегазоносном комплексе был выполнен анализ литофациальных, петрофизических и емкостно-фильтрационных свойств пород-коллекторов в разрезе нижнетриасовых отложений нефтекумской свиты Восточного Ставрополья. В работе так же приведены результаты геофизических и лабораторных исследований, которые содержат данные о петрофизических и физико-химических свойствах изучаемых пород отложений нижнего триаса: пористость; объемный вес; карбонатность; коэффициент гидрофобности, удельное электрическое сопротивление; интервальное время распространения упругих продольных волн. Результаты исследования. Из комплексного анализа распределения головных петрофизических параметров и результатов испытания скважин видно, что лишь на юго-востоке получены притоки нефти из карбонатных коллекторов нефтекумской свиты. В области хемогенного (доломитового) карбонатонакопления продуктивными являются XI-XII пласты средней подсвиты, в области массового развития биогермных построек и межрифовых понижений продуктивными являются I-VI пласты нефтекумской свиты. В областях мелководного карбонатонакопления находятся водонасыщенные коллектора The urgency of the studied problem lies in the fact that the oil and gas fields of the Eastern Ciscaucasia are one of the longest developed in Russia. However, at present, when the volume of exploration for oil and gas has significantly decreased, the increase in hydrocarbon reserves has decreased to a minimum. But according to estimates of various geological services of the Russian Federation, in the deeply submerged Permo-Triassic sediments of the East Stavropol and Plain Dagestan, a significant amount of hydrocarbon raw materials may still be contained. And to determine the correct complex of geological exploration for oil and gas, a comprehensive analysis of all geological and field geophysical materials, results of laboratory analysis of petrophysical properties, generalization and revision of the results of testing and testing of carbonate deposits of the studied deposits in order to identify patterns of reservoir development are necessary. In this regard, the implementation of this work is currently an urgent task.The purpose of the work is to summarize numerous studies on the lithological and petrographic features of the Permian-Triassic deposits of the Eastern Ciscaucasia and its bituminological characteristics, which indicate that it contains powerful rock strata with a rich potential for generating liquid and gaseous hydrocarbons. First of all, these include carbonate and carbonate-terrigenous rocks of the Lower-Middle Triassic of marine origin (Neftekumskaya, Kultayskaya, Demyanovskaya and Kizlyarskaya suites). A significant amount of hydrocarbons could be generated by both carbonate-terrigenous and terrigenous variegated rocks of the Middle Triassic of the lagoon-marine and lagoon-continental genesis (Plavnenskaya and Zakumskaya Formations), as well as terrigenous variegated strata of rocks of the upper Perm mainly of the marine genesis (Kuman Formation).Research Methods.The article discusses the problems of dividing a section into formations and separating reservoirs, assessing their filtration and reservoir properties of reservoir rocks, substantiating oil and gas saturation and permeability of productive formations. In order to establish the patterns of reservoir distribution and make recommendations for geological exploration aimed at finding oil and gas in the studied oil and gas complex, the lithofacial, petrophysical, and capacitive-filtration properties of reservoir rocks were analyzed in the context of the Lower Triassic sediments of the Neftekum Formation. The paper also presents the results of geophysical and laboratory studies, which contain data on the petrophysical and physico-chemical properties of the studied rocks of the Lower Triassic sediments: porosity; volume weight; carbonate content; hydrophobicity coefficient, electrical resistivity; interval propagation time of elastic longitudinal waves.The results. From a comprehensive analysis of the distribution of the leading petrophysical parameters and the results of well testing, it is clear that oil flows from the carbonate reservoirs of the Neftekum Formation were obtained only in the southeast. In the area of chemogenic (dolomitic) carbonate accumulation, the XI-XII layers of medium subformation are productive, in the field of mass development of bioherm constructions and inter-riff depressions, I-VI layers of the Neftekum suite are productive. In areas of shallow carbonate accumulation are water-saturated reservoirs

scholarly journals RESULTS OF PETROPHYSICAL STUDIES OF THE PRODUCTIVE STRATUM DEPOSITS OF THE BAKU ARCHIPELAGO NORTHERN OIL AND GAS BEARING AREAS

2020 ◽  
pp. 22-27
Author(s):  
V. Sultanov ◽  
L. Sultanov
Keyword(s):  
Granulometric Composition ◽  
Oil And Gas ◽  
Physical Parameters ◽  
Reservoir Properties ◽  
Secondary Porosity ◽  
North West ◽  
Productive Stratum ◽  
Porosity And Permeability ◽  
The Individual ◽  
Lithological Composition

The complex results of petrophysical testing of rocks, taken from prospecting-development wells of Duvanni-deniz, Sangachal-deniz, Bulla-deniz, Garasu and etc. areas, where the sediments of productive stratum are widely expanded, have been given. Average values of granulometric composition of rocks of productive unit of the above areas by the section have been recounted. The problem of dependence of permeability on porosity and depth was solved. Dependence between physical parameters for the individual kinds of rocks, dependence between physical properties and material structures are established. The results of various petrophysical research methods show that the filtration capacitance properties, in general, deteriorate with depth. However, in certain cases, in clay and carbonate rocks, reservoir properties can improve, due to the appearance of secondary porosity under relatively stringent thermobaric conditions. The histograms, which consist of average values of granulometric composition of productive stratum rocks when crossing some places of archipelago are constructed, the problems of dependence of permeability on porosity and depth were solved. The researches showed, that the physical process of the same- named and same-aged features rocks change in the result of geological-physical processes, getting different values. It's noticed, that the porosity and permeability are increasing from north-west to south-east by changing lithological composition.

scholarly journals Improvement of aspiration thermal massometry method for determination of forms and types of water binding in rocks

2020 ◽  
pp. 39-50
Author(s):  
N.A. Skibitskaya ◽  
V.A. Kuzmin ◽  
M.N. Bolshakov ◽  
O.O. Marutyan ◽  
E.G. Domanova
Keyword(s):  
Measurement Accuracy ◽  
Oil And Gas ◽  
Rock Sample ◽  
Air Flow ◽  
Laboratory Unit ◽  
Water Binding ◽  
Water Saturated

The existing laboratory unit of aspiration thermal massometry, based on the measurement of weight and temperature during drying of rock sample in the air flow, meets the petrophysical tasks of studying oil and gas collectors. At the same time, it has the potential to improve the research accuracy. The paper proposes a modernized facility for studying properties of water-saturated and hydrocarbon-saturated rocks, which due to its design increases measurement accuracy.

scholarly journals MAIN FACTORS THAT CONTROL THE DISTRIBUTION OF THE BASIC TYPES OF SECONDARY CHANGES OF RESERVOIR ROCKS

2017 ◽  
pp. 44-47
Author(s):  
A. V. Podnebesnykh ◽  
A. R. Khafizov
Keyword(s):  
Distribution Pattern ◽  
Western Siberia ◽  
Oil And Gas ◽  
Pore Space ◽  
Regional Distribution ◽  
Geological Exploration ◽  
Reservoir Rocks ◽  
Oil And Gas Resources ◽  
Main Factors ◽  
Regional Distribution Pattern

Secondary changes in reservoir rocks in the territory of Western Siberia have a regional distribution pattern, and the amount of oil and gas resources, that are in these zones, reaches 30 % of their total number. Part of the objects where the secondary changes are most clearly manifested, has not yet been introduced into the development, what requires a more detailed approach to planning and conducting geological exploration work in perspective areas, where pore space is modified by secondary processes. In this work the main factors that control the distribution of the main types of secondary changes in reservoir rocks were identified: lithofacies, chemical and tectonic.

scholarly journals Technique of Allocation of Reservoirs of Alb-Aptsky Deposits of Tersko-Sunzhensky Oil and Gas-Bearing Areas

2019 ◽  
Author(s):  
И.А. Керимов ◽  
Т.Б. Эзирбаев ◽  
А.С. Эльжаев
Keyword(s):  
Oil And Gas ◽  
Rapid Development ◽  
Experimental Studies ◽  
Economic Feasibility ◽  
Silty Clay ◽  
Boundary Values ◽  
Reservoir Properties ◽  
Geological Characteristics ◽  
Wide Range

Выделение коллекторов нефти и газа и определение эффективных мощностей является важнейшим этапом при подсчете запасов нефти и газа. От результатов, полученных на данном этапе, напрямую зависит экономическая целесообразность ввода в эксплуатацию интервала, обладающего, признаками коллектора, фильтрационными характеристиками. Пределам таких характеристик коллекторов соответствуют кондиционные граничные значения, эти значения являются условными и могут меняться, исходя из технического уровня разработки месторождений нефти или газа на момент проведения исследований. В современных условиях быстрого развития совершенных методов разработки и изменением экономических запросов кондиционные граничные значения изменяются довольно в широких пределах. Альб-аптские отложения Терско-Сунженской нефтегазоносной области (ТСНО) относятся к сложным типам порово-трещинного коллекторов, и представлены породами песчано-алеврито-глинистых компонент. Экспериментальные исследования, проведенные на образцах кернов, взятых из терригенных отложений ТСНО позволили установить основные особенности этих отложений, обосновать основные петрофизические зависимости и определить их коллекторские свойства. В разрезе альб-аптских отложений Терско-Сунженской нефтегазоносной области в 1960-70-х гг. по известным методикам были выделены пласты-коллекторы и определены эффективные мощности. В 20092012 гг. была проведена переинтерпретация фондовых материалов результатов данных ГИС и лабораторного анализа кернов из ряда скважин основных пробуренных на нижнемеловые отложения ТСНО и предложена более совершенная методика обработки и интерпретации данных ГИС терригенных пород. В данной работе рассмотрены ранее применявшаяся методика и пример интеграции методики выделения коллекторов на основе технологии обработки и интерпретации данных ГИС ТАВС в нижнемеловых терригенных отложениях ТСНО. Важной особенностью методики комплексной интерпретации, реализованной в технологии ESKS автоматизированной системы обработки и интерпретации данных геофизических исследований скважин Gintel, является определение широкого спектра петрофизических параметров, характеризующих литологическую и флюидальную неоднородность изучаемых отложений. Это позволяет более обосновано решать задачи разведки и разработки месторождений. Методика интерпретации данных ГИС ТАВС обеспечивает определение набора геологических характеристик пород, используя которые можно определить геологическую неоднородность изучаемой толщи пород, построить детальную трехмерную геологическую модель всех продуктивных пластов в разрезе и определить их подсчетные параметры. Детальность определения геологических характеристик пород напрямую зависит от комплекса данных каротажа, зарегистрированных в скважинах. Однако особенностью методики ТАВС является то, что в ней используются системы петрофизических моделей и алгоритмические приемы обработки, которые позволяют получить максимум геологической информации об изучаемых породах даже при ограниченном комплексе данных ГИС The selection of oil and gas reservoirs and the determination of effective capacities is a critical step in calculating oil and gas reserves. From the results obtained at this stage, the economic feasibility of putting into operation an interval having, with the signs of a collector, filtration characteristics, directly depends. The limits of such reservoir characteristics correspond to conditional boundary values, these values are conditional and may vary based on the technical level of development of oil or gas fields at the time of the study. In modern conditions of rapid development of perfect development methods and changing economic demands, conditional boundary values vary quite widely. Alb-Aptian oil deposits of the Tersko-Sunzhensky oil and gas region (TSOGR) are complex types of pore-fracture reservoirs and are represented by rocks of sandy-silty-clay components. Experimental studies conducted on core samples taken from terrigenous sediments of TSOGR allowed us to establish the main features of these deposits, substantiate the main petrophysical dependencies and determine their reservoir properties. In the context of the Alb-Aptian sediments of the Tersko-Sunzhenskoye oil and gas region, by known methods, reservoirs were identified and effective thicknesses determined. In 2009-2012 reinterpretation of the stock materials of the results of well logging data and laboratory analysis of cores from a number of wells of the main fields drilled on the Lower Cretaceous deposits of TCHW was carried out and a better method for processing and interpretation of well log data of terrigenous rocks was proposed. An important feature of the integrated interpretation methodology implemented in ESKS technology of the Gintel automated geophysical data processing and interpretation system is the determination of a wide range of petrophysical parameters characterizing the lithological and fluid heterogeneity of the researched deposits. This allows us to more reasonably solve the problems of exploration and development of deposits. The technique of interpreting the GIS TABC data provides the determination of geological characteristics set for rocks, using which it is possible to determine the geological heterogeneity of the researched rock stratum, to develop a detailed three-dimensional geological model of all productive formations in a section and determine their estimated parameters. The detail of determining the geological characteristics of the rocks directly depends on the complex of logging data recorded in the wells. However, a feature of the TABC technique is that it uses systems of petrophysical models and algorithmic processing techniques that allow one to get the maximum geological information about the researched rocks even with a limited set of GIS data

The insensitivity of thermal diffusivity of natural sediments to saturation

2018 ◽  
Vol 58 (2) ◽  
pp. 705
Author(s):  
Ayman Ezdini ◽  
James Griffith ◽  
Nick Lange ◽  
Soroush Tehrani ◽  
Hamad Roshan ◽  
...  
Keyword(s):  
Grain Size ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Clay Content ◽  
Heat Diffusion ◽  
Reservoir Properties ◽  
Needle Probe ◽  
Close Relationship ◽  
Porosity And Permeability

This extended abstract presents a ground-breaking study of thermal properties of soils and their dependency on saturation. The paper tries to prove that thermal diffusivity is not significantly dependent on saturation due to its close relationship with saturation-independent parameters such as thermal conductivity and volumetric heat capacity. The investigation is divided into two main scopes of work: the first is to build statistical analysis using the Monte Carlo technique by means of random sampling certain soil thermal properties; and the second is to experimentally validate the statistical models. The experimental framework of the study encompasses the measurement of thermal properties of different soil samples. These samples varied in terms of grain size, percentage clay content, and level of saturation. The experiments were carried out using a KD2-Pro Dual Needle Probe Thermal Properties Analyser. The results demonstrate that saturation has a negligible effect on thermal diffusivity of soils but an inverse relationship exists between diffusivity and clay content. Furthermore, the variation in grain size effect on diffusivity is within 5%. The study shows a correlation between lithology, porosity, and thermal properties. The implications are numerous: from the determination of unwanted heat diffusion of pipelines to the estimation of reservoir properties such as porosity and permeability.

scholarly journals NEW DATA ON PROMISING OIL AND GAS OBJECTS IN THE SANDSTONES OF THE YAMNA SUITE OF THE PALEOCENE IN THE NORTHWEST OF THE SKIBA ZONE OF THE UKRAINIAN CARPATHIANS

2021 ◽  
pp. 90-110
Author(s):  
V.Ye. Shlapinskiy ◽  
H.Ya. Havryshkiv ◽  
Yu.P. Haievska
Keyword(s):  
Oil And Gas ◽  
Gas Production ◽  
Oil Field ◽  
Distribution Area ◽  
Total Production ◽  
Reservoir Properties ◽  
Oil And Gas Production ◽  
The North ◽  
Natural Oil ◽  
Porosity And Permeability

More than 6 million tons of the oil have been extracted in the Skybа Zone of the Ukrainian Carpathians. In particular, 4.2 million tons of oil (85.7% of total production) were obtained from the Yamna sandstones of Paleocene, which are characterized by satisfactory physical properties. Most of the areas of fields that exploited them are located in the Boryslav oil and gas production area. Among them are such oil fields as Skhidnytsko-Urytske (more than 3.8 million tons of oil extracted), Violeta, Faustina, MEP, Miriam and Ropne. Outside this area, oil was extracted in Strilbychi and Staraya Sol. At most of these fields, oil horizons are at a depth of only 100-800 m. The gas and condensate are extracted at the field of Tanyavа in the wing of the Vytvytska Luska of the Berehova Skyba, which has been torn off by the thrust. In addition, a very large number of natural oil and gas manifestations - direct signs of oil and gas potential - have been recorded in the Skyba Zone. All this indicates the potential prospects of structures within the Skyba Zone, including shallow ones. The distribution area of Yamna sandstones is much larger than the area of these deposits. The distribution area of sandstones of Yamna is much larger than the area of these deposits. It occupies about half of the area of Skyba Zone. Part of it can be considered promising, removing areas where of Yamna sandstones are present on the day surface, although, even in such conditions, they are in some cases industrially oil-bearing (Strelbychi oil field). Sandstones of Yamna are characterized by satisfactory reservoir properties., The calculated porosity and permeability reach the maximum values at known deposits: 0.182 and 130 ∙ 10–3 microns2 respectively, and the estimated thickness of 13.5 m. In the Folded Carpathians and, especially, within the north-eastern fragments (Beregova, Oriv, Skoliv) in different years performed a large amount of field seismic surveys. On the basis of the obtained materials, for the first time in the Carpathian region structural constructions were made on the reflecting horizons in the Paleocene (Yamna Formation) and in the Stryi Formation of the Upper Cretaceous. This article evaluates the prospects of these research objects. The Khodkiv and Osichnyanska structures of Berehova Skyba are recommended for conducting search works.

scholarly journals THE INFLUENCE OF SEDIMENTATION AND POST-SEDIMENTATION TRANSFORMATIONS ON THE RESERVOIR PROPERTIES OF THE ROCKS

2019 ◽  
pp. 14-19
Author(s):  
V. Khomyn ◽  
M. Maniuk ◽  
O. Maniuk ◽  
A. Popluiko ◽  
N. Khovanets
Keyword(s):  
Oil And Gas ◽  
Scientific Evidence ◽  
Gas Content ◽  
High Porosity ◽  
Reservoir Properties ◽  
Quartz Content ◽  
Positive Correlation ◽  
Median Diameter ◽  
Porosity And Permeability ◽  
Cover Thickness

The topicality of the research is proved by the scientific evidence of the peculiarities of the sedimentation and post-sedimentation transformations of the rocks in relation to their possible oil and gas content. The productive sediments of the deposits of the interior of the Precarpathian Depression were thoroughly and lithologically researched. The objective implied the study and recognition of the reservoir properties within primary (sedimentation) and secondary (post-sedimentation) factors. The primary ones are as follows: granulity (grains median diameter), sorting, and rock maturity. Consequently, a positive correlation between the grains median diameter and rock porosity has been determined; the very coefficient equals 0.56. Evidently, unlike the well-sorted sandstones, the badly graded ones are marked by poor porosity and permeability. The positive correlation between porosity and clastic quartz content is revealed: should the latter increase, the former will go up as well. Apparently, more mature sandstones are characterized by dramatically high porosity; this factor positively affects the reservoir properties of the rocks. After studying the secondary transformations of the sandy rocks, we have determined that the diagenesis stage is defined by the change of mineral composition. This alteration is mainly caused by organic material decomposition and the appearance of reducing environment. Considering the cover thickness, we have graded the transformations of the fragments of the sandy-aleuritic rocks of the depression. The pattern of the catagenetic changes at various depths has been introduced. In the end, we have inferred that the increasing depth starts influencing the three types of the structures, i.e. incorporating, reclaiming and microstilolite rather gradually. In addition, the declining importance of the conformal structures has been identified. The stress pattern of the catagenetically transformed solid rocks promotes the microfracture within the late catagenesis zones; this factor predetermines the development of decompression zones at the depths exceeding 4 km characterised by good reservoir properties.

scholarly journals Petrographical characteristics and post-depositional alteration affecting porosity and permeability of Oligocene sandstones, block 15-1/05, Cuu Long basin

2020 ◽  
Vol 4 (2) ◽  
pp. First
Author(s):  
Thanh Ngoc Do ◽  
Duyen Thi Pham ◽  
Phuong Kim Lieu
Keyword(s):  
Clay Minerals ◽  
Oil And Gas ◽  
Gas Storage ◽  
Early Diagenesis ◽  
Burial Depth ◽  
Reservoir Rocks ◽  
Potential Reservoir ◽  
Negative Effect ◽  
Porosity And Permeability ◽  
Grain Sorting

Petrographical characteristics and post-depositional alteration studies of sandstones are the two important factors to reservoir rocks, which affect oil and gas storage and permeability of reservoir rocks. This study revealed petrographical characteristics, post-depositional alteration, and their influence on the porosity and permeability of Oligocene sandstones, including C, D, and E and F sequences, block 15-1/05, Cuu Long Basin. The results show that most of the sandstones were arkose, lithic arkose, and sporadically interbedded by feldspathic greywacke. The post-depositional alteration was progressively increasing following the burial depth from early diagenesis of sequence C, to intermediate diagenesis of sequence D and advanced diagenesis of sequence E and F. The post-depositional alterations significantly influenced on the porosity of the Oligocene sandstone were the cementation and mechanical compaction. They reduced the porosity and permeability of the sandstone. Additionally, authigenic clay minerals have a negative effect on permeability in which sandstones were rich illite and illite-smectite clay minerals, and the permeability tended to decrease stronger than others. Our results showed that the potential reservoir rocks of Oligocene sandstones, block 15-1/05 were sequence E and F sandstones that are in well grain sorting, well grain roundness shape, and contained a small number of cement, particularly the absence of illite and illite-smectite.

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