scholarly journals Coupled experimental/numerical workflow for assessing quantitative diagenesis and dynamic porosity/permeability evolution in calcite-cemented sandstone reservoir rocks

2018 ◽  
Vol 73 ◽  
pp. 36 ◽  
Author(s):  
Steven Claes ◽  
Fadi H. Nader ◽  
Souhail Youssef
Keyword(s):  
Permeability Evolution ◽  
Flow Properties ◽  
New Approach ◽  
Reservoir Rocks ◽  
Pore Blocking ◽  
Diagenetic Processes ◽  
Porosity And Permeability ◽  
Sandstone Reservoir ◽  
Calcite Cement ◽  
Host Rocks

Some of the world best hydrocarbon reservoirs (carbonates and siliciclastics) are also believed to be valuable for subsurface storage of CO2 and other fluids. Yet, these reservoirs are heterogeneous in terms of their mineralogy and flow properties, at varying spatial-temporal scales. Therefore, predicting the porosity and permeability (flow properties) evolution of carbonates and sandstones remains a tedious task. Diagenesis refers to the alteration of sedimentary rocks through geologic time, mainly due to rock-fluid interactions. It affects primarily the flow properties (porosity and permeability) of already heterogeneous reservoir rocks. In this project a new approach is proposed to calculate/quantify the influence of diagenetic phases (e.g. dissolution, cement plugging) on flow properties of typical sandstone reservoir rocks (Early Jurassic Luxembourg Formation). A series of laboratory experiments are performed in which diagenetic phases (e.g. pore blocking calcite cement in sandstone) are selectively leached from pre-studied samples, with the quantification of the petrophysical characteristics with and without cement to especially infer permeability evolution. Poorly and heavily calcite-cemented sandstone samples, as well as some intermediate cemented samples were used. The results show a distinctive dissolution pattern for different cementation grades and varying Representative Elementary Volumes (REVs). These conclusions have important consequences for upscaling diagenesis effects on reservoirs, and the interpretation of geochemical modelling results of diagenetic processes. The same approach can be applied on other type of cements and host-rocks, and could be improved by integrating other petrophysical analyses (e.g. petroacoustic, NMR).

scholarly journals Generation of authigenic clay minerals during diagenesis and their influences on porosity and permeability of Oligocene sandstone reservoir rocks, from a well in the west of Cuu Long basin

2014 ◽  
Vol 17 (3) ◽  
pp. 21-26
Author(s):  
Toan Minh Ho ◽  
Phuong Kim Lieu ◽  
Thuy Thi Doan ◽  
Phuong Thi Ngoc Bui
Keyword(s):  
Clay Minerals ◽  
Fluid Flows ◽  
Reservoir Rock ◽  
Burial Depth ◽  
High Porosity ◽  
Pore Waters ◽  
The West ◽  
Reservoir Rocks ◽  
Porosity And Permeability ◽  
Sandstone Reservoir

Porosity and permeability play a prerequisite role for hydrocarbon reservoirs and fluid flows, especially in sandstone reservoir rocks. The rocks with high porosity decrease down to lower porosity with increasing burial depth due to compaction, cementation and precipitation of authigenic minerals in pores from over saturated solution of minerals. The detailed study of the authigenic clay mineral formation in pore spaces of sandstone reservoir rocks is therefore crucial to estimate the degree of reservoir rock quality. In this study 20 sandstone cores taken from the interval burial depths of 3,700 m - 4,200 m from Oligocene sandstone sequence of a well in the West of the Cuu Long basin, offshore Vietnam, were analyzed by SEM and thin section. Authigenic clay minerals were formed due to temperature and chemistry changes and owing to dissolution of less stable minerals in these burial depths. Authigenic chlorite mineral appears quite abundantly and illite is less frequently. Chlorite was formed from the elements Al and Si, which were released from dissolved grains and Fe and Mg supplied from breakdown of the ferromagnesian minerals of rock fragments and matrix components into pore waters in the burial stage. Illite is associated with the expense of grain dissolution of feldspar, volcanic fragment. Chlorite mostly appears as a coating or mats comprising of small pseudo-hexagonal crystals arranged perpendicular to detrital grain surfaces. Grainrimming chlorites on quartz grain are responsible for the preservation of the porosity in the sandstones because they limit the formation of quartz overgrowth. Additionally fibrous or flaky illite bridging the pores between the grains creates permeability barriers to fluid flows through the sandstones. Thus illite significantly reduces the permeability but to lesser extent affect porosity. Locally, smectite mixes with illite or chlorite and is not abundant in the studied samples. It therefore has no significant impact on the porosity and permeability as well. The variations of the porosity and the permeability of the studied sandstones depend on the generated degree and the arranged patterns of chlorite and illite in pore spaces.

Carbonate Diagenesis in a Sequence Stratigraphic Framework; Case study from Miocene Dam Formation, Eastern Saudi Arabia

2020 ◽  
Author(s):  
Moaz Salih ◽  
Osman Abdullatif ◽  
Khalid Al-Ramadan ◽  
Mazin Bashri
Keyword(s):  
Saudi Arabia ◽  
Arabian Plate ◽  
Sequence Stratigraphic ◽  
Hydrocarbon Reservoir ◽  
Diagenetic Processes ◽  
Porosity And Permeability ◽  
Thin Section Petrography ◽  
Calcite Cement ◽  
Sequence Boundaries ◽  
Analytical Tools

<p>The Miocene Dam Formation in the Al-Lidam area of Eastern Saudi Arabia consists of a succession </p><p>of mixed siliciclastic-carbonate sequences that were deposited during Miocene (Burdigalian) </p><p>times. Stratigraphic equivalents of the Dam Formation occur as hydrocarbon reservoir intervals in </p><p>the Arabian Plate. Reservoir quality of carbonate rocks is controlled by a combination of </p><p>depositional setting and post-depositional diagenetic factors. </p><p>In this study, fifteen lithofacies were identified as they were deposited on a low angle dipping </p><p>carbonate ramp, under supratidal, beach, intertidal and shallow subtidal conditions. Carbonate </p><p>diagenesis has been examined using: thin-section petrography, SEM, XRD and </p><p>cathodoluminescence. These analytical tools have shown that the intertidal lithofacies are </p><p>influenced by extensive meteoric dissolution and minor cementation. Marine diagenesis was </p><p>restricted to beach grainstone and subtidal lithofacies, in the form of aragonite and high magnesium </p><p>calcite cement. Shallow burial conditions were inferred by grain contacts represented by point, </p><p>suture and concavo-convex contacts. Mimetic dolomitization for the whole succession was also </p><p>observed. Three fourth - order, shallowing upward sequences were identified in the study area, and </p><p>they are separated by two sequence boundaries. A clear relation between sequence surfaces and </p><p>diagenetic processes was observed; meteoric diagenesis and dolomitization increases upwards in </p><p>each sequence. Porosity and permeability measurements have shown that the highest values are </p><p>associated with the HST of each sequence, followed by the TST and the LST. The results of this </p><p>study can help in understanding of diagenetic processes, and consequently in developing better </p><p>and more accurate predictions of the porosity and permeability distribution within hydrocarbon </p><p>reservoirs.</p><p> </p>

THE BASIC TYPES OF SECONDARY CHANGES IN RESERVOIR ROCKS IN THE TERRITORY OF THE WEST SIBERIA PLATE

2015 ◽  
pp. 26-30
Author(s):  
A. V. Podnebesnykh ◽  
S. V. Kuznetsov ◽  
V. P. Ovchinnikov
Keyword(s):  
Oil Recovery ◽  
West Siberia ◽  
Recovery Factor ◽  
Change Processes ◽  
The West ◽  
Reservoir Rocks ◽  
Tectonically Active ◽  
Porosity And Permeability ◽  
Active Zones ◽  
Regional Character

On the example of the group of fields in the West Siberia North the basic types of secondary changes in reservoir rocks are reviewed. Some of the most common types of such changes in the West Siberian plate territory include the processes of zeolitization, carbonation and leaching. These processes have, as a rule, a regional character of distribution and are confined to the tectonically active zones of the earth's crust. Due to formation of different mineral paragenesises the secondary processes differently affect the reservoir rocks porosity and permeability: thus, zeolitization and carbonization promote to reducing the porosity and permeability and leaching improvement. All this, ultimately leads to a change of the oil recovery factor and hydrocarbons production levels. Study and taking into account of the reservoir rocks secondary change processes can considerably influence on placement of operating well stock and on planning of geological and technological actions.

scholarly journals Multifractal Characteristics and Classification of Tight Sandstone Reservoirs: A Case Study from the Triassic Yanchang Formation, Ordos Basin, China

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2242 ◽  
Author(s):  
Zhihao Jiang ◽  
Zhiqiang Mao ◽  
Yujiang Shi ◽  
Daxing Wang
Keyword(s):  
Pore Structure ◽  
Ordos Basin ◽  
Type I ◽  
Tight Sandstone ◽  
Throat Radius ◽  
Yanchang Formation ◽  
Porosity And Permeability ◽  
Sandstone Reservoir ◽  
And Migration ◽  
Mercury Injection Capillary Pressure

Pore structure determines the ability of fluid storage and migration in rocks, expressed as porosity and permeability in the macroscopic aspects, and the pore throat radius in the microcosmic aspects. However, complex pore structure and strong heterogeneity make the accurate description of the tight sandstone reservoir of the Triassic Yanchang Formation, Ordos Basin, China still a problem. In this paper, mercury injection capillary pressure (MICP) parameters were applied to characterize the heterogeneity of pore structure, and three types of pore structure were divided, from high to low quality and defined as Type I, Type II and Type III, separately. Then, the multifractal analysis based on the MICP data was conducted to investigate the heterogeneity of the tight sandstone reservoir. The relationships among physical properties, MICP parameters and a series of multifractal parameters have been detailed analyzed. The results showed that four multifractal parameters, singularity exponent parameter (αmin), generalized dimension parameter (Dmax), information dimension (D1), and correlation dimension (D2) were in good correlations with the porosity and permeability, which can well characterize the pore structure and reservoir heterogeneity of the study area, while the others didn’t respond well. Meanwhile, there also were good relationships between these multifractal and MICP parameters.

scholarly journals Induced microearthquakes predict permeability creation in the brittle crust

2022 ◽  
Author(s):  
Ziyan Li ◽  
Derek Elsworth ◽  
Chaoyi Wang
Keyword(s):  
Patch Size ◽  
Dynamic Evolution ◽  
Permeability Evolution ◽  
Field Scale ◽  
Scale Invariant ◽  
Flow Paths ◽  
Porosity And Permeability ◽  
Hybrid Machine ◽  
Early Injection

Abstract Fracturing controls rates of mass, chemical and energy cycling within the crust. We use observed locations and magnitudes of microearthquakes (MEQs) to illuminate the evolving architecture of fractures reactivated and created in the otherwise opaque subsurface. We quantitatively link seismic moments of laboratory MEQs to the creation of porosity and permeability at field scale. MEQ magnitudes scale to the slipping patch size of remanent fractures reactivated in shear - with scale-invariant roughnesses defining permeability evolution across nine decades of spatial volumes – from centimeter to decameter scale. This physics-inspired seismicity-permeability linkage enables hybrid machine learning (ML) to constrain in-situ permeability evolution at verifiable field-scales (~10 m). The ML model is trained on early injection and MEQ data to predict the dynamic evolution of permeability from MEQ magnitudes and locations, alone. The resulting permeability maps define and quantify flow paths verified against ground truths of permeability.

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