Geophysical evaluation of sandstone aquifers in the Recôncavo‐Tucano Basin, Bahia—Brazil

Geophysics ◽  
1993 ◽  
Vol 58 (11) ◽  
pp. 1689-1702 ◽  
Author(s):  
Olivar A. L. de Lima
Keyword(s):  
Laboratory Data ◽  
Flood Plain ◽  
Hydrodynamic Dispersion ◽  
Formation Factor ◽  
Water Leakage ◽  
Geothermal Waters ◽  
Aquifer System ◽  
Resistivity Logs ◽  
Porosity And Permeability ◽  
Water Resistivity

The upper clastic sediments in the Recôncavo‐Tucano basin comprise a multilayer aquifer system of Jurassic age. Its groundwater is normally fresh down to depths of more than 1000 m. Locally, however, there are zones producing high salinity or sulfur geothermal waters. In other areas, the system is being exploited heavily to support a petrochemical center and related industries. Analysis of electrical logs of more than 150 wells enabled the identification of the most typical sedimentary structures and the gross geometries for the sandstone units in selected areas of the basin. Based on this information, the thick sands are interpreted as coalescent point bars and the shales as flood plain deposits of a large fluvial environment. The resistivity logs and core laboratory data are combined to develop empirical equations relating aquifer porosity and permeability to log‐derived parameters such as formation factor and cementation exponent. Temperature logs of 15 wells were useful to quantify the water leakage through semiconfining shales. The groundwater quality was inferred from spontaneous potential (SP) log deflections under control of chemical analysis of water samples. An empirical chart is developed that relates the SP‐derived water resistivity to the true water resistivity within the formations. The patterns of salinity variation with depth inferred from SP logs were helpful in identifying subsurface flows along major fault zones, where extensive mixing of water is taking place. A total of 49 vertical Schlumberger resistivity soundings aid in defining aquifer structures and in extrapolating the log derived results. Transition zones between fresh and saline waters have also been detected based on a combination of logging and surface sounding data. Ionic filtering by water leakage across regional shales, local convection and mixing along major faults and hydrodynamic dispersion away from lateral permeability contrasts are the main mechanisms controlling the observed distributions of salinity and temperature within the basin.

Spatial Variation of Aquifer Parameters from Coastal Aquifers of Sindhudurg District, Maharashtra Using Pore-water Resistivity and Bulk Resistivity

2018 ◽  
Vol 1 (1) ◽  
pp. 28-40
Author(s):  
Suneetha Naidu ◽  
Gautam Gupta
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Coastal Aquifers ◽  
Hydraulic Parameters ◽  
Formation Factor ◽  
Bulk Resistivity ◽  
Good Correspondence ◽  
Aquifer System ◽  
Transverse Resistance ◽  
Water Resistivity

Estimation of hydraulic parameters in coastal aquifers is an important task in groundwater resource assessment and development. An attempt is made to estimate these parameters using geoelectrical data in combination with pore-water resistivity of existing wells. In the present study, 29 resistivity soundings were analysed along with 29 water samples, collected from the respective dug wells and boreholes, in order to compute hydraulic parameters like formation factor, porosity, hydraulic conductivity and transmissivity from coastal region of north Sindhudurg district, Maharashtra, India. The result shows some parts of the study area reveal relatively high value of hydraulic conductivity, porosity and transmissivity. Further, a negative correlation is seen between hydraulic conductivity and bulk resistivity. The hydraulic conductivity is found to vary between 0.014 and 293 m/day, and the transmissivity varied between 0.14 and 11,722 m2/day. The transmissivity values observed here are in good correspondence with those obtained from pumping test data of Central Ground Water Board. These zones also have high aquifer thickness and therefore characterize high potential within the water-bearing formation. A linear, positive relationship between transverse resistance and transmissivity is observed, suggesting increase in transverse resistance values indicate high transmissivity of aquifers. These relations will be extremely vital in characterization of aquifer system, especially from crystalline hard rock area.

scholarly journals SAPHYR: Swiss Atlas of Physical Properties of Rocks: the continental crust in a database

2021 ◽  
Vol 114 (1) ◽  
Author(s):  
Alba Zappone ◽  
Eduard Kissling
Keyword(s):  
Physical Properties ◽  
Laboratory Data ◽  
Rock Physics ◽  
Resource Planning ◽  
Data Representation ◽  
Common People ◽  
Rock Types ◽  
Gis Tools ◽  
Porosity And Permeability ◽  
Thermal And Electrical Properties

AbstractThe Swiss Atlas of Physical Properties of Rocks (SAPHYR) project aims at centralize, uniform, and digitize dispersed and often hardly accessible laboratory data on physical properties of rocks from Switzerland and surrounding regions. The goal of SAPHYR is to make the quality-controlled and homogenized data digitally accessible to an open public, including industrial, engineering, land and resource planning companies as well as governmental and academic institutions, or simply common people interested in rock physics. The physical properties, derived from pre-existing literature or newly measured, are density, porosity and permeability as well as seismic, magnetic, thermal and electrical properties. The data were collected on samples either from outcrops or from tunnels and boreholes. At present, data from literature have been collected extensively for density, porosity, seismic and thermal properties. In the past years, effort has been placed especially on collecting samples and measuring the physical properties of rock types that were poorly documented in literature. A workflow for quality control on reliability and completeness of the data was established. We made the attempt to quantify the variability and the uncertainty of the data. The database has been recently transferred to the Federal Office of Topography swisstopo with the aim to develop the necessary tools to query the database and open it to the public. Laboratory measurements are continuously collected, therefore the database is ongoing and in continuous development. The spatial distribution of the physical properties can be visualized as maps using simple GIS tools. Here the distribution of bulk density and velocity at room conditions are presented as examples of data representation; the methodology to produce these maps is described in detail. Moreover we also present an exemplification of the use of specific datasets, for which pressure and temperatures derivatives are available, to develop crustal models.

scholarly journals Petrophysical Properties of Nahr Umar Formation in Nasiriya Oil Field

2020 ◽  
Vol 21 (3) ◽  
pp. 9-18
Author(s):  
Ahmed Abdulwahhab Suhail ◽  
Mohammed H. Hafiz ◽  
Fadhil S. Kadhim
Keyword(s):  
Gamma Ray ◽  
Water Saturation ◽  
Oil Field ◽  
Well Logs ◽  
High Porosity ◽  
Reservoir Properties ◽  
Petrophysical Parameters ◽  
Resistivity Logs ◽  
Lithology Prediction ◽  
Porosity And Permeability

   Petrophysical characterization is the most important stage in reservoir management. The main purpose of this study is to evaluate reservoir properties and lithological identification of Nahr Umar Formation in Nasiriya oil field. The available well logs are (sonic, density, neutron, gamma-ray, SP, and resistivity logs). The petrophysical parameters such as the volume of clay, porosity, permeability, water saturation, were computed and interpreted using IP4.4 software. The lithology prediction of Nahr Umar formation was carried out by sonic -density cross plot technique. Nahr Umar Formation was divided into five units based on well logs interpretation and petrophysical Analysis: Nu-1 to Nu-5. The formation lithology is mainly composed of sandstone interlaminated with shale according to the interpretation of density, sonic, and gamma-ray logs. Interpretation of formation lithology and petrophysical parameters shows that Nu-1 is characterized by low shale content with high porosity and low water saturation whereas Nu-2 and Nu-4 consist mainly of high laminated shale with low porosity and permeability. Nu-3 is high porosity and water saturation and Nu-5 consists mainly of limestone layer that represents the water zone.

Petrophysical inversion of borehole array-induction logs: Part II — Field data examples

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. G261-G268 ◽  
Author(s):  
Carlos Torres-Verdín ◽  
Faruk O. Alpak ◽  
Tarek M. Habashy
Keyword(s):  
Electromagnetic Induction ◽  
Layer By Layer ◽  
Laboratory Measurements ◽  
Inversion Algorithm ◽  
Vertical Wells ◽  
Gas Field ◽  
Rock Formations ◽  
Resistivity Logs ◽  
Porosity And Permeability ◽  
Induction Logs

We describe the application of Alpak et al.’s (2006) petrophysical inversion algorithm to the interpretation of borehole array induction logs acquired in an active North American gas field. Layer-by-layer values of porosity and permeability were estimated in two closely spaced vertical wells that penetrated the same horizontal rock formation. The wells were drilled with different muds and overbalance pressures, and the corresponding electromagnetic induction logs were acquired with different tools. Rock-core laboratory measurements available in one of the two wells were used to constrain the efficiency of gas displacement by water-based mud during the process of invasion. Estimated values of porosity and permeability agree well with measurements performed on rock-core samples. In addition to estimating porosity and permeability, the petrophysical inversion algorithm provided accurate spatial distributions of gas saturation in the invaded rock formations that were not possible to obtain with conventional procedures based solely on the use of density and resistivity logs.

Estimating porosity and permeability in the Springbok Sandstone, Surat Basin (Queensland), using new wireline log-based workflow

2021 ◽  
Vol 61 (2) ◽  
pp. 720
Author(s):  
Kasia Sobczak ◽  
Heinz-Gerd Holl ◽  
Andrew Garnett
Keyword(s):  
Upper Jurassic ◽  
Coal Seams ◽  
Impact Prediction ◽  
Reservoir Models ◽  
Resistivity Logs ◽  
Porosity And Permeability ◽  
Sandstone Formation ◽  
Definition Of ◽  
Coal Measures

The Upper Jurassic Walloon Coal Measures of the Surat Basin (Queensland) host some of the most prominent coal seam gas (CSG) resources in Australia. The Walloon Coal Measures are directly overlain by the Springbok Sandstone formation, historically referred to as a regional aquifer. An increasing number of studies and industry models suggest relatively limited hydraulic connectivity within the formation and between it and the underlying coal measures, due to extreme lithological heterogeneity. Accurate evaluation of the permeability, as well as lateral and vertical continuity of the lithological units within the Springbok Sandstone, is critical in reservoir models that form the basis of reasonable aquifer protection practices and impact prediction. This study presents a wireline log-based workflow applied to identify permeable zones within the Springbok Sandstone in 31 CSG wells across the Surat Basin that allows robust estimations of porosities and Klinkenberg permeabilities. The workflow primarily utilises spontaneous potential, density, neutron and resistivity logs, and was developed by integrating current industry practices implemented by operators on a local scale to identify risk (permeable) zones in the vicinity of targeted coal seams. The results of this case study indicate that permeable zones within the interval are volumetrically minor (on average 25% N/G) and likely isolated, with Klinkenberg permeabilities rarely exceeding 10–20mD. This evidence for low hydraulic connectivity, as well as significant local variations in the character of the Springbok Sandstone, suggests that the definition of the formation as a regional, continuous aquifer and the way it is modelled needs to be revised.

scholarly journals Characterization of the Carbonate Formation Fracture System Based on Well Logging Data and Results of Laboratory Measurements

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6034
Author(s):  
Marek Stadtműller ◽  
Paulina I. Krakowska-Madejska ◽  
Grzegorz Leśniak ◽  
Jadwiga A. Jarzyna
Keyword(s):  
Computed Tomography ◽  
Carbonate Rock ◽  
Laboratory Data ◽  
Well Logging ◽  
Polished Section ◽  
Fracture System ◽  
Micro Computed Tomography ◽  
Carbonate Formation ◽  
Porosity And Permeability ◽  
Dolomite Formation

This article presents a novel methodology for data integration including laboratory data, the results of standard well logging measurements and interpretation and the interpretation of XRMI imager data for determination of the porosity and permeability of the fracture system in carbonate rock. An example of the results of the micro computed tomography applied for carbonate rock is included. Data were obtained on the area of the Polish Lowland Zechstein Main Dolomite formation. The input set of data included the results of mercury injection porosimetry (MICP), thin section and polished section analysis, well logging measurements and comprehensive interpretation and micro computed tomography. The methodology of the macrofractures’ analysis based on borehole wall imagery as well as estimation of their aperture was described in detail. The petrophysical characteristics of the fracture systems were analyzed as an element of standard interpretation of well logging data along a carbonate formation. The results of permeability determination, with micro-, mezzo- and macrofractures’ presence in the rock taken into consideration, were compared with outcomes of the drill stem tests (DSTs).

scholarly journals Pumping test analysis for assessment of hydraulic parameters and aquifer system formation in hilly terrain

2022 ◽  
Author(s):  
Sonu Singh ◽  
Joseph Tripura
Keyword(s):  
Pumping Test ◽  
Hydraulic Parameters ◽  
Well Performance ◽  
Hilly Terrain ◽  
Test Analysis ◽  
Aquifer System ◽  
System Formation ◽  
Porosity And Permeability ◽  
Comparative Results

Abstract Groundwater conditions (GWCs) of an area depends on aquifer hydraulic parameters such as storativity () or storage coefficient (), transmissivity () and hydraulic conductivity (). It plays a key role concerning- groundwater flow modeling, well performance, solute and contaminants transports assessment and also for identification of areas for additional hydrologic testing. Specifically, the geologic formation of a regions control the porosity and permeability, however, in hilly terrain prospecting ground water potential is more challenging due to its limited extent and its occurrences that are usually confined to fractures and weathered rocks. The present study, aims at estimating the hydraulic parameters through pumping test analysis to assess aquifer system formation on hilly terrain from 16 bore wells. The aforesaid parameters were examined through a case study in some selective regions of Hamirpur district of Himachal Pradesh, India. The study area is controlled under two main geological horizons that is the post-tertiary and tertiary. The papers end with comparative results of hydraulic parameters and the aquifers system formation on different GWCs which may be helpful in the outlook of sustainable groundwater resource in the regions.

Upscaling laboratory measurements: Quantifying the role of hydrothermal alteration in creating geothermal and epithermal mineral resources

2020 ◽  
Author(s):  
Michael Heap ◽  
Darren Gravley ◽  
Ben Kennedy ◽  
Albert Gilg ◽  
Elisabeth Bertolett ◽  
...  
Keyword(s):  
Rock Mass ◽  
Hydrothermal Alteration ◽  
Hydrothermal System ◽  
Geothermal Energy ◽  
Laboratory Data ◽  
Mineral Resources ◽  
Low Permeability ◽  
Fluid Circulation ◽  
Porosity And Permeability

<p>Hydrothermal fluids can alter the chemical and physical properties of the materials through which they pass and can therefore modify the efficiency of fluid circulation. The role of hydrothermal alteration in the development of geothermal and epithermal mineral resources, systems that require the efficient hydrothermal circulation provided by fracture networks, is investigated here from a petrophysical standpoint using samples collected from a well exposed and variably altered palaeo-hydrothermal system hosted in the Ohakuri ignimbrite deposit in the Taupō Volcanic Zone (New Zealand). Our new laboratory data show that, although quartz and adularia precipitation reduces matrix porosity and permeability, it increases the uniaxial compressive strength, Young’s modulus, and propensity for brittle behaviour. The fractures formed in highly altered rocks containing quartz and adularia are also more planar than those formed in their less altered counterparts. All of these factors combine to enhance the likelihood that a silicified rock-mass will host permeability-enhancing fractures. Indeed, the highly altered silicified rocks of the Ohakuri ignimbrite deposit are much more fractured than less altered outcrops. By contrast, smectite alteration at the margins of the hydrothermal system does not significantly increase strength or Young’s modulus, or significantly decrease permeability, and creates a relatively unfractured rock-mass. Using our new laboratory data, we provide permeability modelling that shows that the equivalent permeability of a silicified rock-mass will be higher than that of a less altered rock-mass or a rock-mass characterised by smectite alteration, the latter of which provides a low-permeability cap required for an economically viable hydrothermal resource. Our new data show, using a petrophysical approach, how hydrothermal alteration can produce rock-masses that are both suitable for geothermal energy exploitation (high-permeability reservoir and low-permeability cap) and more likely to host high-grade epithermal mineral veins, such as gold and silver (localised fluid flow).</p>

Reservoir facies mapping, depositional environment, and implication for hydrocarbon occurrence: A case study from Ariyalur-Pondicherry subbasin, Cauvery Basin, India

2020 ◽  
Vol 39 (12) ◽  
pp. 909-917
Author(s):  
Sushmita S. Sengupta ◽  
Jyoti Singh ◽  
Ravi Prakash ◽  
Harilal
Keyword(s):  
Reservoir Characterization ◽  
Channel Model ◽  
Laboratory Data ◽  
Coarse Grained ◽  
Integrated Analysis ◽  
Root Mean Square Amplitude ◽  
Gaseous Hydrocarbon ◽  
Clay Coating ◽  
Porosity And Permeability ◽  
Reservoir Facies

Commercial gaseous hydrocarbon has been established from multilayered reservoirs within the Bhuvanagiri Formation in the Ariyalur-Pondicherry subbasin, but sustained production is obtained from only a few wells of the Bhuvanagiri Field. This has necessitated developing an integrated depositional model dovetailing distribution of favorable reservoir areas of the Bhuvanagiri Formation within the subbasin. Root-mean-square amplitude attributes and spectral decomposition attributes, along with RGB blending of spectral slices at different frequencies, have revealed a conspicuously northeast-southwest-trending channel within the Bhuvanagiri Formation. From well, sedimentological, and biostratigraphic data analysis, a deepwater turbidity channel model for the Bhuvanagiri Formation has been postulated. Deciphering the facies distribution pattern vertically and laterally within the turbidity channel is often complex and challenging. Integrated analysis of available laboratory data, petrographic, and scanning electron microscopy studies indicate poor porosity and permeability because of clay coating on grains, occurrence of authigenic clay as pore fill, cementation, and other diagenetic changes that have made reservoir characterization increasingly challenging. Four major lithofacies assemblages have been identified: basal lags, slumps and debris flows, arenaceous coarse-grained stacked channels, and fine-grained channel levee with characteristic log and seismic responses. To characterize the lithofacies, various crossplots have been generated by using processed logs to derive interrelationships between reservoir facies and log impedance. A model-based inversion has been attempted, which resulted in fairly satisfactory output with likely discrimination of reservoir and nonreservoir in an unexplored area within the field. The outcome would facilitate further exploration and delineation activities within the Bhuvanagiri Formation in the Ariyalur-Pondicherry subbasin.

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