Sand injectite mapping using a resistivity-velocity transform function

2021 ◽  
Vol 40 (3) ◽  
pp. 202-207
Author(s):  
Anke S. Wendt ◽  
Monzurul Alam ◽  
Joao Paulo Castagnoli
Keyword(s):  
Residual Velocity ◽  
Rock Types ◽  
Geostatistical Approach ◽  
Spatially Distributed ◽  
Resistivity Logs ◽  
Hydrocarbon Fields ◽  
Interval Velocities ◽  
Resistivity Log ◽  
Measured Resistivity ◽  
Sand Bodies

Lack of resolution in the distribution of sand injectites in hydrocarbon fields is common and makes it difficult to predict drilling challenges and plan for optimum production. A practical workflow was developed that enables the distinction of shale and sand bodies by using a combination of low-resolution seismic data and high-resolution resistivity log data. Measured resistivity logs were used to predict synthetic velocity logs, which accurately match shale velocities and over- or underestimate velocities of other rock types. The synthetic velocity logs were spatially distributed in a 3D cube in order to predict synthetic velocities in between and away from the well locations. The 3D cube was representative of a field. It covered the interval from the seabed to below the reservoir. The spatial distribution was based on a geostatistical approach guided by measured seismic interval velocities. A residual velocity cube was calculated from the measured and synthetic velocities. The residual velocity cube produced near-zero velocities for shaly materials and velocity over- or underestimates for other rock types. Interpretation of the residual velocity cube required the identification of strong stratigraphic markers. The markers were removed from the residual cube by setting their specific layer velocities to 0 m/s. The final information stored in the residual velocity cube was then related to the over- or underestimated velocities in sand bodies.

scholarly journals Evaluation of Petrophysical Parameters of Reservoir Sand Wells in Uzot-Field, Onshore Niger Delta Basin, Nigeria

2021 ◽  
Vol 25 (2) ◽  
pp. 157-171
Author(s):  
UC Omoja ◽  
T.N. Obiekezie
Keyword(s):  
Niger Delta ◽  
Gamma Ray ◽  
Depth Range ◽  
High Hydrocarbon ◽  
Hydrocarbon Production ◽  
Petrophysical Parameters ◽  
Resistivity Logs ◽  
Hydrocarbon Saturation ◽  
Niger Delta Basin ◽  
Sand Bodies

Evaluation of the petrophysical parameters in Uzot-field was carried out using Well log data. The target for this study was the D3100 reservoir sand of wells Uz 004, Uz 005, U008 and Uz 011 with depth range of 5540ft to 5800ft across the four wells. Resistivity logs were used to identify hydrocarbon or water-bearing zones and hence indicate permeable zones while the various sand bodies were then identified using the gamma ray logs. The results showed the delineated reservoir units having porosity ranging from 21.40% to 33.80% indicating a suitable reservoir quality; permeability values from 1314md to 18089md attributed to the well sorted nature of the sands and hydrocarbon saturation range from 12.00% to 85.79% implying high hydrocarbon production. These results suggest a reservoir system whose performance is considered satisfactory for hydrocarbon production. Keywords: Petrophysical parameters, porosity, permeability, hydrocarbon saturation, Niger Delta Basin

Rock typing and facies identification using fractal theory and conventional petrophysical logs

2018 ◽  
Vol 58 (1) ◽  
pp. 102
Author(s):  
Roozbeh Koochak ◽  
Manouchehr Haghighi ◽  
Mohammad Sayyafzadeh ◽  
Mark Bunch
Keyword(s):  
Fractal Dimension ◽  
Multiple Scales ◽  
Fractal Theory ◽  
Depositional Environments ◽  
Log Data ◽  
Rock Types ◽  
Rock Typing ◽  
Resistivity Logs ◽  
Shaly Sand ◽  
Rock Texture

Rock typing or subdivision of a reservoir either vertically or laterally is an important task in reservoir characterisation and production prediction. Different depositional environments and diagenetic effects create rocks with different grain size distribution and grain sorting. Rock typing and zonation is usually made by analysing log data and core data (mercury injection capillary pressure and permeability measurement). In this paper, we introduce a new technique (approach) for rock typing using fractal theory in which resistivity logs are the only required data. Since resistivity logs are sensitive to rock texture, in this study, deep conventional resistivity logs are used from eight different wells. Fractal theory is applied to our log data to seek any meaningful relationship between the variability of resistivity logs and complexity of rock fabric. Fractal theory has been previously used in many stochastic processes which have common features on multiple scales. The fractal property of a system is usually characterised by a fractal dimension. Therefore, the fractal dimension of all the resistivity logs is obtained. The results of our case studies in the Cooper Basin of Australia show that the fractal dimension of resistivity logs increases from 1.14 to 1.29 for clean to shaly sand respectively, indicating that the fractal dimension increases with complexity of rock texture. The fractal dimension of resistivity logs is indicative of the complexity of pore fabric, and therefore can be used to define rock types.

scholarly journals Petrophysical Analysis of ‘Bright’ Field, Onshore Niger Delta

2021 ◽  
Keyword(s):  
Niger Delta ◽  
Gamma Ray ◽  
Water Saturation ◽  
Research Work ◽  
Accurate Estimation ◽  
Bright Field ◽  
Petrophysical Analysis ◽  
Lithology Identification ◽  
Resistivity Logs ◽  
Sand Bodies

Petrophysical analysis is key to the success of any oil exploration and exploitation work and this task requires evaluation of the reservoir parameters in order to enhance accurate estimation of the volume of oil in place. This research work involves the use of suite of well logs from 4-wells to carry out the petrophysical analysis of ‘Bright’ Field Niger Delta. The approach used includes lithology identification, reservoir delineation and estimation of reservoir parameters. Two sand bodies were mapped across the entire field showing their geometry and lateral continuity, gamma ray and resistivity logs were used to delineate the reservoirs prior to correlation and relevant equations were used to estimate the reservoir parameters. The result of the petrophysical analysis showed variations in the reservoir parameters within the two correlated sand bodies with high hydrocabon saturation in sand 1 well 1 while the remaining wells within the correlated wells are water bearing. The porosity values range from 0.19 to 0.32, volume of shale from 0.15 to 0.40, water saturation from 0.20 to 0.92 for the sand bodies.

THE USE OF THERMAL RESISTIVITY LOGS IN STRATIGRAPHIC CORRELATION

Geophysics ◽  
1976 ◽  
Vol 41 (2) ◽  
pp. 300-309 ◽  
Author(s):  
A. E. Beck
Keyword(s):  
Electrical Resistivity ◽  
Temperature Gradients ◽  
Thermal Resistivity ◽  
Stratigraphic Correlation ◽  
Resistivity Logs ◽  
Precision Temperature ◽  
Order Of Magnitude ◽  
The Mean ◽  
Resistivity Log ◽  
Gas Bearing

Since it has been found that the heat flow along a borehole rarely deviates more than 20 percent from the mean equilibrium value and that formation thermal resistivities may vary by as much as an order of magnitude, the profile of temperature gradient versus depth is equivalent to a log of thermal resistivity (T-log). In this work high precision temperature measurements in cased boreholes were used which yielded temperature gradients as high as 140°C/km. Using the equivalence between thermal resistivity and temperature gradients, it has been found that the T-logs are characteristic of the formations in which they were measured with a general negative correlation between thermal resistivity and electrical resistivity, except in coal (and perhaps gas) bearing formations. In one instance, the character of the resistivity log was used to conclude that a horizon deduced from the electrical resistivity log had been mispicked by nearly 100 m.

Well‐logging method

Geophysics ◽  
1980 ◽  
Vol 45 (11) ◽  
pp. 1667-1684 ◽  
Author(s):  
F. F. Segesman
Keyword(s):  
Gamma Ray ◽  
Neutron Density ◽  
Accurate Analysis ◽  
Resistivity Logs ◽  
Computer Input ◽  
The 1960S ◽  
Log Interpretation ◽  
Resistivity Log ◽  
Self Potential ◽  
Continuous Temperature

By 1930, the resistivity log was recorded commercially in several countries, and in 1931 the self‐potential (SP) measurement was added. An electromagnetic (EM) teleclinometer was introduced in 1932, a continuous temperature log in 1933, and an anisotropy dipmeter ca. 1935. The significance of the SP was an ongoing study until about 1962. The bases for the quantitative interpretation of resistivity for saturation were formulated by 1941. The years from about 1940 into the 1960s saw the development of other basic logs—dipmeter, gamma ray, neutron, induction, microresistivity, focused resistivity, density, and acoustic velocity—as well as other miscellaneous logs. Suites of resistivity logs were evolved to provide more accurate analysis. Much effort was expended on the interpretation of shaly sands. Neutron, density, and acoustic logs yielded information on porosity, lithology, gas saturation, and/or shaliness. Availability of porosity from these logs facilitated resistivity‐log interpretation. In the late 1950s, interest developed in the use of computers for log interpretation. By about 1961, dipmeter logs were being recorded on digital magnetic tape suitable for computer input, and other logs were available by about 1965. Digital recording has also facilitated transmission of logs via radio and telephone. Recently, digital systems for wellsite computations have been introduced.

Interpretation of hydraulic rock types with resistivity logs in Tertiary deepwater turbidite reservoirs: Pore-scale modeling verified with field observations in the Gulf of Mexico, USA

2013 ◽  
Vol 1 (2) ◽  
pp. T177-T185 ◽  
Author(s):  
Chicheng Xu ◽  
Carlos Torres-Verdín ◽  
Shuang Gao
Keyword(s):  
Hydraulic Conductivity ◽  
Gulf Of Mexico ◽  
Pore Size ◽  
Water Saturation ◽  
Size Distributions ◽  
Clastic Rocks ◽  
Rock Types ◽  
Rock Typing ◽  
Irreducible Water Saturation ◽  
Resistivity Logs

Well-log-based hydraulic rock typing is critical in deepwater reservoir description and modeling. Resistivity logs are often used for hydraulic rock typing due to their high sensitivity to rock textural attributes such as porosity and tortuosity. However, resistivity logs measured at different water saturation conditions need to be cautiously used for hydraulic rock typing because, by definition, the properties of hydraulic rock types (HRT) are independent of fluid saturation. We compare theoretical models of electrical and hydraulic conductivity of clastic rocks exhibiting different pore-size distributions and originating from different sedimentary grain sizes. When rocks exhibiting similar porosity ranges are fully saturated with high-salinity water, hydraulic conductivity is dominantly controlled by characteristic pore size while electrical conductivity is only marginally affected by the characteristic pore size. As a result, rock types with similar porosity but different characteristic pore sizes cannot be effectively differentiated with resistivity logs in a water-bearing zone. In a hydrocarbon-bearing zone at irreducible water saturation, capillary pressure gives rise to specific desaturation behaviors in different rock types during hydrocarbon migration, thereby causing differentiable resistivity log attributes that are suitable for classifying HRT. Core data and well logs acquired from a deep-drilling exploration well penetrating Tertiary turbidite oil reservoirs in the Gulf of Mexico, verify that inclusion of resistivity logs in the rock classification workflow can significantly improve the accuracy of hydraulic rock typing in zones at irreducible water saturation. Classification results exhibit a good agreement with those obtained from nuclear magnetic resonance logs, but have relatively lower vertical resolution. The detected and ranked HRT exhibit different grain-size distributions, which provide useful information for sedimentary facies analysis.

scholarly journals Photogrammetric mapping of fluvial channel sand-bodies in the Atane Formation at Paatuut, Nuussuaq, central West Greenland

1992 ◽  
Vol 156 ◽  
pp. 41-46
Author(s):  
T Olsen
Keyword(s):  
Cross Sections ◽  
Large Scale ◽  
Upper Cretaceous ◽  
Three Dimensional ◽  
Thickness Ratio ◽  
South Coast ◽  
Sand Body ◽  
Hydrocarbon Fields ◽  
Reservoir Geometry ◽  
Sand Bodies

Upper Cretaceous deltaic sediments from the Atane Formation are well exposed in a series of steep-sided gullies at Paatuut on the south coast of Nuussuaq. The large exposures within the gullies allowed a large-scale sedimentological investigation of delta stratigraphy, sand-body geometry and fluvial style of the distributary channels. Multi-model photogrammetry was applied in several ways. Photogrammetric mapping of good exposures within the area produced accurate vertical sections up to 2 km long and 0.5 km high. A bed to bed stratigraphy of the delta cycles was established and the sand-bodies within each cycle correlated. The horizontal extent of the sand-bodies was subsequently mapped photogrammetrically using the already orientated stereomodels. This mapping allowed a three-dimensional interpretation of the sand-body geometry. Cross-sections of the sand-bodies and the sand-body geometry formed the basis for the interpretation of the fluvial style of the distributary channels. Using the three-dimensional photogrammetric data the width/thickness ratio, the sinuosity and the shape of sand-bodies as well as of palaeochannels are described. These data are useful when modelling the reservoir geometry in deltaic hydrocarbon fields.

scholarly journals Analysis of the relationship between porosity and permeability in reservoir modeling using the petrophysical rock type approach

2020 ◽  
Vol 1 (1) ◽  
pp. 48-55
Author(s):  
Lena Maretha Salindeho
Keyword(s):  
Gamma Ray ◽  
Water Saturation ◽  
Rock Type ◽  
Carbonate Reservoir ◽  
Reservoir Modeling ◽  
Hydrocarbon Production ◽  
Rock Types ◽  
Porosity And Permeability ◽  
Hydrocarbon Fields ◽  
Reef Platform

The carbonate reservoir is one of the reservoir characters found in hydrocarbon fields in Indonesia. Carbonate reservoirs have complex porosity and permeability relationships. So it is necessary to do a special reservoir character that is different from the siliciclastic reservoir. Efforts that can be made to assist the development of this hydrocarbon field are to analyze the reservoir character in more detail using the petrophysical rock type (PRT) approach. This approach is used by combining geological elements such as the depositional environment, the petrophysical properties of the rock, as well as the fluid flow in it which is reflected by capillary pressure and water saturation. Modeling with this method is expected to be a method that can increase hydrocarbon production optimally in Xena Field. The object of research from Xena Field is Zone A2 which is included in the Parigi Formation. The Parigi Formation is one of the main hydrocarbon-producing reservoirs. The data used in this study are routine core analysis (RCAL) rock data on JLB-07, JLB-08, JLB-02, JLB-23 wells, wire log data (gamma-ray log, resistivity log, density log, neutron log) of 30 wells, and 2D seismic data. The depositional facies are divided into 2 facies, namely the margin reef platform facies and the interior platform facies. Identification of rock type (RT) using the flow zone indicator (FZI) method. The rock type in this field can be divided into 4 rock types, namely RT 1, RT 2, RT 3, RT 4 with RT 1 being able to drain the best fluid and RT 4 to drain the worst fluid. Reservoir property modeling is controlled by facies and rock type (RT) models. The margin reef platform facies are associated with RT 1 and RT 2. The interior platform facies are associated with RT 2 and RT 3.

scholarly journals Interpretation of 1D-Resistivity Data to Describe the Aquifer Model in the Serayu Watershed Area of Somagede Village, Somagede District, Banyumas Regency

2021 ◽  
Vol 22 (2) ◽  
pp. 89
Author(s):  
Sehah Sehah ◽  
Hartono Hartono ◽  
Zaroh Irayani ◽  
Urip Nurwijayanto Prabowo ◽  
Fajar Apriyanto ◽  
...  
Keyword(s):  
Research Area ◽  
Watershed Area ◽  
Research Results ◽  
Resistivity Data ◽  
Deep Aquifers ◽  
Gravel Layer ◽  
Sandy Clay ◽  
Groundwater Aquifer ◽  
Resistivity Logs ◽  
Resistivity Log

Acquisition of resistivity data using the Schlumberger configuration has been carried out in the Serayu watershed area of Somagede Village, Somagede District, Banyumas Regency. The purpose of this research was to describe a groundwater aquifer model based on the interpretation of 1D-resistivity data. The research results are resistivity logs of subsurface rock distributed over seven sounding points with resistivity values ranging from 2.24-192.78 m. The sounding points are located at positions of 7°31′28.55″ and 109°19′8.65″ (Sch-1) to 7°31′18.79″ and 109°19′21.45″ (Sch-7). The interpretation of the resistivity logs has resulted in a lithology log at each sounding point. Based on the interpretation, the lithology of the research area is composed of topsoil (42.85-85.13 m), sandy clay which partly slightly wet (7.08-17.18m), sandy clay inserted with gravel (22.44-31.70 m), sand, gravel, and pebble, with various consolidated (22.16-192.78m), sand inserted by gravel (6.77m), alternating sandstone and claystone, some of which are alternated with marl and tuff (8.71-21.99m), and sandstones with various porosity (3.25-8.76m). Shallow aquifers are interpreted to exist in sand inserted by gravel layer (13.23-27.67 m) at the sounding point of Sch-2 where the potential is quite good. While deep aquifers are estimated to be present in the sandstone layer with various porosity (> 46.67 m) at all sounding points with very good potential.Keywords: 1D-resistivity, Serayu watershed, resistivity log, aquifer, Somagede Village.

scholarly journals Electrical anisotropy due to gas hydrate-filled fractures

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. F173-F185 ◽  
Author(s):  
Ann E. Cook ◽  
Barbara I. Anderson ◽  
Alberto Malinverno ◽  
Stefan Mrozewski ◽  
David S. Goldberg
Keyword(s):  
Gas Hydrate ◽  
Unconsolidated Sediments ◽  
Electrical Anisotropy ◽  
High Resistivity ◽  
Continental Margins ◽  
Resistivity Measurements ◽  
Resistivity Logs ◽  
Logging While Drilling ◽  
Measured Resistivity

In 2006, the Indian National Gas Hydrate Program Expedition 01, or NGHP-01, discovered gas hydrate as fill in near-vertical fractures in unconsolidated sediments at several drilling sites on the Indian continental margins. These gas hydrate-filled fractures were identified on logging-while-drilling resistivity images. The gas hydrate-filled fracture intervals coincide with high measured resistivity at the NGHP-01 sites. High measured resistivity translates into high hydrate saturations via Archie’s equation; however, these high saturations contradict lower gas hydrate saturations determined from pressure core and chlorinity measurements. Also, in intervals with near-vertical gas hydrate-filled fractures, there is considerable separation between phase shift and attenuation resistivity logs, with [Formula: see text] resistivity measurements being significantly higher than [Formula: see text] resistivity measurements. We modeled the sensitivity of the propagation resistivity measurements in the gas hydrate-filled fracture intervals at NGHP-01 Sites 5 and 10. Near-vertical hydrate-filled fractures can cause the abnormally high resistivity measurements in vertical holes due to electrical anisotropy. The model suggests the gas hydrate saturations in situ are usually significantly lower than those calculated from Archie’s equation. In addition, these modeled gas hydrate saturations generally agree with the lower gas hydrate saturations obtained from pressure core and chlorinity measurements at NGHP-01 Sites 5 and 10.

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