Enhancing Stratigraphic Framework Consistency Using Spectral Gamma-Ray Data

2021 ◽  
Author(s):  
Reza Satria Nugraha ◽  
Oliver Esteva Tumbarinu
Keyword(s):  
Gamma Ray ◽  
Stratigraphic Correlation ◽  
K Value ◽  
Shallow Marine ◽  
Field Development ◽  
Structural Framework ◽  
Stratigraphic Framework ◽  
Starting Point ◽  
Bottom To Top ◽  
Clay Type

Abstract Stratigraphic correlation is crucial for reservoir characterization; therefore, it requires more advanced methods and techniques to reduce the stratigraphic correlation uncertainty, especially when variation in lateral facies is high. The studied formations from bottom to top consist of fluvial to marginal marine X Formation, shallow marine Y Formation, and fluvial distributary channels to estuarine Z Formation. Spectral gamma-ray logs give additional consistent information on lithological composition that can support identification of boundary between formations within the stratigraphic framework. Wells with a full section of Y Formation, core, palynology, and spectral gamma-ray were selected as key wells. The top and base of the Y Formation were picked using conventional logs refined by a thorium/potassium (Th/K) ratio log and cross plot with core and palynology data as validations. The internal Y Formation markers were also picked with the aid of the Th/K cross plots. The top picking criteria from the key wells was implemented to the rest of the wells across the field with consistency. The uniform low Th/K ratio log (<3.5) across the Y Formation indicates illite as the dominant clay type, confirmed by X-ray diffraction (XRD) data with an average of more than 80%. The character is consistent with the interpreted depositional environment. This character makes the Y Formation stand out from the overlying Z and the underlying X formations. The change from X to Y Formation is defined by the decrease of the Th/K ratio log, from high kaolinite content to illite dominated environment. Inversely, the top of the Y Formation (base of Z) is indicated by the increase of the Th/K ratio log moving from shallow marine Y Formation to the fluvial-influenced Z Formation. The Th/K cross plot indicates different clusters amongst the studied formations and the internal Y zonation. The X Formation is located in the high Th and low K area where kaolinite is predominant, related to fluvial environment. The case is similar for the Z Formation but with more influence of mixed-clay type. The Y Formation shows clear clustering along the mixed-clay and illite window. Internal Y zonation displays, from bottom to top, an increasing K value within the clusters. This method provides a semi-quantitative interpretation to define the studied formations boundaries and the Y Formation internal zonation. This study has increased the consistency of the studied formations’ stratigraphic and structural framework. This consistency has, in turn, fine-tuned the structural framework and aided field development through better geosteering and lateral well placements. These results are a valuable starting point to refine and extend the work to other areas.

Sequence stratigraphic principles applied to the analysis of borehole microseismic data

2014 ◽  
Vol 2 (3) ◽  
pp. SG15-SG23
Author(s):  
Carlos Cabarcas ◽  
Roger Slatt
Keyword(s):  
Hydraulic Fracturing ◽  
Gamma Ray ◽  
Sensor Arrays ◽  
Data Set ◽  
Field Development ◽  
Sequence Stratigraphic ◽  
Microseismic Data ◽  
Stratigraphic Framework ◽  
Triple Array ◽  
Stacking Patterns

Based on a sequence stratigraphic framework developed using gamma ray stacking patterns, we have identified brittle-ductile couplets, which allow us to better interpret the microseismic response recorded during a single-stage hydraulic fracture stimulation treatment monitored from three strategically located observation wells. We have analyzed and compared hydraulic fracturing results inferred by individual processing of microseismic data acquired from horizontal and vertical sensor arrays, as well as the results from simultaneously processing the signals recorded by all three sensors. Ultimately, we have decided in favor of the triple array simultaneous solution as the most useful data set to interpret the stimulation treatment due to the location of the microseismic events coupled with the theoretical expectation from our sequence stratigraphic framework. The final data set has not only allowed us to better interpret the hydraulic fracturing results, but also helped us improve recommendations in support of the field development campaign.

scholarly journals Tectonic control on the stratigraphic framework of Late Pleistocene and Holocene deposits in Marajó Island, State of Pará, eastern Amazonia

2010 ◽  
Vol 82 (2) ◽  
pp. 439-449 ◽  
Author(s):  
Dilce F. Rossetti
Keyword(s):  
Late Quaternary ◽  
Fault Reactivation ◽  
Passive Margin ◽  
Stratigraphic Correlation ◽  
Sedimentary Records ◽  
Stratigraphic Framework ◽  
Island State ◽  
Marajó Island ◽  
Northern Brazil

The traditional view that the Brazilian Amazonia is located in a tectonically stable area since the Cretaceous is changing in front of the increasing documentation of fault reactivations even during the Holocene. How the sedimentary record has responded to these events is an issue that remains to be approached with basis on field data. This work focuses on the stratigraphic correlation of late Quaternary deposits from eastern Marajó Island, with the goal of demonstrating the role of fault reactivation on the origin and preservation of these deposits. Despite the location in a stable platform of a continental passive margin, three studied stratigraphic units display significant vertical offsets that define two depocenters that are better explained through tectonic displacements. This interpretation is reinforced by several morphostructural features related to faults that occur between the studied drills. Without the influence of tectonics, sediment preservation in this characteristically low-lying terrain would have been negligible. The results of the present work motivate to look for other tectonically-influenced areas in Amazonia, which similarly might have acted as sites for sediment accommodation during the late Quaternary. These sedimentary records have great potential to be the source of valuable information for reconstructing Quaternary geological events in Northern Brazil.

QUALITATIVE ANALYSIS OF SPECTRAL GAMMA RAY DATA AS A TOOL FOR FIELDWIDE AND REGIONAL STRATIGRAPHIC CORRELATION, ENDERBY TERRACE, CARNARVON BASIN, WESTERN AUSTRALIA

2001 ◽  
Vol 41 (1) ◽  
pp. 449
Author(s):  
A.P. Clare ◽  
A.J. Crowley
Keyword(s):  
Western Australia ◽  
Gamma Ray ◽  
Petroleum Industry ◽  
Stratigraphic Correlation ◽  
Environment Impact ◽  
Rock Types ◽  
Subsurface Environment ◽  
Detailed Assessment ◽  
Well Correlation ◽  
Carnarvon Basin

The use of wireline and core spectral gamma data as a tool for defining clay types and mineral assemblages in the subsurface environment has been widely used for many years within the petroleum industry. However, the qualitative use of radiometric data for interpreting rock types as used with airborne surveys in the mineral industry has not undergone detailed assessment as a well correlation tool.Applying the principles of qualitative airborne radiometric interpretation to the assessment of wireline spectral gamma ray data has proved extremely useful as a well correlation tool in the Carnarvon Basin of Western Australia. Data is presented from the Stag Field detailing the application of the technique as an effective fieldwide correlation tool. The sandstone reservoirs exhibit mineralogical variation and individual sand packages can be discontinuous. However, the major shale packages are laterally continuous and individual shales show remarkable character consistency over several kilometres. Such character continuity has proved a valuable correlation tool for confirming and refining the stratigraphic packages observed in the Cretaceous section of Stag.Success on the Stag Field led to application of the technique for regional correlations on the Enderby Terrace. The results of regional work show that correlations still hold when the technique is applied to correlations of over 70 km even though some lateral variation due to provenance and depositional environment impact on clay types was evident. Hence this qualitative approach of wireline log evaluation has proved an effective and valuable correlation tool.

Quantitative Biostratigraphy

1991 ◽  
Vol 4 ◽  
pp. 39-58 ◽  
Author(s):  
Lucy E. Edwards
Keyword(s):  
Stratigraphic Correlation ◽  
Starting Point ◽  
Quantitative Biostratigraphy ◽  
Operational Concept

I find myself in the position of discussing a rather unfortunate misnomer. In the first place, topics that traditionally have been called “quantitative biostratigraphy” seldom deal with quantities of anything. In the second place, much of “quantitative biostratigraphy” deals more with chronostratigraphy and geochronology than with biostratigraphy. The operational concept is time, not fossil content, although, of course, the fossil content is the starting point. Nonetheless, the phrase “quantitative biostratigraphy” is quite firmly entrenched in the working vocabulary and I will use it here. I will focus on three very different techniques that all involve stratigraphic correlation based on the ranges of fossils.

Geochemical and scintillometric characterization and correlation of amethyst geode-bearing Paraná lavas from the Quaraí and Los Catalanes districts, Brazil and Uruguay

2010 ◽  
Vol 147 (6) ◽  
pp. 954-970 ◽  
Author(s):  
LÉO A. HARTMANN ◽  
WILSON WILDNER ◽  
LAUREN C. DUARTE ◽  
SANDRO K. DUARTE ◽  
JULIANA PERTILLE ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Field Studies ◽  
Major And Trace Elements ◽  
Strong Variation ◽  
Stratigraphic Sequence ◽  
Stratigraphic Framework ◽  
World Class ◽  
Geochemical Studies ◽  
Bottom To Top ◽  
Aa Lava

AbstractGeochemical studies of the six lowermost lava flows of the Cretaceous Serra Geral Formation (Paraná volcanic province) in Quaraí (Brazil) and Artigas (Uruguay) were combined with flow-by-flow field studies of structures and scintillometric profiles to establish a consistent regional stratigraphic framework over at least 100 km. This greatly improves exploration capability for amethyst and agate geodes. A basalt, colada Mata Olho (Alegrete facies, Serra Geral Formation), was the first lava to flow over the ancient Botucatu desert in the region, but an andesite, colada Catalán, overstepped this basalt in many places, perhaps palaeohighs. Four basaltic andesites complete the lava stratigraphy in this formation, adding up to 300 m of lavas. The stratigraphic sequence of contrasting lava compositions is 51.0 wt% SiO2 in the first lava, followed by 57.5, 52.5, 56.0, 53.0 and finally 54.5 wt% SiO2. Overall MgO variation is between 2 and 7 wt%. All lavas in the two districts are low-Ti (<2.0 wt% TiO2) of the Gramado type. The characteristic contents of most major and trace elements (124 rock samples analysed) allow the ready identification of each lava. Contrasting rock chemistry also results in strong variation in scintillometric values (270 points measured in the field and nineteen continuous borehole profiles); from bottom to top of the stratigraphy, the cps values are 49±3.2, 123±10.3, 62±4.7, 94±4.6, ~45 and ~85. Colada Catalán has the structure of aa lava, particularly the contorted igneous banding and autobreccias in the upper and lower crusts. In some places, a 2 m thick, silicified sandstone layer lies on top of some coladas, and silicified sandstone forms breccias with volcanic rocks. Geochemistry of the six lavas indicates complex evolution, involving melting of lithospheric mantle, injection into the crust and assimilation of crust followed by fractional crystallization. This study indicates the possibility of world-class deposits of amethyst geodes on the Brazilian side of the border with Uruguay.

scholarly journals GEOPHYSICAL AND WELL CORELLATION ANALYSIS OF OGO FIELD: A CASE STUDY IN NIGER DELTA BASIN OF NIGERIA

2017 ◽  
Vol 36 (3) ◽  
pp. 729-733
Author(s):  
MO Ehigiator ◽  
NC Chigbata
Keyword(s):  
Gamma Ray ◽  
Water Saturation ◽  
Average Porosity ◽  
Resistivity Logs ◽  
Hydrocarbon Formation ◽  
Formation Resistivity ◽  
Well Correlation ◽  
Niger Delta Basin ◽  
4D Seismic ◽  
Bottom To Top

A suite of geophysical wire line logs were run in hole. The wells data were acquired from bottom to top and not top to bottom. Basically, we have the qualitative and the quantitative evaluation techniques.Qualitative means is usually used for identification of the type of lithology and also for the component of the formation. Quantitative is used to estimate numerically, the value of what is in the formation. The logs used for evaluation were: Spontaneous potential logs and the Gamma ray logs. These were used to determine the lithology of the formation. Resistivity logs were run in hole to also determine the water saturation in the formation. The Formation Density and the compensated Neutron logs were run in hole to differentiate the gaseous zone from the oil zone in the Hydrocarbon Formation Ogo1, Ogo2 and Ogo3 from well correlation depicts that the subsurface stratigraphy is that of sand – shale intercalations.  Two prominent hydrocarbon bearing reservoirs (R1and R2), at Depth 1563m and 1642mm respectively were identified. The reservoirs were found to have average porosity of 0.22, water saturation 0.43 and Hydrocarbon saturation of 0.57. The reservoirs have permeability of 1376m, volume of oil in place for reservoir 1 and 2 is 39900m3  and 9647 m3   respectively. More. Well correlations are recommended for proper drilling and well completions. 4D seismic acquisitions should be encouraged for proper view of the formation. http://dx.doi.org/10.4314/njt.v36i3.10

scholarly journals Characterizing and modeling the Upper Jurassic Arab-D reservoir using outcrop data from Central Saudi Arabia

GeoArabia ◽  
2014 ◽  
Vol 19 (2) ◽  
pp. 53-84
Author(s):  
Hassan Eltom ◽  
Osman Abdullatif ◽  
Mohammed Makkawi ◽  
Asaad Abdulraziq
Keyword(s):  
Saudi Arabia ◽  
Gamma Ray ◽  
Upper Jurassic ◽  
Major And Trace Elements ◽  
Carbonate Reservoir ◽  
Oil Fields ◽  
Small Scale ◽  
Well Spacing ◽  
Stratigraphic Framework

ABSTRACT Outcrop analogs are used to improve the characterization of reservoir stratigraphy, to understand subsurface facies architecture and heterogeneity, and to overcome the limitations associated with large inter-well spacing within individual oil fields. This study characterized and modeled outcropping strata equivalent to the Upper Jurassic Arab-D carbonate reservoir in Central Saudi Arabia. The study presents qualitative and quantitative sedimentological and petrographic descriptions of lithofacies associations and interprets them within a high-order stratigraphic framework using geostatistical modeling, spectral gamma-ray, geochemistry, petrography and micropaleontology. The sedimentological studies revealed three lithofacies associations, which are interpreted as a gentle slope platform depositional environment comprising nine high-frequency sequences. The biocomponents of the study area show a lower degree of diversity than the subsurface Arab-D reservoir; however, some key biofacies are present and provide indications of the nature of the paleoenvironments. The geochemical results show a strong correlation between the major and trace elements and the reservoir facies, and suggest that the concentrations of elements and their corresponding spectral gamma-ray logs follow the same general upward-shoaling pattern. The 3-D geocellular model captures small-scale reservoir variability, which is reflected in the petrophysical data distribution in the model. This investigation increases the understanding of the stratigraphy of the Arab-D reservoir and provides a general framework for zonation, layering, and lateral stratigraphic correlations.

scholarly journals Interpretation and Reconstruction of Depositional Environment and Petroleum Source Rock Using Outcrop Gamma-ray Log Spectrometry From the Huai Hin Lat Formation, Thailand

2021 ◽  
Vol 9 ◽  
Author(s):  
Chawisa Phujareanchaiwon ◽  
Piyaphong Chenrai ◽  
Kasira Laitrakull
Keyword(s):  
Depositional Environment ◽  
Gamma Ray ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Turbidity Currents ◽  
Stratigraphic Framework ◽  
Facies Associations ◽  
Mineral Compositions ◽  
Gamma Ray Log ◽  
Low K

Gamma ray logs are most useful in identifying subsurface lithology and interpreting depositional environments. This study highlights the use of outcrop gamma-ray logs along with outcrop observations and total organic carbon (TOC) analysis to provide the stratigraphic framework of the organic-rich rocks of Huai Hin Lat Formation in central Thailand. The study reveals five sedimentary facies including (1) structureless sandstone, (2) structured sandstone, (3) interbedded sandstone and siltstone, (4) interbedded mudstone and siltstone and (5) calcareous mudstone. These facies can be grouped into two facies associations; mudstone-dominated and sandstone-dominated facies associations. The depositional environment was interpreted as lacustrine basin-fill subdivided into deep lacustrine environment and sublacustrine fan associated with the turbidity currents. The total gamma-log characteristics are closely related to the lithologies controlled primarily by clay mineral compositions. Whist, the use of spectral gamma-ray can reveal more details on depositional environments and conditions. In this study, U concentrations is proven to be useful in highlighting organic-rich rocks in low K and Th concentration successions due to its ability to be fixed in clay minerals and organic materials under an anoxic condition. Thus, the U spectral gamma ray is suggested to combine with conventional gamma ray log for depositional environment and recognition of organic-rich rocks.

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