Fatehgarh lacustrine turbidite potential, Barmer Basin, India

2019 ◽  
Vol 38 (4) ◽  
pp. 280-285
Author(s):  
Priyabrata Chatterjee ◽  
Utpalendu Kuila ◽  
B. N. S. Naidu ◽  
Hriday Jyoti Bora ◽  
Anil Malkani ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Integrated Approach ◽  
Seismic Inversion ◽  
Seismic Facies ◽  
Reservoir Quality ◽  
High Quality ◽  
Passive Margins ◽  
Seismic Waveform ◽  
Barmer Basin ◽  
Environment Maps

Global discovered resources of oil and gas in giant stratigraphic and structural-stratigraphic combination traps have increased by nearly 50% in the last 17 years. Among the biggest contributors are the large discoveries in deepwater turbidite systems in passive margins and rift basins. The current study area is located in the Barmer Basin in northwestern India. Barmer Basin is a prolific petroliferous basin with major oil discoveries in structural plays including Mangala, Bhagyam, and Aishwariya fields. The principal reservoirs in the structural highs are high-quality fluvial sandstones of the Paleocene Fatehgarh Formation. Lacustrine turbidite plays have been discovered in the overlying Paleocene Barmer Hill Formation, albeit with moderate to poor reservoir quality. The potential exists, however, for finding off-structure lacustrine deepwater turbidite plays in the Paleocene Fatehgarh with reservoir quality comparable to the high-quality fluvial facies encountered updip in the structural plays. An integrated approach was adopted to identify stratigraphic entrapments across the basin to chase high-quality Fatehgarh reservoirs. Gross depositional environment maps integrating new geoscientific data were created, followed by well-calibrated seismic geomorphology and seismic facies interpretations to identify the distal lacustrine deepwater turbidite system fed by the updip fluvial Fatehgarh systems. Worldwide, the critical risk elements associated with such plays are reservoir presence, quality, and lateral seal. Geophysical tools like unsupervised seismic waveform classification, spectral decomposition, and seismic inversion were applied to the available seismic data, and the results were integrated with the regional geology and well facies information to derisk the critical risk segments.

Reservoir Quality Versus Completion Intensity: An Application of Supervised Fuzzy Clustering on Western Canadian Well Data

2021 ◽  
Author(s):  
Tamer Moussa ◽  
Hassan Dehghanpour ◽  
Melanie Popp
Keyword(s):  
Fuzzy Clustering ◽  
Oil And Gas ◽  
Approximate Reasoning ◽  
Design Parameters ◽  
Water Volume ◽  
Reservoir Quality ◽  
Reservoir Properties ◽  
High Quality ◽  
Tight Reservoirs ◽  
Well Data

ABSTRACT The industry is facing significant challenges due to the recent downturn in oil prices, particularly for the development of tight reservoirs. It is more critical than ever to 1) identify the sweet spots with less uncertainty and 2) optimize the completion-design parameters. The overall objective of this study is to quantify and compare the effects of reservoir quality and completion intensity on well productivity. We developed a supervised fuzzy clustering (SFC) algorithm to rank reservoir quality and completion intensity, and analyze their relative impacts on wells' productivity. We collected reservoir properties and completion-design parameters of 1,784 horizontal oil and gas wells completed in the Western Canadian Sedimentary Basin. Then, we used SFC to classify 1) reservoir quality represented by porosity, hydrocarbon saturation, net pay thickness and initial reservoir pressure; and 2) completion-design intensity represented by proppant concentration, number of stages and injected water volume per stage. Finally, we investigated the relative impacts of reservoir quality and completion intensity on wells' productivity in terms of first year cumulative barrel of oil equivalent (BOE). The results show that in low-quality reservoirs, wells' productivity follows reservoir quality. However, in high-quality reservoirs, the role of completion-design becomes significant, and the productivity can be deterred by inefficient completion design. The results suggest that in low-quality reservoirs, the productivity can be enhanced with less intense completion design, while in high-quality reservoirs, a more intense completion significantly enhances the productivity. Keywords Reservoir quality; completion intensity; supervised fuzzy clustering, approximate reasoning,tight reservoirs development

Seismic-based characterization of reservoir heterogeneity within the Meramec interval of the STACK play, Central Oklahoma

2020 ◽  
pp. 1-46
Author(s):  
William Neely ◽  
Ahmed Ismail ◽  
Mohammed Ibrahim ◽  
James Puckette
Keyword(s):  
Oil And Gas ◽  
Seismic Inversion ◽  
Well Logs ◽  
Reservoir Quality ◽  
High Porosity ◽  
3D Seismic ◽  
Horizontal Drilling ◽  
Wide Range ◽  
Porosity Heterogeneity

The Meramec interval within the “STACK” play of the Anadarko Basin in central Oklahoma has been recently at the epicenter of increased exploration and production of oil and gas. It has become one of the top target intervals of the “Mid-Continent” aided by the technological advancements in horizontal drilling and completion techniques. The Meramec interval, mainly composed of argillaceous siliciclastic sediments with varying amounts of carbonate cement, exhibits high porosity heterogeneity, which is theorized to be caused by varying amounts of clay and post-depositional calcite cement. Characterization of the porosity heterogeneity in the Meramec interval will improve our understanding of the wide range in Meramec oil and gas production volumes and reduce the risk associated with drilling and completion techniques. We completed an initial interpretation followed by inversion of 3D seismic data where we generated a detailed characterization of the porosity heterogeneity and overall reservoir quality within the Meramec interval over an area of approximately 150 square kilometers. We then used the 3D seismic volume and available well logs to map the vertical and lateral extents of the Meramec interval and identify possible structural elements that could affect the reservoir quality. A petrophysical analysis of the well logs confirmed porosity heterogeneity and variations in volumetric calculations of clay and carbonate minerals. Finally, we generated a set of porosity volumes using the acoustic impedance from seismic inversion and probabilistic neural network methods. The derived porosity volume helped us identify porous and non-porous intervals within the Meramec throughout the study area. The results improved our understanding of Meramec heterogeneity, further reducing the risk associated with well planning, drilling and completion.

A Holistic Design Approach for Considering Rogue Buckle Formation Due to Pipelay-Induced Out-of-Straightness

2010 ◽  
Author(s):  
Andrew Rathbone ◽  
Gary Cumming
Keyword(s):  
Design Process ◽  
Robust Design ◽  
Deep Water ◽  
Oil And Gas ◽  
Mechanical Design ◽  
Integrated Approach ◽  
High Quality ◽  
Global Buckling ◽  
Vessel Motion ◽  
Stability Issues

As oil and gas reserves become more hostile and more remote, the associated flowline mechanical design faces increasing challenges. The trend is that longer, larger diameter, hotter, and lighter (with increased insulation requirements, and minimal stability issues in deep water) flowlines are required. Global buckling is therefore an increasingly prevalent part of the design process of modern field developments. In order to ensure a robust global buckling design, all potential buckle triggers must be considered. A challenge for this is that imperfections introduced by pipelay can not be known until installation is complete. A common approach is therefore to consider high quality survey data from previous projects to characterise the severity of pipelay features for future projects. This paper considers the effect of pipelay catenary length, pipe-soil interaction, pipeline bending stiffness and vessel motion on the as-laid horizontal imperfections, and consequently details the interrelationship between the causes and effects of the imperfection. Further, there is an interrelationship between the severity of the feature, its resistance to buckling and the level of strain in the post-buckled state. An integrated approach is therefore advocated, to obtain a robust design range of imperfection sizes in a deterministic fashion.

Stratigraphic Trap Potential in the Lower Cretaceous Ratawi Interval, Partitioned Zone PZ, Saudi Arabia and Kuwait

2021 ◽  
Author(s):  
Ibrahim Hakam ◽  
Niall Toomey ◽  
Sujoy Ghose ◽  
Joe Ponthier ◽  
Jeremy Zimmerman
Keyword(s):  
Lower Cretaceous ◽  
Depositional Environment ◽  
High Energy ◽  
Seismic Inversion ◽  
Seismic Facies ◽  
Reservoir Quality ◽  
The North ◽  
Reservoir Development ◽  
Calcite Cement ◽  
Effective Seal

Abstract The Lower Cretaceous Ratawi Oolite Formation is among the most prolific reservoirs in the PZ, having produced a significant amount of oil since the 1950's. The Ratawi is interpreted as a low angle carbonate ramp, with high-energy grainstone facies developing on structural highs. Production is focused on these structural highs, with very few well penetrations off structure. Recent work has identified potential Ratawi stratigraphic traps in prograding clinoforms along the flanks of the North Fuwaris structural high. Core data from Ratawi wells illustrate the interplay of depositional environment and diagenesis on reservoir quality. Gross depositional environment (GDE) maps created from the integration of seismic facies and core observations indicate the stratigraphic trap lies in the ramp slope. Reservoir quality variability of the ramp slope across the PZ is explained by the diagenetic history of the Ratawi. Early equant calcite cement develops from substantial meteoric runoff and lowers porosity, while later dissolution enhances reservoir quality. The area of interest is isolated from potential meteoric inputs; we do not expect equant calcite cement or the associated reduction in reservoir quality. Seismic interpretation was performed on recently acquired PZ 3D data to map the Ratawi section. Clinoforms (inclined geometry) were mapped along the western flank of the North Fuwaris high. These facies appear to have developed as a result of progradation to the NW and are indicative of good reservoir development. Leads were generated using the depth structure and GDE maps, supported by amplitude extraction and seismic inversion volumes. Amplitudes extracted from the clinoform shows that the strongest anomaly is along the structurally highest part of the horizon and the anomaly weakens downdip. High amplitudes could be a proxy for reservoir (porosity), and sharp turn-off in amplitude might indicate that lateral and updip facies changes to non-reservoir which is needed for an effective seal. Recent seismic inversion performed on the Ratawi interval shows a good match between the Acoustic Impedance (AI) from logs and the computed AI from the seismic. The Ratawi Oolite appears as a low impedance interval between overlying Ratawi Limestone and underlying Makhul. Porosity estimated from AI volumes appear to support possible Ratawi reservoir development along the flanks of North Fuwaris and Wafra highs.

scholarly journals Dorado discovery – unlocking a major new oil and gas play in the Bedout Sub-basin

2020 ◽  
Vol 60 (2) ◽  
pp. 778
Author(s):  
Melissa Thompson
Keyword(s):  
Joint Venture ◽  
Oil And Gas ◽  
Seismic Inversion ◽  
Source Rocks ◽  
High Quality ◽  
Well Control ◽  
Light Oil ◽  
Set Up ◽  
Inversion Techniques

In 2014, Santos (formerly Apache and Quadrant Energy Limited) acquired an operated exploration position over most of the under-explored Bedout Sub-basin. A multi-year exploration program was subsequently executed, targeting plays within Middle Triassic fluvio-deltaic sediments of the Lower Keraudren and Archer formations. Initial wells at Phoenix South and Roc established the presence of high-quality reservoirs, source rocks and hydrocarbon fluids, but the commerciality of these discoveries was impeded by the lack of existing production infrastructure in this frontier basin. In 2018, Santos and its Joint Venture partner, Carnarvon Petroleum, drilled Dorado-1, targeting stacked Archer Formation reservoirs in an erosional truncation trap set up by a major canyon system. The well encountered light oil and/or condensate rich gas in high-quality reservoir sands at each of the target intervals. Despite limited well control, burial depths on the order of 4000 m and imperfect seismic data, the pre-drill prognosis was remarkably accurate, largely due to the application of modern seismic inversion techniques. Subsequent appraisal drilling undertaken during 2019 demonstrated the discovery is larger than originally anticipated and has significantly de-risked a future development. New seismic acquired during 2019 will be used to further improve the understanding of Dorado reservoirs and to mature follow-up prospects for future drilling.

scholarly journals The forming mechanisms of Oligocene combination/stratigraphic traps and their reservoir quality in southeast Cuu Long Basin offshore of Vietnam

2019 ◽  
Vol 22 (1) ◽  
pp. 185-195
Author(s):  
Chuc Dinh Nguyen ◽  
Xuan Van Tran ◽  
Kha Xuan Nguyen ◽  
Huy Nhu Tran ◽  
Tan Thanh Mai
Keyword(s):  
Oil And Gas ◽  
Integrated Approach ◽  
Gas Production ◽  
Reservoir Quality ◽  
Hydrocarbon Potential ◽  
Seismic Attribute ◽  
Oil And Gas Production ◽  
Seismic Sequence Stratigraphy ◽  
The One

To date, most of the oil and gas production in Cuu Long Basin (CLB) is contributed from structural traps, making them more and more depleted after years of exploitation. Exploration activities in CLB, therefore, are shifting towards other traps, including stratigraphic and/or combination ones. The results of exploration and appraisal activities in recent years have increasingly discovered more hydrocarbons in the Oligocene section; some of them were discovered in combination/ stratigraphic traps. Many studies on Oligocene targets in Southeast CLB have been carried out but only a few mention nonstructural traps. This leads to uncertainty about the forming mechanisms and distribution, as well as unevaluated hydrocarbon potential of these traps. An integrated approach- utilizing methods of seismic sequence stratigraphy, seismic attribute interpretation, and petrophysical/ petrographical analysis- was applied in this research to identify the forming mechanisms of Oligocene combination/ stratigraphic traps in southeast area of CLB and to evaluate their reservoir quality. The research results show that the key forming factor for stratigraphic traps of sand body is lithology change and the one for pinch-out stratigraphic traps is tapering off of sand layers landward or toward the horsts. The reservoir quality of these traps ranges from moderate to good. By integratedly applying the methods, the forming mechanisms and reservoir quality of Oligocene stratigraphic traps could be delineated. In order to optimize the next-stage exploration strategy in CLB, detailed studies on petroleum system, especially top and bottom seals, and the hydrocarbon potential of these stratigraphic traps, need to be carried out.  

scholarly journals Batch seismic inversion using the iterative ensemble Kalman smoother

2021 ◽  
Author(s):  
Michael Gineste ◽  
Jo Eidsvik
Keyword(s):  
Seismic Data ◽  
Time Windows ◽  
Seismic Inversion ◽  
Efficient Estimation ◽  
Solution Strategy ◽  
Adaptive Procedure ◽  
Waveform Data ◽  
Kalman Smoother ◽  
Seismic Waveform ◽  
Single Batch

AbstractAn ensemble-based method for seismic inversion to estimate elastic attributes is considered, namely the iterative ensemble Kalman smoother. The main focus of this work is the challenge associated with ensemble-based inversion of seismic waveform data. The amount of seismic data is large and, depending on ensemble size, it cannot be processed in a single batch. Instead a solution strategy of partitioning the data recordings in time windows and processing these sequentially is suggested. This work demonstrates how this partitioning can be done adaptively, with a focus on reliable and efficient estimation. The adaptivity relies on an analysis of the update direction used in the iterative procedure, and an interpretation of contributions from prior and likelihood to this update. The idea is that these must balance; if the prior dominates, the estimation process is inefficient while the estimation is likely to overfit and diverge if data dominates. Two approaches to meet this balance are formulated and evaluated. One is based on an interpretation of eigenvalue distributions and how this enters and affects weighting of prior and likelihood contributions. The other is based on balancing the norm magnitude of prior and likelihood vector components in the update. Only the latter is found to sufficiently regularize the data window. Although no guarantees for avoiding ensemble divergence are provided in the paper, the results of the adaptive procedure indicate that robust estimation performance can be achieved for ensemble-based inversion of seismic waveform data.

An Innovative Approach of Using Engineering Modelling to Improve Drilling Dynamics in Western Rajasthan, India

2021 ◽  
Author(s):  
Shailesh Prakash ◽  
Mohammad Zayyan ◽  
Ole Gjertsen ◽  
Manuel Centeno Acuna ◽  
Piyush Kumar Kulshrestha ◽  
...  
Keyword(s):  
Torsional Oscillation ◽  
Predictive Modelling ◽  
Integrated Approach ◽  
Vibration Monitoring ◽  
Hole Drilling ◽  
Volcanic Complex ◽  
Gas Field ◽  
Stick Slip ◽  
Unique Type ◽  
Barmer Basin

Abstract Raageshwari Deep Gas (RDG) field is a major gas field in the Barmer Basin of Rajasthan, India which comprises of a tight gas-condensate reservoir within the underlying thick Volcanic Complex. The Volcanic Complex comprises two major units – upper Prithvi Member (Basalt) and lower Agni Member (Felsics interbedded with older basalt). The production zone is drilled in 6" and has historically seen high level of shock & vibrations (S&V) and stick-slip (S&S) leading to multiple downhole tool failures and poor rate of penetration (ROP). Individual changes in Bit and bottom hole drilling assembly (BHA) design were not able to give satisfactory results and hence an integrated approach in terms of in-depth formation analysis, downhole vibration monitoring, correct predictive modelling, bit and BHA design was required. A proprietary formation analysis software was used to map the entire RDG field to understand the variation in terms of formation compactness, abrasiveness and impact (Figure 1,2,3 & 4). The resulting comprehensive field map thus enabled us to accurately identify wells that would be drilling through more of problematic Felsics and where higher S&V and S&S should be expected. To better understand the vibrations at the point of creation, i.e., bit, a downhole vibration recording tool was used to record vibration & stick-slip data at a frequency of 1024Hz. This tool picked up indication of a unique type of vibration occurring downhole known as High Frequency Torsional Oscillation (HFTO), that was quite detrimental to the health of bit and downhole tools. A proprietary predictive modelling software was used to optimize the bit-BHA combination to give least amount of S&V and S&S. Data from the downhole vibration recording tool, formation mapping software and offset bit designs was used to design a new bit with ridged diamond element cutters and conical diamond element cutters to drill through the highly compressive and hard basalt. The predictive modelling software identified a motorized Rotary steerable assembly (RSS) to give the best drilling dynamics with the newly designed bit. The software predicted much lower S&V and S&S with higher downhole RPM which was possible with the help of motorized RSS. Implementing the above recommendations from the various teams involved in the project, drilling dynamics was vastly improved and ROP improvement of about 45% was seen in the field. This combination was also able to drill the longest section of Felsics (826m) with unconfined compressive strengths as high as 50,000 psi in a single run with excellent dull condition of 0-1-CT-TD This paper will discuss in detail the engineering analyses done for improving drilling dynamics in field along with how HFTO was identified in field and what steps were taken to mitigate it.

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