Fault Planes Materials Fill Characteristics, UAE

2021 ◽  
Author(s):  
Abdelwahab Noufal
Keyword(s):  
Fault Plane ◽  
Salt Flux ◽  
Abu Dhabi ◽  
Sedimentary Sequences ◽  
Good Surface ◽  
Slip Surfaces ◽  
Fault Zone Architecture ◽  
Well Data ◽  
Transfer Faults ◽  
Basin System

Abstract Abu Dhabi subsurface fault populations triggered basin system in diverse directions, because of their significant role as fluid pathways. Studying fault infill materials, fault geometries, zone architecture and sealing properties from outcrops as analogues to the subsurface of Abu Dhabi, and combining these with well data and cores are the main objectives of this paper. The fault core around the fault plane and in areas of overlap between fault segments and around the fault tip include slip surfaces and deformed rocks such as fault gouge, breccia, and lenses of host rock, shale smear, salt flux and diagenetic features. Structural geometry of the fault zone architecture and fault plane infill is mainly based on the competency contrast of the materials, that are behaving in ductile or in a brittle manner, which are distributed in the subsurface of Abu Dhabi sedimentary sequences with variable thicknesses. Brittleness is producing lenses, breccia and gouge, while, ductile intervals (principally shales and salt), evolved in smear and flux. The fault and fractures are behaving in a sealy or leaky ways is mainly dependent on the percentage of these materials in the fault deformation zone. The reservoir sections distancing from shale and salt layers are affected by diagenetic impact of the carbonates filling fault zones by recrystallized calcite and dolomite. Musandam area, Ras Al Khaima (RAK), and Jabal Hafit (JH) on the northeast- and eastern-side of the UAE represents good surface analogues for studying fault materials infill characteristics. To approach this, several samples, picked from fault planes, were analysed. NW-trending faults system show more dominant calcite, dolomite, anhydrites and those closer to salt and shale intervals are showing smearing of the ductile infill. The other linked segments and transfer faults of other directions are represented by a lesser percentage of infill. In areas of gravitational tectonics, the decollement ductile interval is intruded in differently oriented open fractures. The studied outcrops of the offshore salt islands and onshore Jabal Al Dhanna (JD) showing salt flux in the surrounding layers that intruded by the salt. The fractures and faults of the surrounding layers and the embedment insoluble layers are highly deformed and showing nearly total seal. As the salt behaving in an isotropic manner, the deformation can be measured clearly by its impact on the surrounding and embedment's insoluble rocks. The faults/fractures behaviour is vicious in migrating hydrocarbons, production enhancement and hydraulic fracturing propagation.

Application of Seismic Sequence Stratigraphy for Delineating Mishrif Prospects in Western Onshore, Abu Dhabi, UAE

2021 ◽  
Author(s):  
Subrata Chakraborty ◽  
Monica Maria Mihai ◽  
Nacera Maache ◽  
Gabriela Salomia ◽  
Abdulla Al Blooshi ◽  
...  
Keyword(s):  
Abu Dhabi ◽  
Seismic Sequence ◽  
Large Area ◽  
Oil Accumulation ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
Seismic Sequence Stratigraphy ◽  
Well Data ◽  
Seismic Reflectors ◽  
Sweet Spots

Abstract In Abu Dhabi, the Mishrif Formation is developed in the eastern and western parts conformably above the Shilaif Formation and forms several commercial discoveries. The present study was carried out to understand the development of the Mishrif Formation over a large area in western onshore Abu Dhabi and to identify possible Mishrif sweet spots as future drilling locations. To achieve this objective, seismic mapping of various reflectors below, above, and within the Mishrif Formation was attempted. From drilled wells all the available wireline data and cores were studied. Detailed seismic sequence stratigraphic analysis was carried out to understand the evolution of the Mishrif Formation and places where the good porosity-permeability development and oil accumulation might have happened. The seismic characters of the Mishrif Formation in dry and successful wells were studied and were calibrated with well data. The Mishrif Formation was deposited during Late Cretaceous Cenomanian time. In the study area it has a gross thickness ranging from 532 to 1,269 ft as derived from the drilled wells; the thickness rapidly decreases eastward toward the shelf edge and approaching the Shilaif basin. The Mishrif was divided into three third-order sequences based on core observations from seven wells and log signatures from 25 wells. The bottom-most sequence Mishrif 1.0 was identified is the thickest unit but was also found dry. The next identified sequence Mishrif 2.0 was also dry. The next and the uppermost sequence identified as Mishrif 3.0 shows a thickness from 123 to 328 ft. All the tested oil-bearing intervals lie within this sequence. This sequence was further subdivided into three fourth-order sequences based on log and core signatures; namely, Mishrif 3.1, 3.2, and 3.3. In six selected seismic lines of 181 Line Km (LKM) cutting across the depositional axis, seismic sequence stratigraphic analysis was carried out. In those sections all the visible seismic reflectors were picked using a stratigraphic interpretation software. Reflector groups were made to identify lowstand systems tract, transgressive systems tract, maximum flooding surface, and highstand systems tract by tying with the observations of log and core at the wells and by seismic signature. Wheeler diagrams were generated in all these six sections to understand the lateral disposition of these events and locales of their development. Based on stratigraphic analysis, a zone with likely grainy porous facies development was identified in Mishrif 3.0. Paleotopography at the top of Mishrif was reconstructed to help delineate areas where sea-level fall generated leaching-related sweet spots. Analysis of measured permeability data identified the presence of local permeability baffles affecting the reservoir quality and hydrocarbon accumulation. This study helped to identify several drilling locations based on a generic understanding of the Mishrif Formation. Such stratigraphic techniques can be successfully applied in similar carbonate reservoirs to identify the prospect areas.

scholarly journals Petrological and Tectonostratigraphic Evidence for a Mid Ordovician Rift Pulse on the Arabian Peninsula

GeoArabia ◽  
1999 ◽  
Vol 4 (4) ◽  
pp. 467-500 ◽  
Author(s):  
W. Heiko Oterdoom ◽  
Mike A. Worthing ◽  
Mark Partington
Keyword(s):  
Tectonic Setting ◽  
Late Ordovician ◽  
Mafic Rocks ◽  
Early Ordovician ◽  
Sedimentary Sequences ◽  
Field Investigations ◽  
Clastic Sediments ◽  
Step Heating ◽  
Well Data ◽  
Uplift And Erosion

ABSTRACT During late Early Ordovician times an increase in the rate of subsidence in the Ghaba Salt Basin and western South Oman Salt Basin is suggested by the thick sequence of continental clastics of the Ghudun Formation. After a phase of rift-shoulder uplift and erosion, related to a renewed pulse of extension which may have initiated diapiric growth of salt structures in the Ghaba Salt Basin, sedimentation resumed again in the Mid Ordovician. During this period, the center of deposition shifted to the Saih Hatat area in North Oman. This paper documents seismic and well data, field investigations and petrological study of potassic mafic rocks from the Huqf area which were intruded in the eastern side of the Ghaba Salt Basin. A Mid Ordovician age of 461 ± 2.4 million years has been established for these rocks by the Argon-Argon step heating method. Analogy with the petrology and setting of similar potassic mafic rocks from the Rio Grande Rift in the western United States of America suggests that they were intruded into the shoulder of an intra-continental rift. The data provide the first clear evidence of a pulse of rift-shoulder uplift in the Huqf area during the Mid Ordovician. The 3-kilometer-thick Mid to Late Ordovician clastic sediments of the Amdeh Formation in North Oman, together with the occurrence of abnormally thick sedimentary sequences and volcanics in the Tabas Graben in Iran, are consistent with a period of break-up of eastern Gondwana. Together, the Ghaba-Saih Hatat and Tabas Basins are considered to be part of a failed rift arm. These observations further improve our regional knowledge of the Early to Late Ordovician tectonic setting of Oman and will assist in unlocking the hydrocarbon potential of classical rift-related structures consisting of early-rift Early Ordovician sand-prone reservoirs sealed by syn-rift Mid to Late Ordovician marine shales.

Geological and geophysical studies of buried valleys and their fills near Elora and Rockwood, Ontario

1994 ◽  
Vol 31 (12) ◽  
pp. 1838-1848 ◽  
Author(s):  
J. P. Greenhouse ◽  
P. F. Karrow
Keyword(s):  
Epithermal Neutron ◽  
Single Point ◽  
Low Frequency ◽  
Last Interglacial ◽  
Sedimentary Sequences ◽  
Transient Electromagnetic ◽  
Quaternary Sequences ◽  
Natural Gamma ◽  
Geophysical Logs ◽  
Well Data

Buried bedrock valleys are of economic interest for groundwater and engineering studies, and of scientific interest for the sedimentary sequences they may contain. Two buried valleys, about 60 m deep, north and northeast of Guelph, Ontario, are tributary to the major Dundas Valley southwest of Guelph. Located initially from water well data, their locations and geometry were refined with surface geophysics, including very low frequency resistivity, terrain conductivity, resistivity, transient electromagnetic, gravity, and seismic methods. Useful data are obtained roughly in proportion to cost. Cored and rotary holes in the two valleys were followed by geophysical downhole logging with normal electric, spontaneous potential, single-point resistance, calliper, neutron – epithermal neutron, gamma–gamma, and natural gamma methods. Cores revealed multi-till sequences in the upper parts of the holes and, together with geophysical logs and their interpreted electrofacies, indicate the presence of underlying uniform, pollen-bearing (pine and spruce dominate) lacustrine fills. These fills and the buried valleys containing them are interpreted to be perhaps as old as the last interglacial. Buried valleys are fruitful targets for the discovery of older Quaternary sequences.

Role of Well Logs and Seismic Data Conditioning in Improving the Imaging of Complex Reservoirs from Abu Dhabi

2021 ◽  
Author(s):  
Khalid Obaid ◽  
Muhammad Aamir ◽  
Tarek Yehia Nafie ◽  
Omar Aly ◽  
Widad Krissat ◽  
...  
Keyword(s):  
Seismic Data ◽  
Drilling Fluid ◽  
Rock Physics ◽  
Seismic Inversion ◽  
Well Logs ◽  
Abu Dhabi ◽  
Residual Noise ◽  
Data Conditioning ◽  
Well Data

Abstract Rock physics/seismic inversion is a powerful tool that deliver information about intra-wells rocks elastic attributes and reservoir properties such as porosity, saturation and rock lithology classification. In principle, inversion is like an engine that should be fueled by proper input quality of both seismic and well data. As for the well data, sonic and density logs measure the rock properties a few inches from the borehole. Reliability of sonic transit-time and bulk density logs can be affected by large and rapid variation in the diameter and shape of the borehole cross-section, as well as the process of drilling fluid invasion. The basic assumption for acoustic well logs editing and conditioning is to use other recorded logs (not affected by bad-hole conditions) in a Multivariate-Regression Algorithm. In addition, Fluid Substitution was implemented to correct for the mud invasion that affects the acoustic and elastic properties based on the PVT data for fluid properties computation. The logs were then quality checked by multiple cross-plotting comparisons to the standard Rock-physics trends templates. As for seismic data, there are several factors affecting the quality of surface seismic data including the presence of residual noise and multiples contamination that caused improper amplitude balancing. Optimizing the seismic data processing for the inversion studies require reviewing and conditioning the seismic gathers and pre-stack volumes, guided by a deterministic seismic-to-well tie analysis after every major stage of the processing sequence. The applied processes are mainly consisting of Curvelet domain noise attenuation to attenuate residual noise. This was followed by high resolution Radon anti-multiple to attenuate residual surface multiples and Extended interbed multiple prediction to attenuate interbed multiples. In addition, Offset dependent amplitude and spectral balancing were applied to maintain the seismic amplitudes fidelity. This paper will illustrate a case from Abu Dhabi where data conditioning results improved the Hydrocarbon saturated carbonates vs brine saturated carbonate and the lithology predictions, leading to optimizing field development plans and drilling operations.

Cased-Hole Standalone Evaluation Succeeds in the Absence of Openhole Data

2021 ◽  
Vol 73 (02) ◽  
pp. 61-62
Author(s):  
Judy Feder
Keyword(s):  
Water Saturation ◽  
Gas Production ◽  
Carbonate Reservoirs ◽  
Abu Dhabi ◽  
Well Testing ◽  
Gas Reservoirs ◽  
Formation Evaluation ◽  
Potential Reservoir ◽  
Static Modeling ◽  
Well Data

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 202894, “Cased Hole Standalone Evaluation: Breaking the Barrier To Successfully Evaluate Challenging Deep Carbonate Reservoirs,” by Pradeep Menon and Carey Mills, ADNOC, and Suvodip Dasgupta, SPE, Schlumberger, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually from 9-12 November. The paper has not been peer reviewed. Accurate petrophysical evaluations (formation lithology, porosity, and water saturation) are essential in characterizing potential reservoir zones and estimating resources in place. Typically, these evaluations rely on acquisition of openhole logging measurements; however, this is not always possible. The complete paper outlines two examples from tight gas reservoirs in two separate fields offshore Abu Dhabi in which openhole data could not be acquired and petrophysical analysis was undertaken using cased-hole log data. These evaluations successfully identified gas-saturated porous intervals in each well, one of which was successfully flow-tested. Introduction A growing need exists to increase gas production in the UAE. As a result, specific gas-production targets have been mandated from development of currently undeveloped deep gas carbonate reservoirs such as the Permo-Triassic Khuff formation, the middle Jurassic Araej formation, and the Permian Pre-Khuff Unayzah and Berwarth formations. Recent appraisal wells have aimed at evaluating these reservoirs systematically by acquiring a good suite of openhole logs, cutting conventional cores, and conducting well-testing operations. These well data are combined with an evolving regional understanding to better assess and ultimately develop these complex formations. An accurate petrophysical evaluation requires the petrophysicist to develop a realistic evaluation of formation lithology, porosity, and water saturation. These parameters provide the foundations for further work such as static modeling stands, and they must be robust. The Upper Khuff is composed of dolomite occasionally grading to calcareous dolomite with minor interbeds of claystone and anhydrite. In core and cuttings, the dolomite in the uppermost section exhibits a grainstone texture with poor intercrystalline/intergranular porosity. The Lower Khuff is composed of very hard dolomite in part grading to calcareous dolomite, medium-to-dark grey-brown in places, with occasional very-fine-to-medium grainstone texture and very poor intercrystalline porosity. In this paper, the Upper and Lower Araej members are interpreted to have been deposited in an open, marine- circulation shelfal environment, while the Uweinat member is considered to have been deposited in a more- restricted circulation setting with-in a similar shelfal environment. The Barrier Openhole logging generally is the preference for formation evaluation because it represents the simplest environments and benefits from a comprehensive list of available measurements. The variety of tools and diversity of output data available make openhole log acquisition the gold standard for formation evaluation. However, in certain situations in which openhole logging is not possible because of borehole conditions (re-entry of old cased wells, wellbore instability, over-pressure), no option exists other than acquiring petrophysical data in a cased-hole environment.

scholarly journals A deep seimic reflection line in the Danish Central Graben

1998 ◽  
Vol 44 ◽  
pp. 151-159
Author(s):  
L Klinkby ◽  
N. Balling ◽  
J. Liboriussen
Keyword(s):  
Normal Fault ◽  
Seismic Profiles ◽  
Depth Migration ◽  
Mantle Boundary ◽  
Sedimentary Sequences ◽  
Time Migration ◽  
Crustal Thinning ◽  
Crystalline Crust ◽  
Well Data ◽  
Zechstein Salt

Results are presented from a deep seismic reflection line, recorded to 16 seconds trave1 time, across the Coffee Soil Fault in the southern part of the Danish Central Graben. Data processing has been focused on the deeper parts of the sedimentary sequences, the crystalline crust and the crust-mantle boundary. Depth migration is performed down to 15 km depth, and time migration is performed on the entire section. The Coffee Soil Fault is clearly imaged as a normal fault dipping about 45" from about 2.5 to 9 km depth. Interpretation of the sedimentary sequences is constrained by well data and shows an almost uniform 2 km thick unit of post-chalk deposits. The thickness of the Mezosoic sequences is to a large extent controlled by faulting and highly influenced by movements of Zechstein salt. They exceed 4 km of thickness in the halfgraben immediately west of the Coffee Soil Fault. Large block-faulted pre-Zechstein units of more than 2 km thickness are seen indicating a total depth of at least 8 km to the crystalline basement. The crystalline crust is generally non-reflective. Around 11 seconds two-way trave1 time (about 28 km depth) reflectivity interpreted as the crust-mantle boundary (Moho) is observed. Comparison with other deep seismic profiles across the Central Graben is taken to indicate a local crustal thinning by a factor of 1.5 associated with graben formation by extension.

scholarly journals Orientationsstruktur der Talanlagen in der Schweiz

1979 ◽  
Vol 34 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Adrian E. Scheidegger
Keyword(s):  
Stress Field ◽  
Fault Plane ◽  
Rock Joints ◽  
Strong Indication ◽  
Fault Plane Solutions ◽  
Well Data ◽  
River Valleys

Abstract. The orientation of the Valleys in Switzerland shows a remarkable symmetry. It is the aim of this paper to represent this symmetry in numerical terms and to seek a physical cause thereof. For this purpose, the valley directions have been «rectified» (i. e. straightened) by considering them as edges in a graph. In this fashion, the distribution of orientations can be represented numerically and, in consequence, can be analyzed statistically. It is shown that the preferred orientations are ENE and SSE, which is the same as the preferred orientations of the strikes of the rock-joints in the region. Inasmuch as the joints are thought to be caused by the neotectonic stress field, the coincidence of the orientations of joints and river valleys is a strong indication that the latter are determined by the same neotectonic stress field as well. Data from fault plane solutions of earthquakes support this contention.

scholarly journals The Sedimentary Record of Paleogene Sequences in Sarawak, Malaysia

2021 ◽  
Vol 47 (1) ◽  
pp. 33-56
Author(s):  
Franz L. Kessler ◽  
John Jong ◽  
Mazlan Madon
Keyword(s):  
South China Sea ◽  
South China ◽  
Late Eocene ◽  
Peninsular Malaysia ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Sedimentary Sequences ◽  
Depositional Settings ◽  
Well Data

In this paper, we compare the oldest Tertiary sedimentary sequences in the south ern margin of the South China Sea based on outcrop and well data along the Sarawak margin, northern Borneo. Paleogene rocks in Sarawak are present in three tectono stratigraphic zones and represent three depositional settings. Outcrops and deep exploration wells in the Miri Zone indicate shelfal clastics, carbonates, and clay dominated neritic sediments. In the Sibu Zone (Rajang Fold Thrust Belt), Late Cretaceous to Late Eocene deep marine clastic sediments indicate a shallowing upward of the depositional basin, which was later buried to great depths (?) and metamorphosed. In the Kuching Zone, the Kayan and Plat eau sandstones represent a fluvial dominated non marine depositional setting. There are two major unconformities within the Paleogene of Sarawak: the Rajang Unconformity, dated as approximatively 37 Ma, and the younger near Top Eocene (a.k.a. Base Oligocen e) unconformity of 33.7 Ma. The likely presence of Eocene strata in the margins of Sundaland is associated with an early phase of regional extensional tectonism, which was also observed in the Penyu and Malay basins, offshore Peninsular Malaysia, and is probably related to the onset of rifting of the South China Sea continental crust.

Sign in / Sign up

Export Citation Format

Share Document