Shell (Malaysia)

Abstract Models and concepts of sandstone diagenesis developed over the past two decades are currently employed with variable success to predict reservoir quality in hydrocarbon exploration. Not all of these are equally supported by quantitative data, observations, and rigorous hypothesis testing. Simple plots of sandstone porosity versus extrinsic parameters such as current subsurface depth or temperature are commonly extrapolated but rarely yield accurate predictions for lithified sandstones. Calibrated numerical models that simulate compaction and quartz cementation, when linked to basin models, have proven successful in predicting sandstone porosity and permeability where sufficient analog information regarding sandstone texture, composition, and quartz surface area is available. Analysis of global, regional, and local data sets indicates the following regarding contemporary diagenetic models used to predict reservoir quality. (1) The effectiveness of grain coatings on quartz grains (e.g., chlorite, microquartz) as an inhibitor of quartz cementation is supported by abundant empirical data and recent experimental results. (2) Vertical effective stress, although a fundamental factor in compaction, cannot be used alone as an accurate predictor of porosity for lithified sandstones. (3) Secondary porosity related to dissolution of framework grains and/or cements is most commonly volumetrically minor (<2%). Exceptions are rare and not easily predicted with current models. (4) The hypothesis and widely held belief that hydrocarbon pore fluids suppress porosity loss due to quartz cementation is not supported by detailed data and does not represent a viable predictive model. (5) Heat-flow perturbations associated with allochthonous salt bodies can result in suppressed thermal exposure, thereby slowing the rate of quartz cementation in some subsalt sands.

Abstract This paper concerns the collation, quality control, and analysis of single-point field measurements from fixed sensors mounted on offshore platforms. In total, the quality-controlled database contains 122 million individual waves, of which 3649 are rogue waves. Geographically, the majority of the field measurements were recorded in the North Sea, with supplementary data from the Gulf of Mexico, the South China Sea, and the North West shelf of Australia. The significant wave height ranged from 0.12 to 15.4 m, the peak period ranged from 1 to 24.7 s, the maximum crest height was 18.5 m, and the maximum recorded wave height was 25.5 m. This paper will describe the offshore installations, instrumentation, and the strict quality control procedure employed to ensure a reliable dataset. An examination of sea state parameters, environmental conditions, and local characteristics is performed to gain an insight into the behavior of rogue waves. Evidence is provided to demonstrate that rogue waves are not governed by sea state parameters. Rather, the results are consistent with rogue waves being merely extraordinary and rare events of the normal population caused by dispersive focusing.

ABSTRACT Clavate (club-shaped) structures rimming mid-Cretaceous Burmese amber from Myanmar, previously misdiagnosed as fungal sporocarps, are shown to be domichnia (crypts) of martesiine bivalves (Pholadidae: Martesiinae). They are similar in form to Teredolites clavatus Leymerie, 1842 and Gastrochaenolites lapidicus Kelly & Bromley, 1984; however, the former identification is preferable, given that they are martesiine crypts in amber as opposed to a lithic substrate. Cross-cutting relationships between the clavate features and inclusions in the amber demonstrate that the features post-date hardening of the resin. The fills of the crypts are variable, including sand grade sediment of very fine to coarse sand grainsize, and sparry calcite cements. In some cases, the articulated valves of the pholadid bivalve responsible are visible inside the borings. However, one remarkable specimen contains two pairs of articulated shells ‘floating’ in amber, not associated with crypts; an observation that suggests that the resin was still liquid or soft when the bivalves were trapped in the resin. One individual is associated with an irregular sediment-filled feature and shows shell breakage. Formation of a solid rim around a liquid central volume has been documented in subaqueous bodies of resin in modern swamp forests, and argues for a close proximity between the amber-producing trees and a brackish water habitat for the bivalves. The presence of pyrite as thin films and crystal groups within Burmese amber is further consistent with such a depositional environment. Comparison of the size of pholadid body fossils with growth rates of modern equivalents allows the duration of boring activities to be estimated and suggests that small fossil pholadids in Burmese amber became trapped and died within 1–2 weeks of having settled on the resin. Larger examples present within well-formed domichnia formed in hardened resin. Since ‘hardground’ describes early lithified sediment as a substrate and ‘woodground’ describes wood as a substrate, the term ‘amberground’ is used here to described borings in an amber substrate.

ABSTRACT A fault zone model is presented which is capable of explaining the migration, distribution and trapping of hydrocarbons in Nigerian rollover structures. The main factor accounting for the occurrence of hydrocarbons in a rollover structure appears to be the presence of a large wedge of overpressured marine source-rock shale on the upthrown side of the structure bounding growth fault. The driving force for the migration is considered to be the fluid-pressure differential resulting from the juxtaposition of overpressured shale against initially hydropressured paralic sands across the fault. This mechanism can explain the presence of hydrocarbons in the lowermost series of paralic sands opposite overpressured shale but not that of shallower accumulations. Model experiments and outcrop studies in Germany have indicated that shear zones of normal faults in sand/shale sequences usually consist of smeared-in laminae of shale and wedges of sand. In Nigeria the spill points of accumulations in rollover structures often coincide with the highest point of contact of bounding growth fault and reservoir. These observations suggest that migration of hydrocarbons along major faults may occur along sandy stringers and wedges in shear zones. In this way, superimposed reservoirs can be successively filled with hydrocarbons when connections between hydrocarbon-bearing sand in the shear zone and the reservoir sand are available. INTRODUCTION Throughout the Niger Delta we find a sequence of under compacted marine clays (Akata Formation), overlain by paralic deposits (Agbada Form.), in turn covered by continental sands (Benin Form.). In the paralic interval growth fault associated rollover structures trapped hydrocarbons. The petroleum geology of the Niger Delta1,2 is characterised by the occurrence of multiple reservoirs in the imbricated and superimposed off flap cycles of the paralic interval. Typically, in a rollover structure virtually all available sands contain at least some hydrocarbons over an interval ranging from 1 500 to 6 000 ft, provided the caprock shales overlying the sands are sufficiently thick. The hydrocarbons are not of local origin because the shales in the paralic interval, although often having source-rock characteristics, have generally been found to be immature. The main source rock is thought to be the shale of the Akata Formation. Over most of the delta the upper part of the Akata shales can probably be considered mature source rock. A remarkable feature, common to all fields is, that nowhere do we observe trapping of hydrocarbons against the downthrown side of a growth fault, unless they are juxtaposed against an overpressured zone across the fault. In many reservoirs the fault intersection with the top of the reservoir appears to be the spill point of the accumulation. This seems to indicate that the growth faults form vertical conduits connecting successive reservoirs. Several studies have been carried out in Nigeria to learn more about the composition and structure of fault zones. A series of 1:20 scale diameter logs have been examined, which show that the widths of shear zones of normal faults in Nigerian oilfields generally range from less than a foot to about two feet.

Abstract Isolated carbonate buildups (ICBs) are commonly attractive exploration targets. However, identifying ICBs based only on seismic data can be difficult for a variety of reasons. These include poor-quality two-dimensional data and a basic similarity between ICBs and other features such as volcanoes, erosional remnants, and tilted fault blocks. To address these difficulties and develop reliable methods to identify ICBs, 234 seismic images were analyzed. The images included proven ICBs and other features, such as folds, volcanoes, and basement highs, which may appear similar to ICBs when imaged in seismic data. From this analysis, 18 identification criteria were derived to distinguish ICBs from non-ICB features. These criteria can be grouped into four categories: regional constraints, analysis of basic seismic geometries, analysis of geophysical details, and finer-scale seismic geometries. Systematically assessing the criteria is useful because it requires critical evaluation of the evidence present in the available data, working from the large-scale regional geology to the fine details of seismic response. It is also useful to summarize the criteria as a numerical score to facilitate comparison between different examples and different classes of ICBs and non-ICBs. Our analysis of scores of different classes of features suggests that the criteria do have some discriminatory power, but significant challenges remain.

Abstract Purpose – This paper seeks to investigate barriers faced by women in acquiring higher positions in a Malaysian multinational oil company. Design/methodology/approach – Data were obtained through a survey involving 78 executive women in the Malaysian oil company. A structured questionnaire was used to gather data. The study used gender role theory, which argues that women are viewed and treated unfavourably when they do not act according to their expected gender roles. Findings – Shows family structure and women's commitment to the family are the most significant barriers perceived by the executive women. This research reveals that women in various job positions do not differ in their perceptions with regard to barriers they face for career progression. Research limitations/implications – The study was conducted among executive women in one company only, hence it cannot be generalized to other oil companies in Malaysia. Practical implications – Provides evidence on family‐, organizational‐ and societal‐related barriers to career progression. The organization should aware of these barriers as they will affect women's professional development. Originality/value – This is a first study of this nature conducted in a large oil company which focuses on women's barriers to career progression.

Aquaculture production of crustaceans (mainly shrimp and crabs) has expanded globally, but disease outbreaks and pathogenic infections have hampered production in the last two decades. As invertebrates, crustaceans lack an adaptive immune system and mainly defend and protect themselves using their innate immune system. The immune system derives energy and metabolites from nutrients, with amino acids constituting one such source. A growing number of studies have shown that amino acids and their metabolites are involved in the activation, synthesis, proliferation, and differentiation of immune cells, as well as in the activation of immune related signaling pathways, reduction of inflammatory response and regulation of oxidative stress. Key enzymes in amino acid metabolism have also been implicated in the regulation of the immune system. Here, we reviewed the role played by amino acids and their metabolites in immune-modulation in crustaceans. Information is inferred from mammals and fish where none exists for crustaceans. Research themes are identified and the relevant research gaps highlighted for further studies.

Abstract A short‐term operational planning model for natural gas production systems can help identify a consistent operational policy that satisfies contractual rules and customer specifications. Formulating and solving such a model poses challenges due to nonlinear pressure‐flowrate relations, a multicommodity network and complex production‐sharing contracts (PSC). A production allocation model is presented that can be viewed as a contractual model superimposed on an infrastructure model. The infrastructure model incorporates nonlinear pressure‐flowrate relationships for wells and pipelines, multiple qualities of gas in the trunkline network and models of facilities. The contractual model is a mathematical representation of the PSC and associated operational rules. The model features are inspired by the Sarawak Gas Production System (SGPS) in East Malaysia. A case study similar to the Sarawak Gas Production System (SGPS) is presented. The final formulation is a nonconvex mixed‐integer nonlinear program and is solved with GAMS/BARON to global optimality. A hierarchical multiobjective operational study is also presented. © 2007 American Institute of Chemical Engineers AIChE J, 2008

Although the vast majority of higher animals are fixed for one chiral morph or another, the cause for this directionality is known in only a few cases. In snails, for example, rare individuals of the opposite coil are unable to mate with individuals of normal coil, so directionality is maintained by frequency-dependent selection. The snail subgenus Amphidromus presents an unexplained exception, because dextral (D) and sinistral (S) individuals occur sympatrically in roughly equal proportions (so-called 'antisymmetry') in most species. Here we show that in Amphidromus there is sexual selection for dimorphism, rather than selection for monomorphism. We found that matings between D and S individuals occur more frequently than expected by chance. Anatomical investigations showed that the chirality of the spermatophore and the female reproductive tract probably allow a greater fecundity in such inter-chiral matings. Computer simulation confirms that under these circumstances, sustained dimorphism is the expected outcome.

Abstract The Mega Platform is a 30- × 50-km-large and 1.2-km-thick middle Miocene carbonate platform located in the Luconia Province, offshore Sarawak, Borneo. The platform originated in the late early to early middle Miocene on a regional fault-bounded structural high, first aggraded and then backstepped during a series of third-order sea level fluctuations during the middle Miocene (TB2.3-2.6). The Jintan Platform termination with an area of 8 × 12 km is one of the prominent backsteps toward the top of the Mega Platform. Three-dimensional (3-D) seismic indicates that growth on Jintan ceased relatively early with continued carbonate aggradation in adjacent smaller terminations (M1, M1-East). Spectacular reservoir architecture and diagenesis are revealed by the seismic. Several transgressive, aggradational, and progradational cycles are overprinted by repeated karst events. Dissolution features and bank-margin collapse are aligned to a deep-seated regional fault system, which periodically became reactivated during carbonate growth. A large triangular-shaped graben formed during one of the faulting periods but subsequently healed by a prograding reef-margin sequences. Two alternative scenarios are presented to explain the ultimate demise of the platform. The first proposes drowning resulting from a combination of subsidence and eustatic sea level rise. The second evokes a much-later drowning, which was preceded by a long period of exposure resulting from a second-order sea level fall and an initial decrease in subsidence caused by the onset of tectonism in Borneo during the late Miocene. In any case, following a hiatus of about 5 m.y., the platform was finally buried by deep-marine siliciclastics that prograded into the basin from the large delta systems of northwest Borneo. Recognition of growth architecture, faulting, and karstification is a key to exploiting the hydrocarbon reservoirs of the Mega Platform. A 30-m-thick low-porosity and -permeability layer shields the gas trapped in Jintan from the underlying aquifer. Penetrated by only one well, the extent of the layer and areas of breaching caused by faulting and karstification are identified on seismic. Interpretation of the seismic is critical to assessing whether and how the underlying aquifer is felt during reservoir depletion and whether there is pressure communication between adjacent reservoirs connected via the aquifer. Cores and logs from three wells provide ground truthing of reservoir architecture, karst features, and faulting derived from the interpretation of reflection and inversion seismic. The interpretation is then imported into static and dynamic 3-D models to constrain reservoir properties, predict dynamic behavior, and guide optimum field development.

Abstract Controlled-source electromagnetic (CSEM) field surveys offer a geophysical method to discriminate between high and low hydrocarbon saturations in a potential reservoir. However, the same geological processes that create the possible hydrocarbon reservoir may also create topography and near-surface variations of resistivity (e.g., shallow gas or hydrates) that can complicate the interpretation of CSEM data. In this paper, we discuss the interpretation of such data over a thrust belt prospect in deepwater Sabah, Malaysia. We show that detailed modeling of the key scenarios can help us understand the contributions of topography, near-surface hydrates, and possible hydrocarbons at reservoir depth. Complexity at the surface and at depth requires a 3D electromagnetic modeling code that can handle realistic ten-million-cell models. This has been achieved by using an iterative solver based on a multigrid preconditioner, finite-difference approach with frequency-dependent grid adaptation.

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Purpose Given the intense competition in the hotel industry, this study investigates the effect of overwork (OW) and overtime (OT) on turnover intention (TI) as well as the moderating effect of incentives in the context of non-luxury hotels in an emerging market. Design/methodology/approach Using a purposive sampling technique, a total of 271 front-line employees who are currently working in non-luxury hotels in Sarawak responded to the study. Partial least squares structural equation modeling (PLS-SEM) was used to perform latent variable and moderation analyses. Findings The findings show that both OW and OT have a direct impact on TI. Contrary to the past studies, incentives do not exert any moderating effect on the relationship between OW, OT and TI among the employees working at non-luxury hotels. Originality/value This is one of the first studies to explore the effect of incentives between OW and working OT on TI in the context of the non-luxury hotels in an emerging market and show why incentives might not work. It further advances the understanding of the JD-R theory, demonstrating the necessity for organizations to provide matching resources to address job strains.

Understanding extreme ocean environments and their interaction with fixed and floating structures is critical for offshore and coastal design. Design contours are useful to describe the joint behavior of environmental, structural loading, and response variables. We compare different forms of design contours, using theory and simulation, and present a new method for joint estimation of contours of constant exceedance probability for a general set of variables. The method is based on a conditional extremes model from the statistics literature, motivated by asymptotic considerations. We simulate under the conditional extremes model to estimate contours of constant exceedance probability. We also use the estimated conditional extremes model to estimate other forms of design contours, including those based on the first-order reliability method (FORM), without needing to specify the functional forms of conditional dependence between variables. We demonstrate the application of new method in estimation of contours of constant exceedance probability using measured and hindcast data from the Northern North Sea, the Gulf of Mexico, and the North West Shelf of Australia, and quantify their uncertainties using a bootstrap analysis.

Research Article| July 31, 2018 The Stratigraphically Preserved Signature of Persistent Backwater Dynamics in a Large Paleodelta System: The Mungaroo Formation, North West Shelf, Australia John Martin; John Martin 1Shell International Exploration and Production, Projects and Technology, Houston, Texas 77082, U.S.A. Search for other works by this author on: GSW Google Scholar Anjali M. Fernandes; Anjali M. Fernandes 2Center for Integrative Geosciences, University of Connecticut at Storrs, Connecticut 06269, U.S.A. Search for other works by this author on: GSW Google Scholar Jennifer Pickering; Jennifer Pickering 1Shell International Exploration and Production, Projects and Technology, Houston, Texas 77082, U.S.A. Search for other works by this author on: GSW Google Scholar Nick Howes; Nick Howes 1Shell International Exploration and Production, Projects and Technology, Houston, Texas 77082, U.S.A. Search for other works by this author on: GSW Google Scholar Simon Mann; Simon Mann 3Shell Malaysia, Ltd., Kuala Lumpur, KUL 50470, Indonesia Search for other works by this author on: GSW Google Scholar Katja McNeil Katja McNeil 4Shell Australia, Ltd., Perth, WA 6000, Australia Search for other works by this author on: GSW Google Scholar Journal of Sedimentary Research (2018) 88 (7): 850–872. https://doi.org/10.2110/jsr.2018.38 Article history first online: 31 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation John Martin, Anjali M. Fernandes, Jennifer Pickering, Nick Howes, Simon Mann, Katja McNeil; The Stratigraphically Preserved Signature of Persistent Backwater Dynamics in a Large Paleodelta System: The Mungaroo Formation, North West Shelf, Australia. Journal of Sedimentary Research 2018;; 88 (7): 850–872. doi: https://doi.org/10.2110/jsr.2018.38 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract As large, deep rivers enter their coastal reaches, they are usually affected by a lengthy backwater zone. Recent studies have demonstrated pronounced geomorphic effects, such as channel deepening and decreased lateral migration rates. These observations appear to be linked to variable fluxes of sediment in rivers that characteristically vary their discharge across their backwater segments. How do such a variable sediment transport regime and its depositional effects manifest as stratigraphic architecture over geologic time? To address this question, we mapped and analyzed over 700 channel belts from a large (70,000 km2) seismic survey of the Mungaroo Formation, Northern Carnarvon Basin, Australia. Following analysis of measurements of channel-belt patterns, we propose that the Mungaroo stratigraphy was constructed by a continental-scale paleodelta and that it reveals a record of backwater-influenced deposition over a length scale of 400 km. Width measurements of the Mungaroo channel belts decay only weakly down system, in a manner similar to the lowermost reaches of the late Holocene Mississippi River, here invoked as an analogous system. In addition, significant downstream fining in the Mungaroo system is interpreted from wireline-log and lithologic core data, a trend that is also seen in the Mississippi channel belt, where bank-attached bars fine downstream due to reduced contributions of bedload. By comparing the two systems, we show that the depositional trends expressed in the 103 year record of the Mississippi River and the 106 year record of the Mungaroo paleodelta are similar, each having generated channel belts that only slightly narrow down system but transition from sand-rich to heterolithic or mud-dominated along the lower 30 to 50 percent of the backwater reach. We present a transtemporal backwater-influenced depositional model that leverages quantitative data from an analogous modern transport system for characterization of an ancient stratigraphic system. You do not currently have access to this article.

Synopsis New species of fossil crabs are described and figured from the Miocene and Pleistocene of Sabah and Sarawak. The following three genera and 20 species are new: ? Paguridae gen. et sp. nov., Raninoides morrisi, Sabahranina trushidupensis (gen. nov.), Mursia bakenuensis, Gomezinus tuberculatus (gen. nov.), Saratunus longiorbis (gen. nov.), Lupocyclus karasawai, Galene litoralis, Xanthias miocenicus, Pilumnus fookimensis, Hyastenus sp., Parthenope clypeformis, Parthenope jugula, Nucia platyspinosa, Leucosia calcarata, Pariphiculus decemtuberculatus, Pariphiculus multituberculatus, Philyra trusanensis, Bicarinocarcinus tumidus, Pinnixa microgran‐nulosa, Retropluma laurentae. Emended descriptions and/or stratigraphical and/or geographical ranges are given for the following 18 species: Thalassina anomala (Herbst), Charybdis (C.) sp., cf. Charybdis (C.) annulata (Fabricius), Heikea tuberculatum nov. com. (Morris & Collins), Podophthalmus vigil (Fabricius), Podophthalmus fusiformis Morris & Collins, Portunus obval‐latus Morris & Collins, Portunus woodwardi Morris & Collins, Cyclodius ungulatus (A. Milne Edwards), Carcinoplax sp. aff. Carcinoplax prisca Imaizumi, Hexapus decapodus (Morris & Collins), Pisoides sp., cf. Pisoides bidentatus (A. Milne Edwards), Nucilobus symmetricus Morris & Collins, Leucosia tutongensis Morris & Collins, Iphiculus sexspinosus Morris & Collins, Myra subcarinata Morris & Collins, Orthakrolophus bittneri (Morris & Collins), Macrophthalmus wilfordi Morris & Collins and Pinnixa aequipunctata Morris & Collins. As well as allowing description of new species, the material in the present collections contains species hitherto absent from the fossil record of Borneo sensu lato; the stratigraphical ranges of other species is extended.

The application of sequence stratigraphy to seismic interpretation has proven to be fundamentally important in basin analysis. It provides a framework for understanding strat-igraphic evolution and is a key element in predicting the spatial distribution of reservoir, seal, and source rocks. Traditional methods of seismic se-quence stratigraphy make use of observations such as stacking patterns, seismic character of facies, and their distribution to develop subsurface models. We present a set of seismically derived geometric attributes that enhance and characterize these observations, allowing a sequence stratigraphic framework to be developed in the earliest stages of interpretation.

ABSTRACT Miocene carbonate reservoirs in Central Luconia, offshore Sarawak, Malaysia, have been delivering gas for over 30 yr. In this paper, learnings from that period of production are used to understand the key drivers affecting flow during production and recovery optimization in existing fields as well as development decisions for new discoveries. The large data set, generated over more than 40 yr, was analyzed in a consistent manner through a holistic database, constrained by a stratigraphic framework, to allow reservoir units to be compared like-for-like (“integrated knowledge base” [IKB] concept). Carbonate reservoir heterogeneities impacting flow are grouped into “horizontal–heterogeneities”—argillaceous flooding layers and exposure-related karst—and “vertical–heterogeneities”—large-scale architectural elements, found especially along platform margins. Both types of heterogeneities control water ingress during production and influence the recovery mechanism. Argillaceous flooding layers can act as baffles, holding back water rise during production, or can form pressure compartments. Long-lived, fault-bounded reef margins, carbonate shoals, islands, and karsts can be vertical conduits for aquifer inflow. Platform shape and architecture impact column height and hence recovery efficiency. Additional drivers impacting recovery were found to be gas-column height, aquifer size and permeability, pressure connection to neighboring fields, and field development concepts. All drivers identified impact decisions throughout the field life, e.g., well count and design, intervention capabilities, evaluation and mitigation of early-water breakthrough, reservoir management, selecting enhanced recovery methods, and abandonment pressure. The IKB allowed to derive “big rules” on what matters for flow, which were used to decide on development strategies for greenfields in Central Luconia. The presented outcomes can be extrapolated to comparable carbonate systems, whereas the IKB approach can be adapted and applied to other mature basins and reservoir types where equally vast and historic data sets are awaiting to be used in the current era of digitalization.

Abstract Three activity coefficient models for electrolyte solutions were evaluated and compared. The activity coefficient models are: The electrolyte NRTL model (ElecNRTL) by Aspentech, the mixed solvent electrolyte model (MSE) by OLI Systems, and the Extended UNIQUAC model from the Technical University of Denmark (DTU). Test systems containing a single salt (NaCl), multiple salts, and mixed solvent aqueous electrolyte solutions were chosen. The performance of the activity coefficient models were compared regarding the accuracy of solid–liquid and vapor–liquid equilibrium calculations for the test systems. © 2009 American Institute of Chemical Engineers AIChE J, 2010

The Lower Palaeozoic Haima Group of the Sultanate of Oman comprises a sequence dominated by siliciclastic rocks up to several kilometres thick and broadly divisible into two groups. The sequence is known in outline from subsurface exploration, but recent field work on outcrops in the isolated Huqf area in east-central Oman has allowed a more detailed environmental interpretation of the succession. At the base coarse continental deposits of the Lower Haima Group rest unconformably on Precambrian–Lower Cambrian Huqf Group sediments (mainly carbonates and evaporites). The overlying Upper Haima Group comprises from base to top the aeolian dominated Amin Formation, the non-marine (coastal plain) to shallow marine (intertidal–subtidal) sediments of the Andam Formation, the non-marine to marginally marine Ghudun Formation, and the complex cyclical deep to shallow water deposits of the Safiq Formation. Correlation of the Haima Group of Oman with the Lower Palaeozoic of the Arabian Peninsula, North Africa and Iran allows the evolution of the Gondwanan margin to be modelled. A widespread Lower Cambrian sequence of coarse alluvium, resting on peneplained Upper Precambrian–Infracambrian Huqf Group strata, represents the final stage of uplift and basin fill associated with the Late Proterozoic suturing of Arabia and adjacent plates which resulted in the formation of the Gondwanan continent. The overlying thick sequence of continental (fluvial and aeolian) sediments was deposited in a series of stable intracratonic basins across the Gondwanan landmass. In the Mid- and Late Cambrian an overall sea-level rise led to the repeated development of shallow marine shelf carbonates across the margin. The subsequent replacement of this marginal carbonate sequence with a thick marginal to non-marine, sand dominated sequence may reflect the interplay of several events: the drift of Gondwana towards more southerly latitudes, a phase of strong tectonic rejuvenation during the latest Cambrian–Early Ordovician, and/or a eustatic fall in sea-level. Organic-rich marine mudrocks were deposited over much of the Gondwanan platform during a series of marked eustatic sea-level rises during the Mid–Late Ordovician and Early Silurian. In Oman no evidence has yet been found for the significant Late Ordovician glacial event recorded from North Africa and Saudi Arabia.