Offshore Sarawak Research Articles

日本石油開発（株）のガス田開発事業

Nippon Oil Exploration Ltd. (NOEX), a subsidiary of Nippon Mitsubishi Oil Company, participates up-stream business in 11 countries with 20 oil and gas E & P projects, where NOEX has the role of operator in Malaysia, Vietnam, Australia and the United States. NOEX is involved in several gas projects in South East Asia, Australia and the United States. In general, gas field development could be commercialized on the condition that gas markets are large enough to commit long-term gas supply. Transportation method of produced gas from field sites to markets today is limited only to either pipeline or LNG tankers. These limitations restrict to make a profit in a short time, specially on these gas fields located in remote area from markets, even for bigger size of reserves. Most of NOEX gas development projects are being carried out by conventional methods, with the exception of newly discovered gas field in Australia, where early economical development is sought with the application of new technology. In this paper, five NOEX gas projects are introduced from the viewpoints of three different development types, such as pipeline, LNG and new technology.Yetagun gas field, which was discovered in 1992, offshore Andaman Sea in Myanmar, started gas production in May 2000 to export gas to Thailand through pipeline. Another gas pipeline project has been planned in Papua New Guinea to utilize oil fields' associated gas to Australian market. Gas fields in offshore Sarawak, Malaysia discovered in 1990 through 1994 are under development to feed source gas to MLNG-3 plant, which is also under construction in Bintulu, Sarawak. Planned start-up date of gas production is October 2003. Tangguh LNG project in Indonesia is also in progress, however, difficulties of finding new customers in saturated Asian gas market cause prolongation of project schedule.In May 2000, new gas reserves were discovered by drilling NOEX's exploration well Crux-1 in AC/P23 licensed area in Timor Sea, West Australia. Longer distance to the shore market and middle size of the reserves may prevent the early development of Crux gas field in case conventional approach is implemented. Application of Gas to Liquid (GTL) technology may be the most realistic alternative for Crux development under today's saturated LNG market, small domestic market and global environmental requirement. Under these circumstances, NOEX has started a feasibility study of GTL applicability to Crux gas field to make a profit as early as possible. Once GTL technology becomes viable both technically and economically, NOEX's strategy to gas resources would be changed to more aggressive direction.

ABSTRACT: Assessing the impact of reservoir architecture, faulting and karst on the performance of a Middle Miocene carbonate reservoir, offshore Sarawak using 3D modelling techniques

ABSTRACT: Assessing the impact of reservoir architecture, faulting and karst on the performance of a Middle Miocene carbonate reservoir, offshore Sarawak using 3D modelling techniques

ABSTRACT: Integrated Subsurface modelling of a Miocene reefal buildup, offshore Sarawak, Malaysia

ABSTRACT: Integrated Subsurface modelling of a Miocene reefal buildup, offshore Sarawak, Malaysia

Implementation of Twin-Well Technology Offshore Sarawak

This article is a synopsis of paper SPE 50082, "Implementation of 'Twin-Well' Technology Offshore Sarawak," by S. Hashim, T. Runggai, M.Z. Khalid, W. Kruit, D. Short, B. Duncan, N. Pauzi, J. Haron, and F.N. Low, Petronas Carigali Sdn. Bhd., originally presented at the 1998 SPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, 12-14 October.

Three dimensional reservoir geological model and multiple scenario volumetrics of the F23 Miocene carbonate buildup, Luconia Province, offshore Sarawak

Typically, the geology and production behavior of gas reservoirs in the atoll shaped Miocene carbonate structures of the Central Luconia province, offshore Sarawak, are best constrained in the center of the field due to a biased distribution of wells. Control over the reservoir architecture, pore volume and fluid flow behavior decrease significantly towards the reservoir flanks introducing uncertainties for an optimized reservoir management. An integrated reservoir geological study was initiated with the objective to decrease uncertainties and increase the understanding of their impact on static and dynamic reservoir models. Data from an integrated core, seismic and petrophysical evaluation, including lateral seismic porosity prediction and the application of geostatistics, were combined to a 3-D fully computerized reservoir model. The core and seismic evaluation reveals a complex internal reservoir architecture strongly influenced by paleo-wind pattern and sea-level fluctuations with backstepping, progradational and aggradational growth phases. Transgressive systems tracts are represented by dense argillaceous limestones, which form more or less continuous blankets possibly isolating gas volumes and influencing vertical water movement. During repeated periods of flooding the platform back-stepped up-wind only to prograde down-wind again during sea-level high stands until re-reaching the previous platform margin. An uncertainty tree was constructed for the F23 field in order to assess the impact of combined and individual uncertainties on static and dynamic reservoir models. Parameters considered in the uncertainty tree are the top carbonate structure, the porosity distribution, the hydrocarbon saturation and the gas expansion factor. Most likely, low and high cases were used in order to assess the parameters with the most impact on the uncertainty of hydrocarbon volume and fluid flow, in particular possible flank water encroachment. Results from the volumetric calculations arrive at a most likely GIIP close to that derived from material balance analysis. However, low and high cases significantly exceed the uncertainty range of the material balance GIIP. While the geology of the reservoir flank is now better constrained using refined seismic interpretations, uncertainties in these areas remain high.

Miocene carbonates of the Luconia province, offshore Sarawak: implications for regional geology and reservoir properties from Strontium-isotope stratigraphy

The Luconia Province, offshore Sarawak, Malaysia, is one of the largest SE-Asian carbonate provinces with more than 200 platforms and gas reserves exceeding 40 Tscf. The application of the Sr­ isotope technique integrated with core, log and seismic data significantly refines the stratigraphy of the province despite extensive diagenetic alteration. Based on the new data, a unified concept of platform evolution is tied to global sea-level variations and the regional distribution of reservoir architecture. Evidence is presented for major karstification during and after platform growth and its influence on the regional distribution of reservoir properties. Sr-isotope analyses (ntotaJ = 137; data range: O.7084~.70903 for NBS987 = 0.710230) suggest that the carbonate platforms of the Luconia province are Early to Middle Miocene in age. The Sr-isotope signature is apparently unaffected by diagenetic stabilization from metastable carbonates to low-Mg calcite while dolomitization caused alteration of the isotope ratio. Growth and demise of the province can be correlated with a second-order eustatic sea-level cycle (TB2). Major karst horizons and flooding, aggradation and progradation packages are linked via step-changes in isotope signature to third order eustatic sea-level fluctuations. Simultaneous with the second order sea-level drop (late Middle Miocene) the influx of siliciclastics split the province into a southern part with low relief carbonate banks and a northern part with high relief platforms. All growth terminated at the end of the Middle Miocene. Low relief banks were buried while high relief platforms were karstified prior to drowning (Late Miocene­ Pliocene). The regional distribution of pore types, porosity and permeability is linked to the duration of exposure and burial diagenesis. In the karstified platforms of the northern part drilling losses are common.

The tectonic evolution and associated sedimentation history of Sarawak Basin, eastern Malaysia: a guide for future hydrocarbon exploration

Abstract A seismic-stratigraphic study of the reprocessed regional lines for the offshore Sarawak area was undertaken with the aim of reviewing the present understanding of the tectonics and the palaeo-depositional environments of the Sarawak Basin. The study was integrated with biostratigraphy and wireline-log data from the wells drilled throughout the basin. Seven unconformities were identified within the Tertiary sediments and these were used as the markers for the seismic correlations. Where the unconformities become conformable, well data were used to guide the correlation of the conformities. Palaeo-environment maps were generated which document the interaction of tectonics and sediments throughout the basin history. The development of the Sarawak Basin commenced in late Oligocene times with deposition along a coastline running in a NW-SE direction, which is almost perpendicular to the present-day coastline. The coastline was oriented to the present-day NE-SW during late Miocene times. Geochemistry of Sarawak Basin oils shows generation of hydrocarbons from land plant dominated source rocks. The distribution of these types of source rocks are favoured in the Coastal Fluvial, Coastal and Lower Coastal Plain environments. The quantity and quality of the source rocks deteriorates with the distance from the coastline. The palaeo-environment maps illustrate the likely distribution of Sarawak Basin source rocks which will help in effectively planning for future exploration in Sarawak. The study also revealed that the Sarawak Basin was formed as a result of NW-SE-trending right-lateral fault movement during late Oligo-Miocene times. This dextral movement was responsible for creating the NW-SE coastline and divided the offshore Sarawak area into two sub-basins. Deposition and preservation of coastal plain and shallow marine sediments continued in the eastern area while the western area remained as a ‘high’ until late Miocene times. The dextral strike-slip movement which controlled the evolution of the Sarawak Basin is sub-parallel to a number of lineaments elsewhere in Sarawak. The timing of movement of these suggests progressive younging in an eastward direction. It is also believed the late structuration of the sediments and the formation of structural traps is linked to these tectonic movements.

Tukau Field: Finding New Oil in Matured And Complex Field After 20 Years of Production: ABSTRACT

The Tukau Field is located some 30 km offshore Sarawak, Malaysia. in water depth of about 160 ft. The field, discovered by TK-2 in 1966 found 235 ft net oil sand and 16 ft wet gas sand. After further seismic data acquisition and interpretation, six (6) appraisal wells were drilled from 1973 to 1975 before the field could be commercially developed. The Tukau structure is a structurally complex feature formed as a domal anticlinal uplift, located along the Tukau I Bakau / Baram trend. It is dissected at the shallow level by normal synthetic and antithetic faults. These fault system divide the field into seven (7) fault blocks. The major hydrocarbon accumulations are between 2400 ftss and 7500 ftss and the main prospective sequence consists of fine to very fine grained sand of the upper cycle V of late Miocene age and deposited in a deltaic, fluviomarine, coastal to near shore environment. Development drilling commenced in 1975 with a total of 23 wells. To date a total of nine (9) rounds of development activities were carried out resulting in 55 wells being drilled and nine (9) well jackets installed. In 1975, based on the seismic and well data. the fieldmore » is estimated to contain some 300 MMSTB of oil. Following subsequent field reviews Incorporating some 50 odd well data and seismic reinterpretation in 1987. the field STOIIP increased to 500 MMST. 3D seismic was acquired in 1992 and field review carried out In 1995 resulted In some development potential and appraisal / exploration opportunities. The appraisal well drilled in October 1995, increased the field STOIIP by some 50 MMSTB. Preliminary evaluation based on geological, engineering and economic information indicated that Tukau field will be further developed with additional well jacket and this will boost the field production by about 50%.« less

Geological Factors Controlling Gas Volumes in Miocene Carbonate Buildups - Offshore Sarawak: ABSTRACT

Over 170 independent Miocene carbonate buildups are located within the Luconia Province of offshore Sarawak, Malaysia. They vary in size and shape from small isolated pinnacles through tabular to broad low relief platforms, distributed across nearly 10MM acres of the shallow Miocene shelf. Among the 70-odd buildups drilled to date, over half are gas-bearing. Discovered volumes exceeds 40 TCF of gas-in-place, with gas columns ranging from a few meters to greater than 500 m. Geological factors suspected of controlling the occurrence and volume of gas within each buildup include caprock, source, stratigraphic and structural variables. The source for gas is the (largely uncontrolled) Cycle I/II coastal plain sequence. In practice, only caprock and seismically-derived stratigraphic and structural factors provide sufficient geological/geophysical evidence to characterize and distinguish buildups at the prospect level. Useful caprock-related discriminators include clastictseismic facies, drape, and pore pressure - each reflecting the sealing capacity of the caprock as measured by the gas column height in the reservoir. Factors related to the gas-focusing effectiveness of bedding below the reservoir include the relief and structural configuration of the pre-carbonate section, the areal extent of the drainage area, and faulting. As prospect discriminators, these structural factors are limited by possiblemore » velocity distortions and poor seismic resolution beneath the carbonate section. Five gas accumulations discovered by Occidental since 1992 are compared to show the variety of discernible factors controlling their in-place volumes.« less

Genesis of siderite in the Upper Miocene offshore Sarawak: constraints on pore fluid chemistry and diagenetic history

The cored sequence of the upper Miocene reservoir of Baram field, offshore Sarawak, consists of cyclic quartz-rich sandstones and mudstones interpreted to have been deposited during storm events in shallow to midshelfwater depths. The sequence is intercalated with minor tidal intervals. Authigenic siderite is common in sandstones throughout the sequence. Siderite cemented zones are up to 2 m thick. The cement is found in five different sandstone types: laminated sandstone, massive sandstone, bioturbated sandstone, heterogeneous sandstone, and in association with mud intraclasts and shell fragments horizon. Whole-rock XRD gives estimate of 20 to 40% of siderite in bioturbated and heterogeneous sandstones and 10 to 25% for the others. Petrographic analysis reveals that diagenetic siderite occurs in four different crystal morphologies: rhombic, bundle, acicular and cylindrical. The rhombic siderite, which commonly occurs in bioturbated and heterogeneous sandstone, has the most adverse effect on the poroperm characteristics of the sandstones, reducing porosity to 10% and permeability to 2 md. Bl3C and BIBO plots show groupings based on morphology. Bundled and acicular siderite show ranges of Bl3CpDB of -15 to -25 and BIBOpDB of 0 to -1. The late Miocene seawater BIBO estimate for the region is -O.S PDB. This would give the bundle and acicular siderite a temperature of formation range of 25° to 30°C. The Bl80 values are compatible with precipitation at shallow burial depth from unaltered sea­ water; Bl3C values are inherited from sulfate reduction horizons. Rhombic siderite has ranges of Bl3CpDB of -5 to -15 and Bl80pDB of -3 to -4. The range of Bl3C indicates that siderite diagenesis occurred within both the shallow sulfate reduction zone and at deeper levels within the zone of decarboxylation. The maximum temperature of formation here is 3So to 4SoC at depths of about -450 to -SOO m, assuming precipitation from unaltered seawater. These results are consistent with those ofICP geochemical values which indicate that the rhombic siderite are Mg-rich relative to the acicular and bundle types. The cylindrical siderite shows isotope values between these two extremes. These results reveal the pathways of early pore water evolution and diagenetic history of the Upper Miocene succession of Baram Field.

FMS/FMI Borehole Imaging of Carbonate Gas Reservoirs, Central Luconia Province, Offshore Sarawak, Malaysia: ABSTRACT

The Central Luconia Province, offshore Sarawak, is a significant gas province characterized by extensive development of late Miocene carbonate buildups. Some 200 carbonate structures have been seismically mapped of which 70 have been drilled. FMS/FMI borehole images were obtained from three appraisal wells drilled in the [open quotes]M[close quotes] cluster gas fields situated in the northwestern part of the province. The [open quotes]M[close quotes] cluster fields are currently part of an upstream gas development project to supply liquefied natural gas. Log facies recognition within these carbonate gas reservoirs is problematic due mainly to the large gas effect. This problem is being addressed by (1) application of neural network techniques and (2) using borehole imaging tools. Cores obtained from the M1, M3, and M4 gas fields were calibrated with the FMS/FMI images. Reservoir characterization was obtained at two different scales. The larger scale (i.e., 1:40 and 1:200) involved static normalized images where the vertical stacking pattern was observed based on recognition of bed boundaries. In addition, the greater vertical resolution of the FMS/FMI images allowed recognition of thin beds. For recognition of specific lithofacies, dynamically normalized images were used to highlight lithofacies-specific sedimentary features, e.g., clay seams/stylolites, vugs, and breccia zones.more » In general, the FMS/FMI images allowed (1) easier recognition of reservoir features, e.g., bed boundaries, and (2) distinction between lithofacies that are difficult to characterize on conventional wireline logs.« less

Horizontal Well Application for Development of a Thin Oil Column Within Multiple Discontinuous Lower Coastal Plain Sand Units, Lower Miocene Cycle II, Offshore Sarawak, East Malaysia: ABSTRACT

The Balingian province, offshore Sarawak, holds multiple challenges to economic oil-field development. Discontinuous primary gross geometries of the lower coastal plain objective sand bodies and a strong structural overprint can combine to isolate hydrocarbon accumulations and make drainage planning difficult. The case of north Bayan development from BYDP-C illustrates these difficulties. Initial development by conventional wells encountered irregular sand distribution and thinner oil columns than expected from appraisal well drilling. The latter part of the campaign used dip-oriented horizontal completions of between 2000 and 3000 ft to salvage development of a 45 to 69 ft oil accumulation within the S7 sands. The benefits of horizontal well trajectory to exploit this reservoir geometry are many. The gently dipping structure, constant fluid contacts, and dip orientation of the well path allowed intersection of multiple sand units while remaining consistently positioned at the optimum location relative to the OWC and GOC. The effect of lateral sand thickness and quality variations is minimized by the relationship of the well bore to the reservoir geometry. Each sand unit is gradually penetrated from the base to the top, maximizing the opportunity for a well-developed genetic unit to be traversed. Attempts to characterize lateral relationships such asmore » sand continuity and amalgamation using discreet data from exploratory, appraisal, and conventional wells are generally non-unique and poorly predictive. Horizontal wells maximize potential contact with objective reservoirs and production potential amidst rapid sand-body thickness change and local discontinuities.« less

Genesis of Siderite in the Upper Miocene, Offshore Sarawak: Constraints on Pore Fluid Chemistry and Diagenetic History: ABSTRACT

The cored sequence of the Upper Miocene reservoir of Baram field, offshore Sarawak, consists of cyclic deltaic-related quartz-rich sandstones and mudstones interpreted to have been deposited during storm events in shallow to midshelf water depths. The sequence is intercalated with minor tidal intervals. Authigenic siderite is common in sandstones throughout the sequence. Siderite cemented zones are up to 2 m thick. The cement is found in four different sandstone types: laminated sandstone, massive sandstone, bioturbated sandstone, and in association with shell fragments. Whole-rock XRD gives estimates of 20 to 40% siderite in bioturbated sandstones and 10 to 25% for the others. Petrographic analysis reveals that diagenetic siderite occurs in four different crystal morphologies: rhombic, [open quotes]bundles,[close quotes] acicular, and cylindrical. The rhombic siderite, which commonly occurs in bioturbated sandstone, has the most adverse effect on the poroperm characteristics of the sandstones, reducing porosity to 10% and permeability to 2 md. [sigma][sup 13]C and [sigma][sup 18]O plots show groupings based on morphology. Bundled and acicular siderite show ranges of [sigma][sup 13]C[sub PDB] of [minus]15 to [minus]25 and [sigma][sup 18]O[sub PDB] of 0 to [minus]1. The late Miocene seawater [sigma][sup 18]O estimate for the region is [minus]0.8 PDB. This would give themore » bundles/acicular siderite a temperature of formation range of 26[degrees] to 30[degrees]C. The [sigma][sup 18]O values are compatible with precipitation at shallow burial depth from unaltered seawater; [sigma][sup 13]C values are inherited from sulfate reduction horizons. Rhombic siderite has ranges of [sigma][sup 13]C[sub PDB] of [minus]5 to [minus]15 and [sigma][sup 18]O[sub PDB] of [minus]3 to [minus]4. The range of [sigma][sup 13]C indicates that siderite diagenesis occurred within both the shallow sulfate reduction zone and at deeper levels within the zone of decarboxylation.« less

Overpressures in the Baram Field, Offshore Sarawak, East Malaysia: ABSTRACT

Overpressures in the Baram Field, Offshore Sarawak, East Malaysia: ABSTRACT

Neural Networks: Prediction of Carbonate Lithology and Permeability from Wireline Logs in a Miocene Buildup, Offshore Sarawak: ABSTRACT

A gas-bearing Miocene carbonate field is used as a case study to demonstrate the impact of neural network technology (nonlinear complex-pattern recognition) in carbonate reservoir modeling. In the Sarawak Miocene buildups, as in many carbonate reservoirs, most porosity is of diagenetic origin, and poroperm character is determined by dominant pore type (i.e., moldic, intergranular, intercrystalline). A fundamental prerequisite to modeling geometries of depositional/diagenetic bodies in 3-D is the ability to recognize these lithofacies (and their permeability values) from wireline logs in wells where core is unavailable; a task that has often proved elusive, as in this case, using conventional programming techniques. Neural networks appear to have solved these problems by their ability to [open quotes]learn[close quotes] the relationship between the core-defined lithofacies and permeability measurements from conventional petrophysical log suites. Neural networks can recognize nonlinear relationships, and they do not rely on predefined algorithms, thereby avoiding the limitation of fitting scattered data to linear trends. On this Miocene training set, lithofacies classifications were [open quotes]learnt[close quotes] to an accuracy of over 90%. The neural network solution for permeability prediction from logs halved the root-mean square error of the predictions obtained by conventional techniques. These results were obtained using standard logmore » suites, making the technique especially suited to field reviews and regional studies. Application of the trained networks to log suites of noncored wells in the field gives geological control by providing lithology and permeability profiles. This allows detailed interwell correlation of diagenetic rock types and their lateral porosity-permeability trends, forming the basis for 3-D reservoir modeling.« less

Multidiscipline Studies of the Depletion Behavior of the F23 Gas Field, Offshore Sarawak, East Malaysia: ABSTRACT

The F23 gas field is located 178 km north-northwest of Bintulu in the central Luconia province, offshore Sarawak. The accumulation consists of a late Miocene layered platform-type carbonate buildup 22 km[sup 2] and a maximum gas thickness of over 1000 ft. Eleven development wells and one observation well were completed in 1983, with initial gas delivery to Malaysia LNG in October 1983. Annual TDT surveys are conducted in the observation well to monitor the movement of the GWC in the central area of the field. As of April 1992, a cumulative rise of 25 ft was observed. This contrasts with material balance calculations predicted rise of some 60 ft based on Sgr of 50% inferred from core measurements. Among the potential explanations were irregular bottom-water encroachment, preferential flank water advance, or larger GIIP. As all had potentially important consequences to depletion strategy and ultimate reserves, multidiscipline studies were initiated. Time-lapse seismic data were used to better determine the existing fluid levels across the field and reservoir simulation studies were used to match observation well data and predict future reservoir behavior. Concurrent reservoir and simulation studies suggested that the material balance and observation well data could be reconciled by (1) amore » reduced aquifer, and/or increased GIIP, and/or a lower residual gas saturation, or (2) preferential flank water influx due to internal low-permeability layers. As (1) would not lead to early water breakthrough, the simulation effort was aimed to investigate (2), the possibility and implications of early edge water breakthrough via the flank zone.« less

Reservoir Geology of the F6 Field, Offshore Sarawak, Malaysia: ABSTRACT

Reservoir Geology of the F6 Field, Offshore Sarawak, Malaysia: ABSTRACT

The Role of Seismic in Exploration of Carbonate Buildups in Offshore Sarawak, Malaysia: ABSTRACT

The Luconia geological province offshore Sarawak is typical in that carbonates extensively developed mainly during the Miocene, and some 200 carbonate buildups have been seismically mapped. The seismic data of the early days were mainly used to define the carbonate structure. The present advancement of the seismic technology enables interpreters to confidently map the Miocene carbonate buildups and the Pliocene argillaceous top seals, which are characterized by low amplitude and monotonous reflectors. Furthermore, these high-frequency seismic data permit the identification of the pre-carbonate structural focusing and deep faults as hydrocarbon mitigation pathways, upper Miocene sandy thief beds, and intraformational shale as secondary top seal. The use of seismic data in the development of carbonate gas fields is not only confined to structural mapping but also to the stratigraphic interpretations. Both the vertical and lateral porosity variations of the carbonate reservoirs can be calibrated to seismic amplitude and acoustic impedance. The thickness of the reservoir indicates some relationships with the seismic isochron values. These techniques can be used in selecting optimum location for development wells.

Reservoir Geological Modeling of the A3/A6.0 Viscous Crude Reservoirs of Bokor Field, Offshore Sarawak, East Malaysia: ABSTRACT

The late Miocene A3.0/A6.0 sequence (1940-2440 ft ss), comprising four separate reservoirs, is the most prolific unit in Bokor field, with 155 MMstb of oil in place. A detailed geological modeling study was conducted in support of numerical simulation to improve understanding of the reservoir fluid flow in this viscous crude reservoir (oil gravity 19.5 API, average viscosity 10 cP). Six lithofacies were identified from 323 feet of core: poorly stratified, cross-laminated and bioturbated sandstone, sand- and mud-dominated heterolithic and mudstone. These facies represent deposition by a fluvial-dominated delta complex, which prograded into a muddy marine shelf. Based on reservoir property characterization, the facies were grouped into three reservoir flow units: Good ([theta] = 35-40%, k = 1000-2000 md), moderate ([theta] = 30-35%, k = 100-300 md), and poor ([theta] <25%, k <10 md), with mudstones acting as interreservoir seals. These flow units were then determined in 40 uncored wells using a reference set of electrofacies derived from deterministic values of GR/FDC/CNL logs integrated with the core data. This resulted in a detailed nineteen-layered reservoir model. Special emphasis was given to the identification and delineation of heterogeneities, ranging from shale intercalations to dolomite-cemented stringers. The flow-unit properties were computer mappedmore » and used in reservoir simulation models, which have yielded a good history match. Results of the study have significantly improved understanding of the reservoir fluid flow and led to identification of further infill development opportunities.« less

Oil Development in the Structurally Complex West Bayan Field, Offshore Sarawak, East Malaysia: ABSTRACT

The West Bayan structure at the prospective level is a complex east-northeast-west-southwest-striking asymmetrical anticline, dissected by mainly south-hading normal faults of varying throw. The faults are considered to have a component of strike-slip movement, which results in rapid variability of the apparent fault throw along strike. Structurally, the West Bayan can be divided into four main fault blocks. Hydrocarbons are present in a stacked series of mainly lower coastal plain deposits. This paper focuses on the S3.8, a major reservoir within the middle Miocene accumulations. The initial development of the S3.8 reservoir commenced in early 1984 with the drilling of four wells in Block 1. Three-dimensional seismic data were acquired over Bayan in 1986, and interpretation led to some changes in structural configuration. In 1989, five more development wells were drilled from a second drilling structure and completed on the S3.8 reservoir in Block 4.