Reef complex lithofacies and reservoir, Rama field, Sunda basin, Southeast Sumatra, Indonesia

Tonkin, P. C.; Temansji, Atmawan; Park, Robert K.

doi:10.29118/ipa.259.7.1..7.32

Cited by 2 publications

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“…It formed due to mixing-zone processes with a progressive increase in marine-derived fluids. The same phase is recorded in the Rama Field (Tonkin et al 1992), where it is a minor porosity-reducing component. A third and final phase of dolomite in the Krisna Field is ferroan, forming coarse crystalline syntaxial overgrowths on existing crystals.…”

Section: Batu Raja Limestone South Sumatra Sunda and Northwest Javasupporting

confidence: 57%

“…It was derived from sulphate reduction via oxidation of organic material. In the Rama Field, Tonkin et al (1992) record dolomite crystals of 5-25 pm diameter, most commonly developed in intervals containing greater than 7-10% terrigenous mud. Here, dolomite occurs as isolated to clustered rhombs that can make up to 27% of the bulk volume.…”

Section: Batu Raja Limestone South Sumatra Sunda and Northwest Javamentioning

confidence: 99%

“…Overall, dolomite is most widely encountered as a replacive phase associated with argillaceous carbonates (Berry 1976). In formations such as the Batu Raja, Batu Putih and Vanda carbonates, it is most commonly reported in deposits containing greater than 7-10% terrigenous mud (Netherwood & Wight 1992;Tonkin et al 1992). In these argillaceous deposits dolomite occurs as microcrystallinefinely crystalline rhombs, which locally form clusters.…”

Section: Dolomite Distribution and Habitsmentioning

confidence: 99%

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Dolomites in SE Asia — varied origins and implications for hydrocarbon exploration

Carnell

Wilson

2004

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Carbonates in SE Asia range in age from Palaeozoic to Recent, but are most important as reservoirs in the Neogene where they comprise a major target for hydrocarbon exploration (e.g. Batu Raja Formation, South Sumatra, Sunda and Northwest Java basins). Carbonates of pre-Tertiary, Palaeogene and Neogene age all show a strong diagenetic overprint in which dolomite occurs as both cementing and replacive phases associated with variable reservoir quality. This paper reviews published data on the occurrence and types of dolomites in SE Asian carbonates, and considers the models that have been used to explain the distribution and origin of dolomite within these rocks.Pre-Tertiary carbonates form part of the economic basement, and are little studied and poorly understood. Although some, such as in the Manusela Formation of Seram, may form possible hydrocarbon reservoirs, most are not considered to form economic prospects. They are best known from the platform carbonates of the Ratburi and Saraburi groups. in Thailand, and the oolitic grainstones of the Manusela Formation of Seram. The Ratburi Group shows extensive dolomitization with dolomite developed as an early replacive phase and as a late-stage cement.Palaeogene carbonates are widely developed in the region and are most commonly developed as extensive foraminifera-dominated carbonate shelfal systems around the margins of Sundaland (e.g. Tampur Formation, North Sumatra Basin and Tonasa Formation, Sulawesi) and the northern margins of Australia and the Birds Head microcontinent (e.g. Faumai Formation, Salawati Basin). Locally, carbonates of this age may form hydrocarbon reservoirs. Dolomite is variably recorded in these carbonates and the Tampur Formation, for example, contains extensive xenotopic dolomite.Neogene carbonates (e.g. Peutu Formation, North Sumatra) are commonly areally restricted, reef-dominated and developed in mixed carbonate-siliciclastic systems. They most typically show a strong diagenetic overprint with leaching, recrystallization, cementation and dolomitization all widespread. Hydrocarbon reservoirs are highly productive and common in carbonates of this age. Dolomite is variably distributed and its occurrence has been related to facies, karstification, proximity to carbonate margins and faults. The distribution and origin of the dolomite has been attributed to mixing-zone dolomitization (commonly in association with karstic processes), sulphate reduction via organic matter oxidation, and dewatering from the marine mudstones that commonly envelop the carbonate build-up.Dolomite has a variable association with reservoir quality in the region, and when developed as a replacive phase tends to be associated with improved porosity and permeability characteristics. This is particularly the case where it is developed as an early fabric-retentive phase. Cementing dolomite is detrimental to reservoir quality, although the extent of this degradation generally reflects the abundance and distribution of this dolomite.Dolomitization is also inferred to have influenced the distribution of non-hydrocarbon gases. This is best documented in North Sumatra where carbon dioxide occurs in quantities ranging from 0 to 85%. There are a number of possible mechanisms for generating this CO2 (e.g. mantle degassing), although the most likely source is considered to be the widely dolomitized Eocene Tampur Formation that forms effective basement for much of the basin. High heat flows are suggested to have resulted in the thermogenic decomposition of dolomite with CO2 produced as a by-product.

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Section: Batu Raja Limestone South Sumatra Sunda and Northwest Javasupporting

confidence: 57%

Section: Batu Raja Limestone South Sumatra Sunda and Northwest Javamentioning

confidence: 99%

Section: Dolomite Distribution and Habitsmentioning

confidence: 99%

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Dolomites in SE Asia — varied origins and implications for hydrocarbon exploration

Carnell

Wilson

2004

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A Review of Dolomites in Southeast Asia

Carnell¹,

Wilson²

Proc. Indon Petrol. Assoc., 29th Ann. Conv.

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Reef complex lithofacies and reservoir, Rama field, Sunda basin, Southeast Sumatra, Indonesia

Cited by 2 publications

References 0 publications

Dolomites in SE Asia — varied origins and implications for hydrocarbon exploration

Dolomites in SE Asia — varied origins and implications for hydrocarbon exploration

A Review of Dolomites in Southeast Asia

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