Secondary Porosity Generation During Deep Burial Associated with Overpressure Leak-Off: Fulmar Formation, United Kingdom Central Graben

Hasze, None M. Wilkinson, D. Darby, R. S.

doi:10.1306/522b484d-1727-11d7-8645000102c1865d

Cited by 12 publications

(4 citation statements)

References 20 publications

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“…Based on material equilibrium, the most effective dissolution for enhancing net porosity is therefore expected in sandstones which are exposed to a geochemically open system and can freely discharge by-products and authigenic minerals (Nedkvitne and Bjørlykke, 1992). With the sealed effect by overpressure, the diagenetic environment is generally considered to be a geochemically closed system and removing large quantities of solute become extreme difficulty (Wilkinson et al, 1997). The hydraulic fracture was demonstrated to be a pressure leak-off point in the overpressure strata of the Central Graben in the North Sea, from which the fluid could migrate through the top seal (Wilkinson et al, 1997).…”

Section: Multi-phase Cementation and Dissolution In Diverse Diageneti...mentioning

confidence: 99%

“…With the sealed effect by overpressure, the diagenetic environment is generally considered to be a geochemically closed system and removing large quantities of solute become extreme difficulty (Wilkinson et al, 1997). The hydraulic fracture was demonstrated to be a pressure leak-off point in the overpressure strata of the Central Graben in the North Sea, from which the fluid could migrate through the top seal (Wilkinson et al, 1997). The leak-off point induced an open system and allowed dissolution products to migrate dynamically, which was beneficial to enhance secondary porosity (Wilkinson et al, 1997).…”

Section: Multi-phase Cementation and Dissolution In Diverse Diageneti...mentioning

confidence: 99%

“…The hydraulic fracture was demonstrated to be a pressure leak-off point in the overpressure strata of the Central Graben in the North Sea, from which the fluid could migrate through the top seal (Wilkinson et al, 1997). The leak-off point induced an open system and allowed dissolution products to migrate dynamically, which was beneficial to enhance secondary porosity (Wilkinson et al, 1997).…”

Section: Multi-phase Cementation and Dissolution In Diverse Diageneti...mentioning

confidence: 99%

“…The opinion of reducing vertical effective stress (VES) toward intergranular and cement-grain contacts by overpressure is generally accepted, which plays a significant role in primary porosity preservation and subsequently results in anomalously high porosity in deeply buried reservoirs (Osborne and Swarbrick, 1999;Bloch et al, 2002;Tingay et al, 2009;Sathar and Jones, 2016;Li, 2021). Furthermore, considerable studies indicate that overpressure has a non-ignorable influence on several diagenetic aspects mainly as follow: protecting dissolved porosities (Taylor et al, 2015;Zhang et al, 2020;Wang and Wang, 2021), indirectly controlling dissolution efficiency of organic acids and CO 2 (Jansa and Noguera Urrea, 1990;Wilkinson et al, 1997;Duan et al, 2018), retarding clay minerals transformation (Colten-Bradley, 1987;Meng et al, 2012), and affecting cementation intensity such as quartz overgrowth and carbonate cements (Osborne and Swarbrick, 1999;Bloch et al, 2002;Duan et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Effect of Diagenesis on the Quality of Sandstone Reservoirs Exposed to High-Temperature, Overpressure, and CO2-Charging Conditions: A Case Study of Upper Miocene Huangliu Sandstones of Dongfang District, Yinggehai Basin, South China Sea

Zhang

et al. 2022

Front. Earth Sci.

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The Upper Miocene Huangliu sandstones of the Dongfang district are currently regarded as an important exploration target in the Yinggehai Basin. Affected by the anomalous diagenetic environments of high temperature, overpressure, and CO2 fillings, the diagenetic evolution of the Huangliu sandstones appear complicated characteristics and subsequently exert a significant influence on reservoir development. Integrated methods employed in this study include an electron microscope, cathode luminescence, X-ray diffraction, scanning electron microscope, electron microprobe, stable isotope analysis, homogenization temperature, and physical property tests. By the comparative researches between the AF-1 and AF-2 areas of the Dongfang district, the aim of this study is to investigate the complex diagenetic modifications and their controlling effects on reservoir quality and development mechanism. With similar sedimentary features, the reservoirs in the AF-1 area exhibit slightly higher porosity than those of the AF-2 area. The permeability in the AF-1 area shows one or two orders of magnitude lower than that of the AF-2 area, and throats size distribution act as a critical factor to cause distinct diversities of permeability. In the AF-1 area, the later appearance of overpressure contributed to stronger compaction intensity and more loss of primary porosity. The dissolution induced by CO2-rich thermal fluids in late stage enhanced the secondary porosity significantly and improved the total porosity. However, extensive dissolution cause abundant precipitation including carbonate cement and authigenic illite in a closed diagenetic system, which lead to the decrease of reservoirs’ permeability. As for the AF-2 area, earlier occurrence of overpressure restrained mechanical compaction obviously and further retarded corrosion of organic acid, which preserved high proportions of primary porosity. Due to lesser impact by CO2 filling, the AF-2 area had a poor intensity of dissolution and cementation, and the authigenic illitization was also restrained significantly, which effectively prevented heavy damage on reservoir quality, and especially for permeability. Based on the diagenetic evolution pathways, two types of porosity evolution patterns are established. The effect degree on diagenesis by high temperature, overpressure, and CO2 filling vary significantly between the AF-1 and AF-2 areas. The two areas show different pathways of diagenetic evolution, forming two development patterns and exhibiting different reservoir types.

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Section: Multi-phase Cementation and Dissolution In Diverse Diageneti...mentioning

confidence: 99%

Section: Multi-phase Cementation and Dissolution In Diverse Diageneti...mentioning

confidence: 99%

Section: Multi-phase Cementation and Dissolution In Diverse Diageneti...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Diagenesis on the Quality of Sandstone Reservoirs Exposed to High-Temperature, Overpressure, and CO2-Charging Conditions: A Case Study of Upper Miocene Huangliu Sandstones of Dongfang District, Yinggehai Basin, South China Sea

Zhang

et al. 2022

Front. Earth Sci.

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Diagenetic Control of Reservoir Performance and Its Implications for Reservoir Prediction in Jinci Sandstone of Upper Carboniferous in the Middle East Ordos Basin

Guo

Qing

et al. 2022

ACS Omega

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The Upper Carboniferous sandstone reservoir is a vital replacement area for natural gas exploration in Ordos Basin. In this study, 157 Jinci sandstone samples were selected to conduct a series of experiments and analyses. The reservoir material composition and pore structure analysis shows that the lithology of the reservoir is mainly quartz arenite, followed by sublithic arenite. The detrital particles are mainly quartz (69–97.5%), followed by rock fragments (0.1–24.5%), and the content of feldspar is less than 0.01%. The cement consists of siliceous material, clay minerals, and carbonate, with averages of 2.34, 5.96, and 1.81%, respectively. Three types of pore-throat structures (HPMI curve: types 1, 2, and 3) are identified in the Jinci sandstone reservoir, corresponding to different pore-throat radius distributions (RCP curves: types A, B, and C). The study of the factors affecting reservoir pore structure and its internal mechanism shows that the reservoir pore-throat combination, affecting the reservoir performance, is mainly controlled by deposit composition and the subsquent diagenetic modification. A higher rigid particle content and an appropriate amount of siliceous cementation (2–10%) would lead to resistance of the compaction, in favor of the preservation of primary intergranular pores. When the content of ductile particles is more than 3%, the original intergranular pores tend to be substantially reduced. The deposit composition of sandstone controls the preservation of residual intergranular pores by affecting the intensity of compaction and dissolution controlling the amount and type of cementation. Compared with dissolution-subjected quartz arenites, the sublithic arenites are characterized by a common occurrence of altered kaolinite and recrystallized illite, which would destroy the reservoir property. The early diagenetic carbonate cementation, as well as the strong siliceous cementation in “sedimentary quartz arenite”, are unfavorable to the formation of high-quality reservoirs. Then, on the basis of the characteristics of various diagenesis and their interaction and internal relationship, the diagenetic sequence and diagenetic-pore evolution patterns of different types of reservoirs were established. Finally, according to the lithological characteristics and the diagenetic-controlled pore-throat evolution patterns of different types of reservoirs, the reservoir quality in the study area was predicted.

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Disseminated ‘jigsaw piece’ dolomite in Upper Jurassic shelf sandstones, Central North Sea: an example of cement growth during bioturbation?

et al. 2000

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Unusual textural and chemical characteristics of disseminated dolomite inUpper Jurassic shelf sediments of the North Sea have provided the basis for a proposed new interpretation of early diagenetic dolomite authigenesis in highly bioturbated marine sandstones. The dolomite is present throughout the Franklin Sandstone Formation of the Franklin and Elgin Fields as discrete, non-ferroan, generally unzoned, subhedral to highly anhedral`jigsaw piece' crystals. These are of a similar size to the detrital silicate grains and typically account for »5% of the rock volume. The dolomite crystals are never seen to form polycrystalline aggregates or concretions, or ever to envelop the adjacent silicate grains. They are uniformly dispersed throughout the sandstones, irrespective of detrital grain size or clay content. Dolomite authigenesis predated all the other signi®cant diagenetic events visible in thin section. The dolomite is overgrown by late diagenetic ankerite, and bulk samples display stable isotope compositions that lie on a mixing trend between these components. Extrapolation of this trend suggests that the dolomite has nearmarine d18 O values and low, positive d 13C values. The unusual textural and chemical characteristics of this dolomite can all be reconciled if it formed in the near-surface zone of active bioturbation. Sea water provided a plentiful reservoir of Mg and a pore¯uid of regionally consistent d 18 O. Labile bioclastic debris (e.g. aragonite, Mg-calcite) supplied isotopically positive carbon to the pore¯uids during shallow-burial dissolution. Such dissolution took place in response to the ambient`calcite sea' conditions, but may have been catalysed by organic matter oxidation reactions. Bioturbation not only ensured that the dissolving carbonate was dispersed throughout the sandstones, but also prohibited coalescence of the dolomite crystals and consequent cementation of the grain framework. Continued exchange of Mg 2+ and Ca 2+ with the seawater reservoir maintained a suf®cient Mg/Ca ratio for dolomite (rather than calcite) to form. Irregular crystal shapes resulted from dissolution, of both the dolomite and the enclosed ®ne calcitic shell debris, before ankerite precipitation during deep-burial diagenesis.

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Secondary Porosity Generation During Deep Burial Associated with Overpressure Leak-Off: Fulmar Formation, United Kingdom Central Graben

Cited by 12 publications

References 20 publications

Effect of Diagenesis on the Quality of Sandstone Reservoirs Exposed to High-Temperature, Overpressure, and CO2-Charging Conditions: A Case Study of Upper Miocene Huangliu Sandstones of Dongfang District, Yinggehai Basin, South China Sea

Effect of Diagenesis on the Quality of Sandstone Reservoirs Exposed to High-Temperature, Overpressure, and CO2-Charging Conditions: A Case Study of Upper Miocene Huangliu Sandstones of Dongfang District, Yinggehai Basin, South China Sea

Diagenetic Control of Reservoir Performance and Its Implications for Reservoir Prediction in Jinci Sandstone of Upper Carboniferous in the Middle East Ordos Basin

Disseminated ‘jigsaw piece’ dolomite in Upper Jurassic shelf sandstones, Central North Sea: an example of cement growth during bioturbation?

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