Role of Organic Species Dissolved in Formation Waters From Sedimentary Basins in Mineral Diagenesis

Kharaka, Yousif K.; Law, Leroy M.; Carothers, William W.; Goerlitz, Donald F.

doi:10.2110/pec.86.38.0111

Cited by 57 publications

(81 citation statements)

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“…The role of organic acids in the production of secondary porosity may be envisaged not only as a pH buffer (Kharaka et al, 1986), but also as a means by which the intrinsic rate of feldspar reaction may be increased. It is a combination of these effects which may serve to produce secondary porosity during burial diagenesis.…”

Section: Discussionmentioning

confidence: 99%

“…The rate and magnitude of feldspar removal is intimately linked with the ability to transport aluminium in solution. Aluminium is least soluble in the neutral pH 5-7 regime characteristic of most oilfield brines, due to its amphoteric chemical behaviour (Curtis, 1978;Kharaka et al, 1986). The problem of increasing feldspar dissolution then becomes one of enhancing A1 mobility within the fluid phase.…”

Section: Introductionmentioning

confidence: 99%

“…Oilfield brines are known to contain a range of organic acids of variable concentration (Carothers and Kharaka, 1978;Kharaka et al, 1986). The experiments of Surdam et al (1984) showed that organic acids such as acetic and oxalic are generated by compacting muds, particularly in the temperature range 70-100 ~ Acetic acid was found to enhance the solubility of aluminosilicates by one order of magnitude, and oxalic acid (difunctional and thus a better chelating agent) by up to three orders of magnitude.…”

Section: Introductionmentioning

confidence: 99%

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The effect of organic acids on the dissolution of K-feldspar under conditions relevant to burial diagenesis

Bevan

Savage

1989

Mineral. mag.

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The mechanism by which secondary porosity in sandstone reservoirs is produced is poorly understood. Previous hypotheses to account for the increased dissolution of framework silicates have invoked the introduction of acidic and/or organic-rich fluids capable of complexing metals. In order to evaluate the relative effects of these factors, the rates of K-feldspar dissolution have been measured at 70 ~ and 95 ~ at pH values of 1, 4, and 9, with and without oxalic acid, at a total pressure of 50 MPa, using direct sampling autoclaves. The presence of oxalic acid increased the dissolution rate of Kfeldspar at pH 4 and 9, but decreased the rate at pH 1 at both temperatures. The maximum increase in dissolution rate was observed at pH 4, 95 ~ by a factor -4. In oxalic-free experiments, the rate of dissolution increased an order of magnitude with each unit decrease in pH in the pH regime 1--4. In the presence of oxalic acid, this dependency of dissolution upon pH decreased to approximately an order of magnitude increase with each decrease in pH by 2pH units. The dissolution process was observed to be stoichiometric under all conditions, indicating that the mechanism by which rates are increased was not due to preferential complexation of aluminium, but rather by an increase in the overall solubility of feldspar in the neutral pH region. This regime of increased rate of reaction of feldspar coincides with that expected to be naturally buffered by the introduction of organic acids into a sandstone reservoir system.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of organic acids on the dissolution of K-feldspar under conditions relevant to burial diagenesis

Bevan

Savage

1989

Mineral. mag.

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“…It is also above the temperature window at which these acid anions are believed to break down. Decarboxylation of acetic acid, for example, is thought to begin at about 80-100ЊC (Drummond and Palmer 1986; Kharaka et al 1986;Lundegard and Kharaka 1994). On the basis of thermodynamic modeling of published formation-water chemistries, …”

Section: Organic-inorganic Interactionsmentioning

confidence: 99%

Ankerite Cementation in Deeply Buried Jurassic Sandstone Reservoirs of the Central North Sea

Hendry¹,

Wilkinson²,

Fallick³

et al. 2000

Journal of Sedimentary Research

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“…To understand the influence of the broad geological context of the formation water, the Carpenter and Miller, 1969Carpenter et al, 1974Carpenter, 1978Collins, 1969Collins, 1975Collins, 1987Conolly et al, 1990Crossey et al, 1986Edmunds et al, 1982Egeberg and Aargaard, 1989Ferguson et al, 1993Fisher and Boles, 1990Fisher and Kreitler, 1987Fontes and Matray, 1993h Hitchon et al, 1971Kharaka and Carothers, 1988Kharaka et al, 1986Kharaka et al, 1987Land and Macpherson, 1989Lundegard and Trevena, 1990Macpherson, 1992Merino, 1975Moldovanyi and Walter, 1992Morad et al, 1994Morton and Land, 1987Sanders, 1991Stueber and Walter, 1991Stueber et al, 1993Wilson and Long, 1993aWilson and Long, 1993b Klemme and Ulmishek (1991). The basin type and presence or absence of salt in the record have been taken from the publications or from regional geology publications.…”

Section: Introductionmentioning

confidence: 99%

Controls on halogen concentrations in sedimentary formation waters

Worden

1996

Mineral. mag.

108

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Chlorine is the most abundant halogen in sedimentary formation waters with concentrations from <100 to >250000 mg/1. Bromine is the second most abundant halogen at <1 mg/1 to >6000 rag/1 with iodine from <0.1 rag/1 to >100 mg/1 and fluorine from <0.1 rag/1 to 30 mg/L Chlorine and bromine show a strong systematic covariation suggesting that they are subject to the same controlling mechanisms. Fluorine only shows relatively high concentrations at elevated chlorine and bromine concentrations showing that fluorine, chlorine and bromine are possibly controlled by the same processes. Iodine does not correlate with any of the other halogens indicating that unique processes control iodine.Key geological parameters that influence chlorine and bromine (and possibly fluorine) concentrations are the presence of salt in a basin, the age of the reservoir unit and the kerogen-type within the main hydrocarbon source rock in a basin. The presence of salt in a basin shows that sea water was evaporated to halite saturation producing connate waters with high concentrations of chlorine and bromine. The presence of salt also leads to high salinity waters through water-salt interaction during burial and diagenesis. Tertiary reservoirs typically have much lower chlorine and bromine concentrations than Mesozoic or Palaeozoic reservoirs. The age of the reservoir unit may simply reflect the different amounts of time available for formation water to interact with salt. The dominance of type II marine kerogen in a basin leads to higher bromine concentrations. This may reflect the dominance of a marine influence in a basin which is more likely to lead to salt deposition than terrestrial depositional environments. Iodine concentrations are independent of all these parameters. Other geological parameters such as depth of burial, temperature, basin forming mechanism and reservoir lithology have no influence upon halogen concentrations.Key processes that affect halogen concentrations are sea water evaporation and dilution, water-salt interaction and input from organic sources. Chlorine and bromine data lie close to the experimentally-derived sea water evaporation trend showing that sea water evaporation may be an important general control on halogens. Sea water dilution is probably responsible for most low salinity formation water chlorine and bromine concentrations for the same reason. Sea water dilution can occur either by meteoric invasion during burial, or following uplift and erosion, or by diagenetic dehydration reactions. Water can interact with salt in a variety of ways: halite dissolution by congruent processes, halite recrystallization by incongruent processes, sylvite dissolution or recrystallization and halite fluid inclusion rupture. Halite dissolution will lead to high chlorine and relatively low bromine waters because halite contains little bromine. In contrast, halite recrystallization will lead to bromine-enhanced waters because NaBr dissolves preferentially to NaC1. The occurrence of dissolution or recrystallization wil...

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Role of Organic Species Dissolved in Formation Waters From Sedimentary Basins in Mineral Diagenesis

Cited by 57 publications

References 0 publications

The effect of organic acids on the dissolution of K-feldspar under conditions relevant to burial diagenesis

The effect of organic acids on the dissolution of K-feldspar under conditions relevant to burial diagenesis

Ankerite Cementation in Deeply Buried Jurassic Sandstone Reservoirs of the Central North Sea

Controls on halogen concentrations in sedimentary formation waters

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