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Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea

Authors
Publisher
Geological Society Publishing House
Publication Date
Keywords
  • The Permeability And Capillary Entry Pressure Of Chalk Reservoirs Are Controlled By Their Porosity A
  • Measured Permeabilities Are In The Range 0
  • 025-5
  • 3 Md And Are Successfully Predicted By Use Of The Kozeny Equation
  • In This Paper We Focus On The Factors That Control Specific Surface Area
  • Fifty-Nine Tor And Ekofisk Formation Chalk Samples From Five North Sea Chalk Reservoirs Were Investi
  • All Contain Quartz And Clay Minerals
  • Most Commonly Kaolinite And Smectite
  • With Trace Amounts Of Illite
  • The Contents Of Calcite And Quartz Are Inversely Correlated And Both Are Independent Of The Content
  • We Thus Infer That The Main Part Of The Silica Is Of Biogenic Origin
  • The Specific Surface Area Of The Chalk Is Mainly Controlled By Clay Content
  • The Specific Surface Area Of Calcite Is Determined By The Individual Calcite Crystal Size And Is Not
  • The Specific Surface Area Of Calcite Increases With Increasing Content Of Quartz And Clays
  • These Constituents May Inhibit Recrystallization Of Calcite And Thus Preserve High 2 Specific Surfac
  • Our Data Accord With The Following Specific Surface Areas (M(2) G(-1)): Calcite Between 0
  • 5 And 3
  • 5
  • Quartz About 5
  • Kaolinite About 15
  • And Smectite About 60
Disciplines
  • Earth Science

Abstract

Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea - DTU Orbit (18/04/14) Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea - DTU Orbit (18/04/14) Influence of clay and silica on permeability and capillary entry pressure of chalk reservoirs in the North Sea The permeability and capillary entry pressure of chalk reservoirs are controlled by their porosity and specific surface area. Measured permeabilities are in the range 0.025-5.3 mD and are successfully predicted by use of the Kozeny equation. In this paper we focus on the factors that control specific surface area. Fifty-nine Tor and Ekofisk Formation chalk samples from five North Sea chalk reservoirs were investigated. All contain quartz and clay minerals, most commonly kaolinite and smectite, with trace amounts of illite. The contents of calcite and quartz are inversely correlated and both are independent of the content of clays. We thus infer that the main part of the silica is of biogenic origin. The specific surface area of the chalk is mainly controlled by clay content. The specific surface area of calcite is determined by the individual calcite crystal size and is not dependent on stratigraphic variations in fossil size. The specific surface area of calcite increases with increasing content of quartz and clays. These constituents may inhibit recrystallization of calcite and thus preserve high 2 specific surface area. Our data accord with the following specific surface areas (m(2) g(-1)): calcite between 0.5 and 3.5, quartz about 5, kaolinite about 15, and smectite about 60. General information State: Published Organisations: Department of Environmental Engineering Authors: Røgen, B. (Intern), Fabricius, I. L. (Intern) Keywords: (porosity (rock), specific surface area, insoluble residue, petrophysical properties, North Sea) Pages: 287-293 Publication date: 2002 Main Research Area: Technical/natural sciences

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