KarstBase a bibliography database in karst and cave science.
Featured articles from Cave & Karst Science Journals
Characterization of minothems at Libiola (NW Italy): morphological, mineralogical, and geochemical study, Carbone Cristina; Dinelli Enrico; De Waele Jo
Chemistry and Karst, White, William B.
The karst paradigm: changes, trends and perspectives, Klimchouk, Alexander
Long-term erosion rate measurements in gypsum caves of Sorbas (SE Spain) by the Micro-Erosion Meter method, Sanna, Laura; De Waele, Jo; Calaforra, José Maria; Forti, Paolo
The use of damaged speleothems and in situ fault displacement monitoring to characterise active tectonic structures: an example from Zapadni Cave, Czech Republic , Briestensky, Milos; Stemberk, Josef; Rowberry, Matt D.;
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Calculating flux to predict future cave radon concentrations, Rowberry, Matt; Marti, Xavi; Frontera, Carlos; Van De Wiel, Marco; Briestensky, Milos
Microbial mediation of complex subterranean mineral structures, Tirato, Nicola; Torriano, Stefano F.F;, Monteux, Sylvain; Sauro, Francesco; De Waele, Jo; Lavagna, Maria Luisa; D’Angeli, Ilenia Maria; Chailloux, Daniel; Renda, Michel; Eglinton, Timothy I.; Bontognali, Tomaso Renzo Rezio
Evidence of a plate-wide tectonic pressure pulse provided by extensometric monitoring in the Balkan Mountains (Bulgaria), Briestensky, Milos; Rowberry, Matt; Stemberk, Josef; Stefanov, Petar; Vozar, Jozef; Sebela, Stanka; Petro, Lubomir; Bella, Pavel; Gaal, Ludovit; Ormukov, Cholponbek;
Aapg Bulletin/AAPG Bulletin, 2003, Vol 87, Issue 8, p. 1509-1529
Discrimination of effective from ineffective porosity in heterogeneous Cretaceous carbonates, Al Ghubar field, Oman
Smith L. B. , Eberli G. P. , Masaferro J. L. , Aldhahab S.
Abstract:
The Natih E heavy-oil reservoir (21j API) atAl Ghubar field, Oman has produced less than 5% of the calculated oil in place. Porosity logs used to calculate reserves show high porosity throughout the reservoir, but further analysis of the only continuous core taken from the field indicates that much of the porosity is ineffective. There are four heavily oil-stained, high-permeability skeletalpelletal grainstone units with interparticle porosity in the core that probably contributed most of the production. The four permeable grainstone units occur at the top of small-scale accommodation cycles that have wackestone and packstone bases. These grainstones make up about 20% of the total thickness of the porous Natih E reservoir. The other 80% is composed of packstone and wackestone with ineffective microporosity, interparticle porosity in burrows, and isolated moldic and intraskeletal porosity. The small-scale reservoirbearing cycles can be correlated across the field using the separation between the medium and deep induction curves as a guide. Resistivity logs are the most reliable tool to distinguish effective from ineffective porosity. Most high-permeability grainstone units have deep induction values more than 100 ohmmand separation of more than 10 ohm m between the medium and deep induction curves. The ineffective intervals with microporosity, burrow porosity, and moldic porosity have lower resistivity and little separation between the medium and deep induction curves
The Natih E heavy-oil reservoir (21j API) atAl Ghubar field, Oman has produced less than 5% of the calculated oil in place. Porosity logs used to calculate reserves show high porosity throughout the reservoir, but further analysis of the only continuous core taken from the field indicates that much of the porosity is ineffective. There are four heavily oil-stained, high-permeability skeletalpelletal grainstone units with interparticle porosity in the core that probably contributed most of the production. The four permeable grainstone units occur at the top of small-scale accommodation cycles that have wackestone and packstone bases. These grainstones make up about 20% of the total thickness of the porous Natih E reservoir. The other 80% is composed of packstone and wackestone with ineffective microporosity, interparticle porosity in burrows, and isolated moldic and intraskeletal porosity. The small-scale reservoirbearing cycles can be correlated across the field using the separation between the medium and deep induction curves as a guide. Resistivity logs are the most reliable tool to distinguish effective from ineffective porosity. Most high-permeability grainstone units have deep induction values more than 100 ohmmand separation of more than 10 ohm m between the medium and deep induction curves. The ineffective intervals with microporosity, burrow porosity, and moldic porosity have lower resistivity and little separation between the medium and deep induction curves
Keywords: carbonate reservoirs, hypogene karst