Geology Reference
In-Depth Information
dolomites depend on the location within the dolomitiz-
ing system (Saller and Henderson 1998). Porosity and
permeability are low in platform interior, and higher
near platform margin settings.
Sun (1995), summarizing the published records of
hydrocarbon-producing dolomite reservoirs, distin-
guished four basic types:
(1)
Peritidal-dominated carbonates
, characterized
by low matrix porosity and permeability and strong do-
lomitization. Economic reservoirs are possible if the
rocks are karstified and fractured.
(2)
Subtidal dolomite associated with evaporitic
tidal flat/lagoons
, typically formed in shallowing-up-
ward cycles. The best reservoirs occur in high-energy,
grain-dominated subtidal carbonates forming the lower
parts of the cycles, or in low-energy mudstone/wacke-
stone with a coarse crystalline fabric. Primary inter-
granular porosity is preserved due to the relatively arid
climate and because impermeable tidal-flat dolomite
and anhydrite, forming the caps of the upward-shoal-
ing cycles seal off the subtidal carbonates.
(3)
Subtidal dolomite associated with basinal
evaporite
commonly bears no direct relationship to
depositional trends due to the strong overprint of pri-
Fig. 17.4.
Fractures and microcracks
can create permeabil-
ity and porosity in low-porosity limestones. The SEM pho-
tograph shows a submicroscopic microcrack partly filled with
heavy oil, being a part of a network of small fractures within
bioclastic wackestones. Identifying cracks is a key point for
the characterization of fracture reservoirs. Late Cretaceous
(Mishrif Formation): Subsurface, Middle East.
Box 17.1.
Selected carbonate reservoir studies. A list of studies made in the 1950s to1970s can be found in Mazzullo
(1980).
Lacustrine carbonates:
Katz 1990; Lomando et al. 1994
Shelf carbonates:
Burchette and Britton 1985; Chidsey
et al. 1996; Croft et al. 1980; Grötsch et al. 1999, 2003;
Jordan et al. 1985; Kopaska-Merkel 1994; Kopaska-
Merkel et al. 1994; Lindsay and Kendall 1985; Lomando
et al. 1985; Loucks and Anderson 1985; Madi et al.
2000; Miller 1985; Noack and Schroeder 2003; Vahren-
kamp and Grötsch 1994
Shoals:
Ahr and Walters 1985; Asquith 1986; Budd 2002;
Burchette et al. 1990; Carozzi and Reichelderfer 1987;
Choquette and Steinen 1985; Handford 1988; Hovorka
et al. 1993; Keith and Zuppann 1993; Kelleher and
Smosna 1993; Longacre and Ginger 1988; Moore et al.
1986; Parham and Sutterlin 1993; Sellwood and Beckett
1991; Sellwood et al. 1989
Subunconformity reservoirs:
Budd et al.1995; Hopkins
1999; Montgomery et al. 2000
Subaerially exposed carbonates:
Budd et al. 1995;
Dickson and Saller 1995; Esteban and Klappa 1983,
1993; Friedman 1980; Hopkins 1999; Kerans 1997;
Longman 1981; Read and Horbury 1993; Saller et al.
1994, 1999; Wagner et al. 1995
Paleokarst and paleocaves:
Cater and Gillcrist 1994;
Fritz et al. 1993; Hopkins 1999; Hurley et al. 1994;
Johnson 1994; Loucks 1999 (contains a list of 35 case
studies ranging from the Ordovician to Early Creta-
ceous!); Loucks and Anderson 1985; Purdy and
Waltham 1999; Saller et al. 1994; Tinker and Mruk
1995; Wang and Al-Aasm 2002
Reef reservoirs:
Ahr and Ross 1982;
Alam et al. 1999;
Alsharhan 1995; Amthor et al. 1994; Armstrong et al.
1980; Baria et al. 1982; Crevello et al. 1985; Cys and
Mazzullo 1985; Gill 1985; Grötsch and Mercadier 1999;
Herrod et al. 1985; Jardine and Wilshart 1987; Jordan
and Abdullah 1988; Klovan 1964;
Kuznetsov 1997;
Lasemi et al. 1994; Longman 1985; Malek-Aslani 1985;
Nayoan et al. 1981; Pomar and Ward 1999; Precht 1986;
Roylance 1990; Schmidt et al. 1985; Stemmerik and
Larsen 1993; Sun and Wright 1998; Weidlich 2002; Wil-
son et al. 1997. For further references compare also Box
7.7!
Turbidites:
Duvernory and Reulet 1977; Cazzola and
Soudt 1993; Enos 1985, 1988; Hertig et al. 1994
Chalks:
D'Heur 1984; Feazel et al. 1985, 1988; Hardman
1982; Maliva and Dickson 1992; Scholle 1977; Van den
Bark and Thomas 1980
Fracture reservoirs:
Aguillra 1995; Barchi et al. 1993;
Irish and Kempthorne 1987; Kulander et al. 1990;
Longman 1985; McQuillan 1985; Narr and Curie 1984;
Nelson 1985; Nelson et al. 2000; Reijers and Bartok
1985; Renner 1988; Roehl and Weinbrandt 1985; Van
Golf-Racht 1996
Dolomite reservoirs:
Allan and Wiggins 1993; Davies
1979; Gosh et al. 1989; Loucks and Anderson 1985;
Luo and Machel 1995; Purser 1985; Ruzyla and Fried-
man 1985; Saller and Henderson 1998; Schauer and
Aigner 1997; Schmoker et al. 1985; Sun 1995; Weyl
1960; Zeidan 1994
