SPE Journal
Volume 14,
Number 3,
September 2009,
pp. 524-531
Summary
Pore geometrical parameters for the M_1 petrophysical rock type of the Arab
D limestone in Ghawar field have been related to static and dynamic reservoir
properties and geological facies (Clerke et al. 2008). The M_1 bimodal pore
system is the most common and important member of a new set of ultimate
recovery petrophysical rock types (URPRT), which uses a new pore system
classification for the Arab D limestone. The dynamic reservoir property results
for the bimodal M_1 are reviewed here. The roles played by the pore system
parameters describing the macropores (M) and micropores (Type 1) within the M_1
in permeability, imbibition oil relative permeability, and microscopic
displacement efficiency are examined in detail. All pore systems are analyzed
by the Thomeer method using an extensive mercury injection capillary pressure
(MICP) data set in conjunction with dynamic experiments performed on samples
prepared using the same wettability restoration. Effects commonly ascribed to
wettability changes are observed by changes in the distribution of porosity
between the M and Type 1 subsystems.
An extensive study of the pore systems of the Ghawar Arab D limestone
gathered a large and comprehensive MICP data set (484 samples) (Clerke et al.
2008; Cantrell and Hagerty 1999, 2003; Clerke 2003, 2004; Ahr et al. 2005). All
MICP data were type-curve matched by Thomeer functions (Clerke et al. 2008;
Thomeer 1960). The study of this carefully prepared MICP data is the foundation
for a new pore system classification. The new classification is built upon
intrinsic, fundamental, and separate maximum pore-throat diameter modal
elements named "porositons" (Clerke 2008; Ahr et al. 2005). Porositons
are stable and recurring modes in the statistics of the Thomeer maximum
pore-throat diameter of these carbonate pore systems. Porositon combinations
are used to construct meaningful petrophysical rock types. Petrophysical rock
types (PRTs) are defined by Clerke et al. (2008) as objects or combinations of
objects that are present in the 3D space of the Thomeer pore-system parameters.
Porositons are a new PRT object type; other PRT objects are clusters, trends,
and surfaces. By constructing PRTs from porositons, strong relationships are
found connecting the geological facies, PRTs, and reservoir-flow properties of
these complex multimodal carbonate rocks (Clerke et al. 2008). These
relationships demonstrate that these PRTs are important for defining ultimate
recovery.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
18 November 2006
- Meeting paper published:
11 March 2007
- Revised manuscript received:
24 March 2009
- Manuscript approved:
26 March 2009
- Published online:
16 July 2009
- Version of record:
28 September 2009