Current Abstract

May 10th, 2022 Meeting Abstract

Understanding hydrocarbon accumulation and production in Bio-Siliceous rock; a view from pore geometry



Over the years there has been substantial discussion about the many types of reservoirs found
in the Upper Monterey. A clear understanding however has been elusive. This presentation
will be an attempt to provide clarity or at least supply added information to further muddy the
water. Although the Lower Monterey is the primary source for California hydrocarbon
accumulations the Upper Monterey is not. It is often incorrectly considered as a primary source
or as a potential self-sourcing reservoir. All commercial Upper Monterey reservoirs have been
conventionally charged from Lower Monterey somewhere deeper in the basin. Regardless of
the silica phase present, there are only two types of reservoirs found; matrix supported and
intensely fractured (pseudo matrix).

Pore geometry controls reservoir performance. The diagenetic process is important, because it
controls pore geometry. Decades old assumptions about the diagenetic process do not fit the
hard data. Although temperature is generally thought to be the principal factor in silica phase
transformation it is not. A new phase diagram is proposed that better represents the hard data
across all the southern California basins. Pore geometry and capillary pressure as it relates to
hydrocarbon accumulation and production will be presented for all phases of bio-siliceous rock.
Understanding Pc and Pore geometry will lead to improved economics and lower risk in the
exploitation of these reservoirs.




Bryan Bell is the owner of Best Core Services. He has over 40 years of experience providing core
analysis expertise to the California petroleum industry. Bryan formerly owned and operated
Goode Core Analysis Service. He was also a regional manager for CoreLab before becoming a
petrophysical consultant for OXY and CRC. Best Core Services was opened October of 2016.