Log Analysis of Shaly Sandstones
The presence of shale or clay in a sandstone reservoir has two effects on petrophysical logs: it lowers resistivity and it causes the porosity logs (sonic, neutron, and density) to generally record too high of a porosity. The lowering of formation resistivity results in the over estimation of the reservoir's water saturation so that a hydrocarbon zone appears water productive.
The course will review the types of clay minerals and how they affect both the resistivity and porosity logs. Next, the various methods for calculating volume of clay (Vcl) and the determination of effective porosity (PHIe) will be outlined. Before the total water saturation (Sw) is corrected to effective water saturation (Swe), a series of petrophysical cross-plots and calculations will be presented to determine if the reservoir is productive or not.
These cross-plots and calculations are very critical, because before geologists or engineers attempt to calculate Swe, they must first be sure the zone is productive. It must be remembered that shaly sand equations are designed to lower water saturation and the geologists or engineers need to be sure that they do not lower water saturation in a wet zone.
The class continues with a review and application of the various shaly sand equations. This review will include a discussion on when to apply the different equations based on logging suite and the type of clay distribution and concludes with a series of shaly sand case histories.
George Asquith, Ph.D.
Pevehouse Chair of Petroleum Geology. He is a Professor of Geosciences and co-director of the Center for Applied Petrophysical Studies at Texas Tech University. Twenty- five years of petroleum industry experience that included research geologist Atlantic-Richfield Co., staff geologist ALPAR Resources, chief geologist Search Drilling Co., district geologist Pioneer Production Corp., and project leader Mesa Limited Partnerships. He has published one hundred and twenty publications, including 5 books in the fields of petrophysics, carbonate and clastic sedimentation/petrology, and computer geology.
Dr. Asquith received the Distinguished Service Award from the WTGS 1999, and the Distinguished Lecturer for the Society of Professional Well Log Analysts (1991-1992 and 1994-1995). He was a lecturer for the AAPG Subsurface Carbonate Depositional Modeling School (1980-1986) and received the Monroe Cheney Science Award from the Southwest AAPG 2001.
|G031132Q||Dec 9||8:00 am - 5:00 pm|
|Midland College PPDC|
|Registered: 8||8.0 Hours|