Research projects

 
Fundamental processes at the interface between dissimiliar mineral surfaces in fluids - applications to quartz-clay interaction (pressure solution) and precipitation of carbonates on mica: with Prof Jaccob Israelachvili, UCSB Engineering, post -doc Norma Alcantar, UCSB Engineering and Dr. Patty McGuiggan, National Institute Science and Technology. Project Summary:: Clay minerals have been shown to enhance pressure solution of quartz and carbonates. Carbonate minerals and other phases have also been shown to grow selectively within biotite cleavages but not in muscovite. We are using geologic observation to constrain a series of Surface Force Apparatus and AFM laboratory experiments. These results will allow us to understand the cause of enhanced pressure solution at clay-quartz interfaces as well as other effects at clay -fluid interfaces.

Cementation related to fluid flow in faults and fractures, Southern California: constraining the timing, duration, magnitude, and origin: with Peter Eichhubl (Monterey Bay Marine Lab), Mark Grivetti, Dames and Moore, graduate student Renee Perez Project Summary:: Fluid flow in fracure/faults has been postulated as important mechanism for basin scale mass transfer and cementation. Peter Eichhubl has recently completed a field and geochemical study of carbonate vein-filling in the Monterey Formation. His work shows that vein-fill components, based on Sr isotopic studies have only, have only been moved on a vertical scale of a few hundred meters. Lateral flow into the fault zones is believed to be important in order to account for the volume of fluid required.

In a new study along the Refugio Fault in the Santa Barbara area (with M. Grivetti) we have found clear evidence of meteroic circulation of fluids to a depth sufficient to heat the water to about 80C, extremely light carbon isotopic signatures indicating oxidation of methane, and outstanding petrographic evidence for episodic pulses of fluid in the form of laminations of detrial siliciclastic sand grains at the start of each fluid pulse. Massive calcite cementation occurs at each end of the 24 km long fault zone. U series datres have been obtained from the calcites by Dr. Jim Chen, Cal Tech. Hydrocarbons and hot fluids were leaking up faults along the basin margin as recently as a few hundred thousand years ago.

Fluid/rock interaction in the Mission and Tecolote Tunnels: a 40 to 80 year record of carbonate cementation: with Prof Jordan Clark and grad student Laura Rademacher (UCSB Geology). Project Summary:: Tunnels drilled through the Santa Ynez Mountains in the early 1900's (Mission Tunnel) and the 1960's (Tecolote Tunnel) provide a natural laboratory in which to study water-rock interaction in which the flow path, flow time, and imput (meteoric) and output (seeps into the tunnels) fluid compositions can be well constrained. The influence of rock type can also be assessed as the formation are subvertical and the flow paths are roughly parallel to bedding. Inaddition to water rock/interaction studies, we are measuring carbon -oxygen isotopes of some remarkable meter scale stalactites, which have precipitated in the Mission Tunnel. These stalactites are being studied for their value as a possible hundred year climate record. The stalactites show covariation of carbon and oxygen by at least one per mil although tempereature of crystallization over the past 90 years has been relatively constant.  

Effect of hydrocarbon gas and oil emplacement on sandstone diagenesis. Project Summary:: This is an on going project to look at possible influence of the presence of hydrocarbons on diagenesis. Hydrocarbon emplacement is believed by many to shut down diagnetic processes due to the exclusion of water from the pore spaces and to the reduced permeability of water in the system. My studies in Tertiary clastic reservoirs of the San Joaqun basin has shown that plagioclase porosity is enhanced in the hydrocarbon enriched zone but not in the gas zone--even though both zones presently contain equal water saturation. I'm currently looking at the Elk Hills reservoir where permeability-porosity differences are reported between the hydrocarbon and non-hydrocarbon parts of the reservoir. The effect of hydrocarbons may be their ability to influence pore water composition (e.g providing organic acids).

Evidence for bacterial mediated processes in hydrocarbon reservoirs: with Vicki Orphan, (Monterey Bay Marine Lab). Project Summary:: We are presently sampling hydrocarbon reservoirs within the San Joaquin basin to look for the presence and distribution of thermophilic bacteria and bacterial-induced processes in hydrocarbon reservoirs. We currently have sampled reservoirs from 60 to about 125C and find thermophillic bacteria to be widespread. Vicki Orphan is identifying the bacteria from cultures.

Temporal variation in natural methane seep rate due to tides and other factors, Coal Oil Point area, California. A joint project with Jordan Clark, Libe Washburn, and Ira Leifer. Project Summary. A large natural methane seep, occurring a kilometer offshore in 64m of water, has been monitored on an hourly basis for 10 months. About 16.4 cubic meters (580 MCF) of methane/day is captured from the seep by two large steel tents (each 30m by 30m) open at the bottom to the ocean. The gas is piped to shore where it is metered and processed. We are analysing the variation in seep rate and composition as a function of anthropogenic and natural factors. The affect of hydrocarbon production from the nearby South Ellwood oil field on this seep is not clear. There is no clear relation between seep rate and change in formation pressure in key wells close to feeder faults over a 10 year period, and from a month long platform shutdown. Results, however, show a clear tidal influence on the gas flow rate. These results are the first documentation of the effect of tides on natural gas seeps.