A contract with a client includes the following information: area to be surveyed, expected starting and completion dates, number of samples, cost/sample and sample density. Petro-Find will obtain the required base maps from commercial sources.
Soil gas samples are usually taken on roughly a quarter-mile to one-mile spacing for reconnaissance surveys and as close as 200 meters for high-density surveys. Coordinates of each sampling point are established by GPS. A cordless rotary drill drives a special gas probe to a depth of 3-4 feet. The depth of sampling avoids contamination by any methane resulting from biological activity in surface soils. Soil gas is drawn by a syringe and injected into a pre-evacuated vial, which is shipped to our new lab at Innovation Place in Saskatoon for analysis by gas chromatograph.
Impediments to field operations are mainly wet soils, especially during spring breakup. No samples are taken for at least two days after a heavy rain because of the downward flushing of hydrocarbons in pore spaces. Operations can be conducted the year around.
The analysis, interpretation of data and final reports including contoured maps are currently done in Saskatoon. A fast turnaround time on analysis is achieved because the high-end gas chromatograph is equipped for back-flushing. The lab's location of less than one day's travel time from most major gas and oil districts in Saskatchewan and Alberta is also a major factor in the quick turnaround time after sampling. Also, the International Airport at Saskatoon allows samples to be flown in from remote locations and overseas projects.
The centralized lab facilities with fast turnaround time has the following major advantages:
A quick turnaround on sampling and analysis allows the follow-up of interesting trends before demobilization. Real-time decision-making thereby minimizes the number of mobilizations necessary to adequately explore an area.
Field efforts are optimized by providing intelligent location of infilling data points during a single survey day while minimizing the uncertainty from almost daily transient changes in soil gas concentration.
Cost savings for the client and Petro-Find. The accurate depiction of data at the time of the survey optimizes initial deployment of equipment thus avoiding the need to remobilize to the site for additional data.
It allows for the immediate checking of data that appears to be in error (i.e. too high or too low).
The planar coordinates (XY) of each sampling point are recorded by a GPS as well as in a field noteboook, downloaded to a computer at the end of each day's activities and plotted on a georeferenced base map to act as a guide for the next day's field work. The sample locations and associated concentrations for the analytes as well as ethane+ (total ethane, propane and butane concentrations) are plotted on clear overlay film and contoured using a traiangular, non-gridded computer program. For some reconnaissance surveys where the transects are very wide apart, bubble maps are produced instead. Petro-Find is self-sufficient in all aspects of map creation to guard against information leaks.
The major outputs include:
A written report of findings usually includes geomorphology, previous oil and gas activities, interpretation and recommendations. Any discovered anomalies are evaluated in terms of intensity of values, reasonable accessibility, coincidence with faulting and other structures, and seismic.
A base map showing sample locations, topography, culture, location of previous oil and gas drill holes, etc.
Overlay contour or bubble maps on clear showing methane, ethane, propane, butane and ethane plus (total C2,C3,C4) values.
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PETRO-FIND GEOCHEM LTD
INNOVATION PLACE
L004-410 Downey Road
Saskatoon, Saskatchewan, Canada S7N 4N1
Phone: (306)931-3156 Fax: (306)931-9773
E-Mail: plafleur@sasktel.net