The course is designed to be of benefit to geologists, engineers and technical support people who are involved in oil and gas exploration and production working in areas with a large number of “Old” well logs. As the title states, this is a quick review of the unique methods used in the analysis of older well logs. The course will be a useful to new personnel in the oil and gas industry as well as more experienced professionals who need a review.
At the conclusion of the one day course, participants should be able to do the following: Scan a well log to determine zones that potentially could be hydrocarbon productive.
Determine formation temperature and correct both drilling fluids and formation water resistivities to formation temperature. Also be able to make basic bore hole and thin bed corrections to the resistivity logs.
Determine formation water resistivity using well logging methods.
Determine porosity from resistivity logs using numerous well logs and methods.
Normalize old gamma ray log to API units and normalize old neutron logs to determine porosity.
Make invasion corrections of resistivity logs to true formation resistivity.
Understand how the Archie parameters are obtained, so that together with log data, water saturation and hydrocarbon saturation can be derived.
The participants will also be exposed to additional methods including cross plots to help in the determination of the productive potential of the zone being analyzed.
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By the end of the course participants should be able to accomplish the following:
- Understand DST pressure charts to identify obvious formation damage & depletion (small & reservoir) and mechanical problems (eg. tool plugging).
- Recognize high vs. low permeability tests.
- Understand why data from cores and logs often conflict with DST data.
- “Make more sense” of DST results printed in IHS well cards and field reports where no chart is available and even estimate approximate permeability & damage in some cases.
- Identify presence of poorly connected natural fractures, which can be accessed with horizontal wells.
- Appreciate where recoveries of “oil cut mud” and “gas cut mud” may be significant from an exploration standpoint for horizontal wells and multi-stage fracs.
- Determine when a gas test is co-producing water.
- Identify gas presence even where no gas was reported in certain tests.
- Identify potential oil zones from DSTs which recovered no oil (from the chart shape and air blow description).
- Estimate the approximate gas rate in DSTs of “GTS TSTM” by knowing the time gas took to reach the surface and the air volume of the test string.
- Make a decision as to whether old DSTs can be recompleted as commercial wells today from limited information.
- Assess DSTs of water zones for potential water disposal wells or source of water for frac’s.