Consulting within Canada and internationally, we have a proven track record of tackling difficult evaluations.
Click on the case studies below to see how our wealth of experience in the field of petrophysics can assist your needs, and help you increase your production output.
Oil Shale Evaluation
Oil shale in Canada is relatively new within the last few years, and most operators are still in the investigative stages evaluating zones of interest that contain total organic carbon (TOC) values of a certain minimum.
Our last oil shale work was investigating oil shale potential within a Cretaceous section of the Western Canadian Sedimentary Basin (WCSB).
Several vertical wells were drilled along a very long trend, and full diameter core along with rotary cores were taken.
Wire-line logging was very extensive, and included Nuclear Magnetic Resonance (NMR), using a variety T2 cut-offs to best determine effective porosity, lithology density scanner technology to assist in determining the rock components, and di-pole sonic wire-line logging. Resistivity logging was of the array induction type, due to the oil based mud used within the drilling process.
Tight rock analysis (TRA) on both the full diameter and rotary core plugs were done, both for total and effective porosity measurements, which included permeability (K), density, and water saturation.
Various other core studies list below was also performed.
- Image analysis
- Rock composition
- X-Ray diffraction (XRD)
- Scratch test
- Mercury injection capillary pressure (MICP)
- Rock eval, geochemistry
- Total organic content (TOC)
All of the above services were integrated with the wire line logs, to attempt to verify effective shale rock porosity, bound and free fluid index to determine water saturations, and grain density matrix.
A brittleness index, kerogen type, Young's modulus, delta log R, K, and volume of kerogen was calculated using a petrophysical software written for shale oil evaluation.
Petrophysical evaluations were done on the current wells drilled, using the learning's of the measured information mentioned above, like effective porosity, permeability, grain density matrix, and water saturations.
Appropriate NMR T2 cut-offs were determined from core analysis, and used to calibrate the NMR for effective porosity and NMR water saturations, bound and free.
Once we were satisfied with all the variables to use, a regional study of 100's of wells was done, and many map able parameters produced, like cleaner rock from the shale rock of which was called a net pay potential, along with using a minimum closure stress cut-off, gross potential was dependent on the volume of shale (VSH) being opened up to include more meters of rock, along with using a minimum closure stress pressure. Effective porosity, average permeability (K) effective water saturation (SW), and total organic carbon (TOC) along with a brittleness index were collected for mapping. The VSH method used was not the gamma ray but the neutron porosity curve, and the inputs were the lowest neutron porosity was the cleanest, while the highest neutron porosity was the most shale. A linear approach to calculate the VSH was used.
This study was very intricate and detailed, and lead to a qualified approach that can be used for future shale oil study areas.
Gas Shale Evaluation
Shale gas petrophysical studies have been done in north-east British Columbia to determine hydrocarbon areas that would be most beneficial to economic recoveries. One of the geologic sections of interest is the Montney shale, however the Montney is not really a shale as first thought, and is now described as a quartz rich carbonate geologic zone of interest with clay particles, and radioactive components, as described in well site geologic samples.
The Montney has been divided up into several smaller sections of interest, and over a very large regional area a petrophysical study was completed to determine the areas that were better from each other. The technology used to determine the sweet spots was the Di-Pole Sonic logging technology, using both the compressional and shear data. There were about 40 wells with Di-Pole technology varying in vintages, and the older logs needed to be standardized to the newer Di-Pole logging services.
Modeling within each of these wells was done, in order to back predict the shear data with itself in order to see how well the predicated function worked.
A brittleness index function was developed to determine where subtle coarser quartz accumulations could be contained. This index was compared to the volume of shale (VSH) calculations using the neutron porosity curve as the end points for the cleanest and most shaley lines using a linear equation.
The brittleness index was mapped as a thickness over each section of the Montney using certain average cutoffs, and then compared to geophysical work. The bright trends identified by petrophysics agreed quite well with the bright trends identified by the geophysical work.
This study solidified that the two sciences are very closely linked, and can be used as a team approach to identify areas of regional interest, to drill the directional or horizontal wells, to get the hydrocarbon economics to a successful rate of return.
Tight Rock Oil Petrophysics
Regional studies over hundreds of wells have been done to map average porosity, water saturation and permeability for example over the basal Cretaceous section in the vertical wells within an area. This deterministic approach identified the areas with the best porosity, and a probabilistic approach was used to determine whether the areas of higher water saturation were actually water bearing, or due to mineralogy like contained massive chert, which trends to capture water, and is immovable water, and therefore will not flow water.
The probabilistic approach which was modeled to core descriptions along with well-site geologic description's, identified larger areas that were tested, and produced oil with no water.
Many horizontal wells are being drilled in mature areas which has infrastructure, and they produce hundreds of barrels of clean oil with no water, and are highly profitable using the multi-stage completion and fracking, to improve the oil drainage.