Abstract

Unconventional reservoir development plans often make use of multiple horizontal wells drilled off pads. Logging or coring data is seldom acquired in these horizontal wells although petrophysical and geomechanical properties can vary significantly over relatively short distances impacting the performance of the wells.

A program has been adopted to collect and analyze, via X-Ray Fluorescence (XRF), drill cuttings from pad Hz wells to provide an accurate evaluation of mineralogical, petrophysical and geomechanical properties in order to optimize the completion and hydraulic fracturing programs. Multiple XRF machines have been purchased, a core and cuttings lab constructed in our head office and a team trained to carry out the work. To date, over 10000 samples from more than 70 wells have been examined.

XRF spectrometer is an x-ray instrument used for routine, non-destructive chemical analyses of rocks, minerals, sediments and fluids. It is one of the simplest, accurate and most economic analytical methods for the determination of the chemical composition of many types of materials. Currently available in hand-held, portable and lab benchtop models, XRF spectrometers have proved their use in the lab and the field.

This presentation will show methodologies and results of this work using examples from a Horn River Shale gas development project and a Colombia unconventional exploration program. The analysis of drill cuttings are used to model total organic carbon (TOC), geomechanical properties, mineralogy, grain densities, a GR log and even porosity. Well correlations are much more robust than the one which could be made by simple cuttings descriptions and drilling data alone.

These measurements would be very costly to acquire in horizontal wells via conventional logs and cores, however with XRF the data is available at low cost and high reliability. In the exploration programs, drilling progress is monitored for identifing formation tops and select casing, coring and TD points with high confidence by bringing XRF to the wellsite. This not only provides near real time logging, it also engages the wellsite geologist at a much higher level.

This tool and in-house facility has allowed for logging many more wellbores and with more data than would be available via logs and cores alone. It has saved significant costs and has been a success story in our company.

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