geochemistry

Our partner's geochemical workhorse is its X-Ray Fluorescence (XRF) capabilities, providing rapid quantitative elemental analysis of well cuttings.   From the fundamental elemental data, mineralogical and lithological modelling can be achieved along with determination of various geomechanical properties.  Our XRF service is available both at the rig site and in near-field laboratories.  Field-based XRF brings new attention to areas of the formation that are visually homogenous and has allowed DWL to launch it's Hybrid Mud Logging service.

No longer do you need to wait months for testing results; data is produced and delivered in as near as real-time as the sample can be processed. This information is customized for finding the sweet spots, making more precise geosteering decisions - Chemosteering - and fingerprinting the well through chemostratigraphic evaluation.

While unconventional resource plays present a unique set of challenges to operators, and despite advances in horizontal drilling and hydraulic fracturing technology that have made production from these resources commercially viable, there remain economic issues.  One is the cost constraint on obtaining the very best geological knowledge to develop a field to its maximum potential.

XRF elemental analysis is a powerful, cost-effective method for exploiting the rich data available from well cuttings.  XRF provides a deeper look at rock samples with more precision than traditional microscopic examination. These tools complement the mud-logger’s expertise in evaluating and analyzing well cuttings by offering a precise quantification of the minerals and elements.  This data is logged for analysis alongside visual descriptions and formation gas data, and can help provide indicators of geological history, basin maturity, low-grade metamorphism, and a characterization of lithologies.

Also, consider that the typical North American well has approximately 25 to 50 fracture stages, and, as lateral wells become longer, sometimes more.  Operators report that they still suffer very low production rates; low production rates caused largely by the root-cause of insufficient sub-surface geological knowledge. XRF technology can increase geological certainty and lead operators to better place fracturing stages or even reduce the number of them. Similarly, with better geological information, wells can be better placed throughout a field, reducing 'parent-child' production problems.  XRF analysis from Diversified leads to value that far outweighs the cost. 

The following lists some of the applications XRF analysis can be used for:

• Chemostratigraphy – precise elemental correlation within a formation for picking casing points, coring points, well TD, geosteering and geostopping
• To determine organic content – paleoredox modelling of certain key elements
• Chemical gamma ray – sample correlation to LWD-GR with radioactive elements
• Mineral modelling – determine bulk mineralogy with elemental composition
• Lithological modelling – determine or confirm lithology via elements and mineralogy
• Aid determination of fracability – brittleness calculations, biogenic vs. detrital silica
• Aid determination of reservoir quality – TOC proxies, mineralogy
• Depositional environment and provenance
• And more …

 XRF technology is successful in the most difficult of drilling situations, including high pressure/high temperature wells where downhole tool failure is common and expensive.  When gamma becomes insignificant or other tools fail, the mineralogical data from XRF can assist in calling tops, recognizing the formations, and staying in the pay zone.  Having the comprehensive understanding of rock properties that XRD and XRF provide is often required to steer these horizontal wells within a narrow pay zone while avoiding geo-hazards. XRD and XRF data also help operators design successful fracture jobs to stimulate the greatest recoverable reserves. 

 In brief, the XRF technique determines the elemental composition of a sample by measuring characteristic element-specific "secondary" or fluorescent X-rays coming from a sample that has been excited by being bombarded with high-energy X-rays or gamma rays from the XRF instrument.

Diversified Well Logging uses an energy dispersive spectrometer (ED-XRF) with rhodium X-ray tubes for excitation to perform its analyses. These instruments are very effective for high-speed, multi-element analysis, whether in the laboratory or in the field.

 Chemosteering - real-time evaluation of elemental data to determine chemostratigraphic packages and units for steering.  Deliverables include measured depths of packages and units, cross-plots of relevant elements, descriptions of defining characteristics, and elemental gamma ray curve.

Mineralogy & Rock Mechanics - includes correlation of client's elemental and XRD data to build a multi-mineral model from elemental data and determination of elemental-derived rock mechanics using published values of Poisson's Ratio and Young's Modulus.

Sedimentology & Depositional Environment - evaluation of major elements relating to sediment flux to the basin, which includes proxies for carbonate type and abundance, clastics grain size, and detrital and biogenic silica.  Evaluation of redox sensitive trace elements and sulfur are used to determine redox conditions at the time of deposition correlations to TOC, and insights into TOC preservation and distribution