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Aubrey Whymark BSc MSc FGS
Wellsite Geologist, Geosteerer & Biosteerer
A wellsite geologist acts as the interface between the geological and drilling operations on the rig. The wellsite geologist reports to the operations geologist. They are involved in all geological related issues on the rig; ensuring the smooth running of operations; ensuring all issues are communicated; producing daily reports as and when required, identifying and troubleshooting problems; quality controlling; supervising mudloggers, LWD and DD operations; overseeing all drilling and wireline operations and having significant input into safety. Furthermore, they can be involved in planning and pre-drilling stages and in post-drilling appraisals and evaluations. 

​The precise role will depend on the well being drilled: vertical, deviated or horizontal; production or exploration, high temperature / high pressure, whether geosteering is required, etc. Wellsite geologists will have their specialisations but will also be highly adaptable and have a good working knowledge of both geology and engineering aspects.

Looking at the rock is an important aspect of the wellsite geological role​, but the job encompasses far more. The wellsite geologist sifts through a large quantity of complex data from multiple sources that must be processed, understood, evaluated, communicated and reacted upon if required. The wellsite geologist is the go-between in geological and engineering / drilling issues. The wellsite geologist works in a team to ensure the job objectives are achieved in a safe and timely manner.
Planning and Researching
  • Well planning: Comparing offset well data, predicting landing points and bedding inclination, standardising log picks and making correlations, identifying potential structural problems, drawing attention to potential collision or interference problems, identifying porosity trends / shifts, identifying potential mud loss zones, checking that the correct LWD and Motor / RSS are being run to achieve objectives, checking the well plan, identifying any issues prior to drilling.
  • Carrying out pilot studies to assess the viability of carbonate biosteering and geosteering. This includes construction of zonation schemes utilising microfacies, microfossils and log data, assessment of lateral variability and porosity migration, standardisation of field data and re-evaluation of the structural model.

  • Reviewing data for post-drilling appraisals to re-evaluate the field structure and the success of laterals in terms of target and fracture penetration. Identification of potential horizons / areas for future drilling.
Real-Time Drilling
  • ​​​Supervising mudlogging, LWD and DD operations.

  • Troubleshooting and communicating issues where necessary.

  • Real-time analysis and description of cuttings samples. This can include, if desired, microfossils and microfacies / lithology in thin section and / or dried residue.
  • Supervising sample collection and monitoring sample quality and cavings.
  • ​Evaluating oil shows.
  • Adjusting well plans during or immediately prior to drilling, due to new offset data or drilling problems.
  • Close monitoring and quality control of LWD and MWD data.
  • Continual correlation of LWD data, including picking formation and unit tops.
  • Consulting the engineer on PWD data.
  • Plotting MWD data in real time using 2-D or 3-D software. Additionally, plotting data by hand / computer following established techniques.
  • Producing / adapting zonation schemes and tying them in with log data.
  • Continually assessing and predicting apparent bedding inclination changes due to azimuth changes in the wellpath and due to true bedding inclination changes.
  • Identifying faults and assessing how to regain the target or identifying an alternative target.
  • Identifying stratigraphic discontinuities on both a large and small scale.
  • Continual re-evaluation of the static or seismic model in light of new data.

  • ​Reviewing porosity and lateral migration or variability.
  • Age interpretation of strata.
  • Determining / predicting landing points.
  • Making casing picks (and adjusting to casing / liner tallies)

  • Making coring picks and supervision, description and packing of core samples.
  • Interpretation of exploration wells to confirm structures identified on seismic data.

  • Evaluating gas data and real-time analysis of Wetness Ratio (Wh), Balance Ratio (Bh) and Character Ratio (Ch) to evaluate fluid content.

  • Identifying gas-oil and oil-water contacts or potentially partially watered out reservoirs.

  • Monitoring down-hole mud losses.

  • Monitoring drilling parameters.

  • Ensuring everything runs smoothly, e.g. back-up tools available, correct plan is followed, calibrations done, requirements followed, issues communicated, etc.

  • Supervision, correlation and quality control of wireline services to test cement bonding (USIT, CAST, CBL, VDL, IBC).

  • Supervision, correlation and quality control of specialist geological wireline or TLC services (e.g. FMI, PPC, PEX, MSIP, ADT, CMR, AIT, HRLA, GR).

  • Supervision, correlation and quality control of TLC MDT & XPT pressure testing, pump-out, sampling and leak-off tests.

  • Supervision, correlation and quality control of wireline or TLC perforation jobs (safety checks, checking guns & GR-CCL (UPCT) correlation).
  • ​​Liaising closely with directional drillers, drilling engineers and company representatives.
  • Communicating data in pre-spud meetings, morning meetings and at key points during drilling.
  • Timely production of high quality daily reports during drilling, final wellsite reports / end of well reports and geological contributions to the well specific program.
  • Assessment of learning points to build on success.
  • ​Completing Key Performance Indicator forms and evaluation forms to gauge the success of the job, timings and safety aspects.
  • Training for wellsite workers and geoscientists.
  • PowerPoint and poster presentations to communicate ideas and learning points.
  • Actively making an input into Health, Safety, Security and Environment.