Wellsite Geology

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Wellsite Geologist Function

The Wellsite Geologist is responsible for obtaining the maximum amount of subsurface information possible under prevailing drilling conditions and describing and evaluating all hydrocarbon shows utilizing the tools available.

The Wellsite Geologist has the responsibility of achieving the objectives set forth in the Drilling Program. The geologist's responsibilities include:

· Ensuring compliance with all safety, health and environmental procedures and guidelines

· Achieving the geological objectives set forth in the Drilling Program

· Supervising Geological Service Company personnel including:

Ø Data Engineers and Mud Loggers (Mudlogging service)

Ø Logging While Drilling (M/LWD service)

Ø Wireline Logging

Ø Core handling Personnel

Ø Geochemistry/Biostratigraphy if at wellsite

· Description of ditch and core samples

· Interpretation of hydrocarbon shows

· Core point selection, core handling and description

· Casing point selection (together with Drilling Supervisor)

· Daily reports to main office and dispatch of data

At the rig, the Wellsite Geologist will receive reports and data from the geological contractors such as mudlogging and LWD etc. These data, together with the Wellsite Geologists’ own reports and log will be organized and sent to the Operations Geologist. The Wellsite Geologist will also keep the Drilling Supervisors informed and advise them of the progress of geological operations.

The Drilling Supervisor will pass on information to the Wellsite Geologist pertinent to the drilling operations and he will also report on drilling activities to the Drilling Superintendent

The Wellsite Geologist is the main conduit of geological information from the rig, reporting to the Operations Geologist. It is vital that communication lines are kept open between all parties. The daily reporting procedures have been set up to ensure that there are platforms for proper reporting and communication.

In turn, information regarding upcoming operations and changes to the well plan should be passed back down the hierarchy from Operations Geologist, through Wellsite Geologist and on down to geological contractors. Daily rig meetings where representatives of all contractors are present provide a useful forum for communication.

Geologist going to the wellsite should be familiar with the Drilling Program for the proposed well which consists of:

· Well design

· Well objectives

· Shallow hazards

· Sampling program

· Coring program

· Logging programs

· Lithostratigraphy

· Formation Pressures

HTHP Wells

If a High Pressure - High Temperature (HPHT) well is to be drilled then there may be a more formal familiarization process where all the geoscientists involved may meet to review wellsite procedures and discuss important aspects of the well. The Wellsite Geologist’s prime resource will be the Operations Geologist and Drilling Program which should provide all the necessary information regarding the well. Other resources will be:

· The Site Survey - the summary of the shallow geology and the likelihood of shallow gas.

· The Wellsite Geology Guidelines and Procedures

· Formation Pressure Review - a regional study of formation pressures may have been carried out. This will give detailed information regarding regional pressure trends.

· Offset well logs - Composite logs from nearby wells can give an idea of expected geology. Well reports can also be useful.

What is Mudlogging?

Mudlogging is the collection and analysis of gas and geological data that come from the wellbore. It is the first tier of formation evaluation. Mudlogging services include the collection and in-depth analysis of formation cuttings, as well as the collection and interpretation of gas data. Mudlogging data can unlock more insight into what is going on downhole.