Case Study: Test, Sample, and Analyze in Extremely Harsh H2S and CO2 Environments

Challenge: Conduct first-ever downhole testing program in the hazardous Arab formation reservoirs in Abu Dhabi.

Solution: Have multiple Schlumberger product and research centers collaborate on a comprehensive client-led initiative.

Result: Accomplished all objectives, and there were no lost-time incidents.

ADNOC needed testing and sampling data that had previously been considered too dangerous to acquire

Although the gas in many Middle East fields is deeply buried and heavily laced with toxic H2S, its development is considered essential to fuel electricity generation, support heavy industry, and supply a feedstock for petrochemicals. A giant gas field was selected by the Abu Dhabi National Oil Company (ADNOC) for a pilot program to study the technical challenges involved and determine the feasibility and economics of producing the extremely sour gas.

The primary test objectives for the 2008/9 well were to obtain reliable and representative fluid composition and PVT data, including concentrations of hydrocarbon gases, associated condensate yields, H2S, and CO2, in the northern area of the field. These data would be used for facilities design and well control in the hazardous Arab formation reservoirs.

A global Schlumberger team designed and conducted the requisite program

Preparation for the first reservoir test in such conditions required close cooperation and extensive preplanning with the ADNOC-ConocoPhillips joint-venture team, the drilling operator ADCO, and the other client contractors involved. Multiple Schlumberger product and research centers collaborated on a client-led initiative to address the technical challenges of the sour environment, ensure safer operation throughout all project phases, select equipment, andĀ  draw on the related experiences of experts from more than 20 countries.

Applying the Schlumberger hazard analysis and risk control (HARC) system helped manage operational risk. Well-designed and -conducted subsurface and surface sampling programs enabled thorough wellsite chemistry and laboratory fluid analyses that delivered the fluid composition and PVT data desired.

All client objectives were met without a single safety incident

After extensive due diligence, all phases of the operation were executed with zero lost-time incidents, and all sampling and testing objectives for the 2008/9 well were achieved.

Fluid samples from the successful downhole testing program, along with a comprehensive set of surface-combined and MDT modular formation dynamics tester samples acquired by Schlumberger, have significantly helped the joint-venture team optimize the development well target locations.

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