FINGERPRINTING FORMATION-WATERS USING STABLE ISOTOPES AND OTHER NATURAL TRACERS: APPLICATIONS TO PETROLEUM EXPLORATION, DRILLING, AND PRODUCTION

During petroleum exploration, drilling, and production operations, produced fluids are often recovered. Numerous questions regarding the origin of produced fluids arise, questions that have historically been addressed using a variety of water chemical techniques (e.g., dissolved element “stiff” diagrams). However, standard chemical fingerprinting techniques can be problematic or ambiguous, especially when working in environments with evaporites (hence brine formation-water), or in shallow (fresh formation-water) settings, or in areas with little-known formation-water fingerprint(s).

Fingerprinting techniques using stable isotopes and other natural tracers in formation-waters have been developed that overcome many of the problems with previous methods. Over the past 15 years, these techniques have been used repeatedly by the oil industry in Western Canada and abroad, in a variety of exploration and production operations, including:

1) During Drill-Stem-Testing and swabbing operations to determine if recovered fluids are pure formation water. This can prevent costly errors such as improper reserve estimation, or premature well abandonment.

2) As a production monitoring tool, to determine if produced fluids are originating in the perforated zone (versus migrating from “out of zone” into the wellbore from other formations). Repairing wells producing “out of zone” water can extend their life.

3) As a waterflood monitoring tool.

4) Tracking water generated during the stimulation of horizontal wells targeting comparatively thin pay zones of low permeability (e.g., hydraulic fracturing in the Bakken Formation).

5) As an aid to exploration, by enhancing understanding of reservoir continuity.

This presentation will review fingerprinting techniques using stable isotopes and other natural tracers using a number of examples from petroleum operations in the Williston Basin (Canada-USA).