Using Stream Sampling and a Helicopter Electro-Magnetic Survey to Locate Oilfield Brine Sources Affecting Streams

Patricia Billingsley and Bruce Smith
Oil and Gas Conservation, Pollution Abatement, Oklahoma Corporation Commission, Oklahoma City, OK

The Oklahoma Corporation Commission began monitoring streams in old oil and gas fields in 1997. By 2002 we know that the three main streams (Upper Caddo Creek, Wildhorse Creek, and Rush Creek) in a 1,000 square mile area in south-central Oklahoma were salinity impaired. Area produced water has chlorides up to 100,000 mg/l.

Questions needing answers were: Was there extensive area pollution from many saline sources, or only a few sources affecting many miles downstream? What types of sources? Where?

By sampling streams wherever a county or state road crossed a stream/tributary, it was determined that Rush Creek is mainly affected by a few upstream tributaries in one oilfield. However, about thirty separate streams and tributaries were salinity impacted in the Caddo and Wildhorse watersheds, leaving over 300 square miles that had to be searched for salinity sources, many not apparent at the surface.

Possible sources include:

Discharges to streams due to accidents, poor maintenance, and (rare) illegal actions,

Eroding saline soil from historic to recent spills and mud pits,

Groundwater plumes (seeps, springs) from old mud and pre-1970 “evaporation” pits, and

Groundwater plumes from producing wells, improperly plugged abandoned wells, and/or injection wells that leaked into shallow aquifers.

To speed up salinity source type identification and source location, we funded a test of the USGS developed Helicopter Electro-Magnetic Survey on 25 square miles where there are many saline streams. This presentation will summarize the streams impacted; outline the HEM methods used; and show the HEM survey results, including maps and frequency data or cross-sections.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas