21    BIODEGRADATION OF OILFIELD PRODUCTION PIT
SLUDGES
Robert E. Marks, Graduate Research Assistant
Stephen D. Field, Associate Professor
Department of Civil Engineering
Andrew Wojtanowicz, Assistant Professor
Department of Petroleum Engineering
Louisiana State University
Baton Rouge, Louisiana 70803
INTRODUCTION
This research effort seeks to develop a biological treatment for degrading the oil and grease
fractions in drilling fluids and production sludges prior to solids separation. The drilling fluids are
produced as excess waste during the development of the oil and gas resources while the production
waste sludges are generated during the production life of the oilfield. Both kinds of wastes are stored
in open, walled impoundments or pits, and solids range from 5-75% (v/v). The presence of oil and
grease in both the drill cuttings and production sludges has a severe detrimental effect on the type of
treatment and handling procedures which can be employed for disposal of these waste materials.
The State of Louisiana through the Department of Natural Resources (DNR), currently regulates
the treatment and final disposition of petroleum non-hazardous oilfield wastes (NOW) through
Statewide Order 29-B. This order permits closure of pits by burial, trenching, land treatment, solidification, and offsite disposal provided specific criteria are met.1 These criteria provide for closure
approvals of those pits which are low in oil content (> 1%, oil & grease, dry wt.) when mixed with the
surrounding soils for land treatment. Table I shows the oil & grease closure limits for disposal
methods, applicable to waste pits, by Statewide Order 29-B. Those pits which have a high oil and
grease content are not readily amenable to cost-effective waste pit closures by the above methods.
Biological treatment for the biodegradation or separation of the oil could provide either an intermediate step or in some cases be the ultimate processing step.
Both State and Federal agencies require elimination of these waste pits which contain the NOW
waste. However, the United States Environmental Protection Agency is charged with the task of
evaluating the constituents of these wastes to determine whether they should be classified and regulated under the Resource Conservation and Recovery Act (RCRA). If reclassification occurs, new
research will be stimulated towards working with these wastes for separation and destruction of the
hazardous components. A proposed ban on land disposal in the early 1990's, will increase the demand
for new technologies to treat and dispose of these oilfield wastes effectively.
Table I.   State of Louisiana Limits for Oil & Grease for Disposal
of Non-Hazardous Oilfield Wastes
Disposal Method Allowable Maximum
1. Burial or trenching
. cells 3% (Dry Wt.)
2. Land treatment
• Zone  1% (Dry Wt.)
• Runoff water  10 ppm
3. Solidification
• Leachate 10 ppm
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