Page 13 - Environmental Control in Petroleum Engineering

2 Environmental Control in Petroleum Engineering

1.1 OVERVIEW OF ENVIRONMENTAL ISSUES

Finding and producing oil and gas while minimizing adverse environ-
mental impact requires an understanding of the complex issues facing
the upstream petroleum industry. These issues concern operations that
generate wastes, their potential influence on the environment, mech-
anisms and pathways for waste migration, effective ways to manage
wastes, treatment methods to reduce their volume and/or toxicity,
disposal methods, remediation methods for contaminated sites, and all
applicable regulations.

1.1.1 Sources of Wastes

Wastes are generated from a variety of activities associated with
petroleum production. These wastes fall into the general categories of
produced water, drilling wastes, and associated wastes. Produced water
accounts for about 98% of the total waste stream in the United States,
with drilling fluids and cuttings accounting for the remaining 2%.
Other associated wastes combined contribute a few tenths of a percent
to the total waste volume (American Petroleum Institute, 1987). The
total volume of produced water in the United States is roughly 21
billion barrels per year (Perry and Gigliello, 1990). A typical well can
generate several barrels of fluid and cuttings per foot of hole drilled.
In 1992, 115,903,000 feet of hole were drilled in the United States
(American Petroleum Institute, 1993), yielding on the order of 300
million barrels of drilling waste.
Produced water virtually always contains impurities, and if present
in sufficient concentrations, these impurities can adversely impact the
environment. These impurities include dissolved solids (primarily salt
and heavy metals), suspended and dissolved organic materials, forma-
tion solids, hydrogen sulfide, and carbon dioxide, and have a defi-
ciency of oxygen (Stephenson, 1992). Produced water may also contain
low levels of naturally occurring radioactive materials, or NORM
(Gray, 1993). In addition to naturally occurring impurities, chemical
additives like coagulants, corrosion inhibitors, emulsion breakers,
biocides, dispersants, paraffin control agents, and scale inhibitors are
often added to alter the chemistry of produced water. Water produced
from waterflood projects may also contain acids, oxygen scavengers,