Page 165 - Environmental Control in Petroleum Engineering

152 Environmental Control in Petroleum Engineering

total volume and/or the toxic fraction of wastes generated. The primary
waste minimization activities are to make changes in how chemical
inventories are managed, how operations are conducted, which materials
and chemicals are used, and how equipment is operated.
The advantages of waste minimization include avoidance of waste
transportation and disposal costs, elimination of expensive pollution
control equipment, improved product quality, less administrative
recordkeeping, lower on-site handling costs, a smaller waste storage
area, reduced waste and tax obligations, improved public image, lower
potential environmental impacts, and reduced future liabilities.
Unfortunately, the opportunities to significantly reduce the volume
of drilling and production wastes are limited. The greatest volume of
waste is produced water, which is controlled by the age and production
history of the field. The volume of drilling wastes is controlled primarily
by the depth and number of wells drilled. Nevertheless, many opportuni-
ties are available for minimizing wastes and have been described in
the literature (Hall and Spell, 1991; Savage, 1993; Thurber, 1992;
Wojtanowicz, 1993a and 1993b).

Inventory Management

One aspect of waste minimization is to carefully monitor inventories
of all materials at a site. Accurate, written records of all raw and
processed materials and their volumes should be kept for every stage
of handling and production. The costs of each material, including
disposal, should also be recorded.
Better management of materials inventories provides significant
environmental benefits. It allows a material balance to be conducted
on all materials at all stages of usage. A detailed material balance can
help identify where unwanted losses and waste may be occurring.
From a better understanding of actual needs of different materials, the
volumes of chemicals purchased may be reduced. Keeping excess
chemicals in stock increases both the cost and the chance of spillage
or leakage. Accurate records also allow chemicals to be rotated so that
their shelf life does not expire before they are used. If large volumes
of a chemical are needed, it can be purchased in bulk to reduce the
number of containers requiring disposal. Accurate records can be used
to determine whether the volume of chemicals purchased are propor-
tional to their use and whether purchase restrictions are needed.