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Decision Support System for Produced Water
Management in the Offshore Petroleum Industry
Niaz Mohammed, Tahir Husain, Neil Bose, Brian
Veitch, and Kelly Hawboldt
ABSTRACT
DISSPROWM database has been designed to include
all important entities related to produced water
management. The database model is shown in Figure
2. The database model has been normalized to
third order form (3NF) to eliminate redundancy
and to improve data consistency and future
enhancements. Apart from the pollutants and
pollutant properties, information on existing
treatment technologies, their applicability and
cost in the offshore environment, information on
the regulatory requirements of produced water
discharge, and monitoring requirements have also
been introduced. The database has been
implemented on a Microsoft SQL Server 2000
database server.
DISSPROWM can assess carcinogenic and
non-carcinogenic risk to human health and marine
species. It compues individual hazard quotient
and the total fish hazard. DISSPROWM can also
assess human risk from contaminated fish
consumption as shown in the Figure 8. DISSPROWM
can not compute hazard of related to
non-carcinogenic pollutant if the reference dose
(RfD) is not available. In case of carcinogenic
risk, Slope Factor (SF) is needed. To determine
the level of risk NOEC and LC50 is needed.
Therefore risk and hazard computation will be
incomplete if DISSPROWM does not have these
pollutants stored in its database.
DISSPROWM is an integrated modeling system for
prediction of fate of produced water pollutants
in offshore environments, for determining the
best treatment technology and for assessment of
risk and hazards to human and marine species from
non-carcinogenic and carcinogenic pollutants
present in the produced water including
radionuclides. It consists of a Windows based
Graphical User Interface (GUI) developed with
Microsoft Visual Basic that integrates a SQL
Server database, an initial dilution model, a
dispersion model and risk assessment modules for
human beings and marine species. Mukhtasors
model (Mukhtasor, 2001) is used as the initial
dilution model and is good of uniform flow only.
USEPA Cormix has been used for uniform as well as
non-uniform or stratified flow. The database
contains hundreds of pollutants and their
properties that are required in dispersion and
risk assessment modeling. The database also
contains current produced water regulations and
information on some of the selected existing
treatment technologies with typical cost data
required for decision-making purposes.
INTRODUCTION
Figure 8 Computation of human carcinogenic risk
Figure 4 Main Screen of DISSPROWM showing
Pollutant Toxicology Data
According to the International Association of Oil
and Gas Producers (OGP 2004) report, about 17
million cubic meters of produced water is
produced daily worldwide in combined onshore and
offshore operations. Management of this huge
volume of produced water in offshore developments
in conjunction with the crude oil and natural gas
is a challenge for the industries. Common
disposal options include produced water treatment
(PWT), reinjection (PWRI) and disposal (PWD). It
is very difficult for the oil and gas industries
to make a decision about which disposal options
to use because this necessitates a detailed study
of treatment methods, costing information and
regulatory requirements.
Fate and Transport of Pollutants Fate and effect
of produced water depends on the fate of the
individual components and how their
concentrations change with time. Dilution is
mainly thought of as occurring in two phases.
There is the initial dilution or near-field phase
which occurs in the first few minutes, and the
far dilution phase that happens several hours
later. Fate of pollutants in DISSPROWM is
predicted by Mukhtasors initial dilution model
and Cormix. Mukhtasors initial dilution model is
used to predict the concentration at the end of
the Control volume. The model is very simple and
reportedly function with reasonable accuracy for
stable discharge from an open- ended outfall into
unstratified running water. Cormix is used for
uniform and non-stratified flow and the
concentration of pollutants is predicted at both
near fields and far-field. Mukhtasors model is
used to predict predicted environmental (PEC)
concentration and hence the exposure
concentration. PEC is computed with the
centerline dilution model proposed by Mukhtasor
(2001). Exposure concentration is computed using
the PEC, exposure probability and bioavailable
fraction. DISSPROWM has a number of tabular and
graphical option for display of PEC predicted by
Mukhtasors model and Cormix in the near field
and far field. A 2D plot for near field
concentration of one of the pollutants (Benzene)
is shown in Figure 5.
Produced Water Treatment Technologies Numerous
studies have been done on treatment technologies,
their applicability, advantages, disadvantages,
cost, commercial applications and other factors.
Information on produced water treatment
technologies are scattered and is being
continuously compiled in the DISSPROWD
database Several other commercial treatment
methods are available in the market. Most of
these treatment technologies are stored in the
DISSPROWM database. A DISSPROWM screen showing
the best available technology and alternate
technology is shown in Figure 6.

• Decisions that industries need to make are
• How clean should the produced water be before
  being discharged?
• Should the produced water be treated? If so
  what is the best available technology (BAT) for
  treatment?
• What are the alternative treatment technologies
  considering cost and removal?
• Should produced water be re-injected into the
  wells?
• What is the risk involved to the marine
  organisms and humans if the produced water is
  discharged into the ocean in the short term in
  the long term?
• What are the regulatory requirements before
  discharge and are they realistic and sufficient?

Figure 2 Database model of DISSPROWM
DESCRIPTION OF DISSPROWM

• DISSPROWM has the following characteristics and
  functionalities
• DISSPROWM is an integrated modeling system
  consisting of a SQL Server based database, an
  initial dilution model, a dispersion model
  (Cormix) and some risk assessment modules. The
  database contains produced water contaminants,
  treatment technologies, case studies, costing,
  and regulatory guidelines
• The Graphical User Interface (GUI) of DISSPROWM
  is equipped with structured menus and modern
  toolbar for frequently used functionalities and
  context sensitive Help System.
• It has interactive data entry for produced water
  contaminants and dispersion model parameters.
• It has a number of 2D and 3D graphical and
  tabular display options for displaying prediction
  of fate and transport of pollutants
• It can assess risk and hazard for fish and other
  marine species as well as human being from
  consumption of contaminated fish.
• From a known concentration of produced water
  contaminates the system can decide the best
  available technology (BAT), and its approximate
  cost. Based on the extent of treatment, it is
  possible to estimate risk to fish and marine
  species and human beings and hence a tradeoff
  between cost and risk can be developed.
• It takes series of user input in sequence and
  decides the best available technology and risk to
  marine habitats and human health as shown in
  Figure 3.

DISSPROWM is developed with the objective to
address issues that are critical for the offshore
petroleum industry and also to make the tool
applicable to industry in their decision-making
to manage produced water in a cost effective and
environmentally safe manner. A schematic of
DISSPROWM is shown in Figure 1. As shown in the
Figure, it contains a comprehensive database with
information on chemical properties, toxicity and
technology, dilution models, as well as
information on best available treatment
technology applicable to offshore platforms.
Figure 8 Treatment Technology suggested by
DISSPROWM
CONCLUSIONS AND RECOMMENDATIONS
A valuable tool for prediction of fate of
produced water pollutants in offshore
environments, for determining the best treatment
technology and for assessment of risk and hazards
to human and marine species has been developed.
DISSPRWOM is very simple, but very easy and
powerful The features of DISSPROWM include a rich
and expandable database, integrated dilution and
dispersion model for contaminant fate and
transport, integrated risk assessment tools, high
quality graphical display of pollutant dispersion
and online extensive help documentation for all
level of users. The successful use of DISSPROWM
will depend on the completeness of its database
and the authors are continuously upgrading
database for new pollutants and toxicology data,
new treatment technology and costing information.
Acknowledgement The authors acknowledge the
financial support from PRAC/NSERC CRD project.
DISSPROM can also plots contaminant plume and
Contour plot of using Surfer for Windows that
must be installed in Users PC. DISSPROM has a
user interface for various options of the
contouring, such as selection of pollutant,
setting a title for the contour plot, smoothening
of contour, shading of contour and using a
boundary file overlaid on the contour plot. A
contour plot is shown in Figure 6.
Figure 3 The Schematic of DISSPROWM
DISSPROWM force users to enter different
categories of input data in a sequential manner.
The Sequence data should be entered is shown on
the Tabs below the toolbar. After the project
information is entered, other categories of data
are entered or computed in the following
sequence Pollutant name ? Pollutant
Concentration ? Flow and Ambient data ? Control
Volume Data ? and Fish Data ? risk computation
data. The structure of the system that showing
pollutants toxicology data is shown in Figure 4.
This data is retrieved from database. Users are
required to estimate and enter the missing data
so that Risk and hazard can be computed by
DISSPROWM. Upon completion of data entry,
DISSPROWM allows user to save the data in a
project file and perform different task. Some of
functionalities of DISSPROWM, such as querying
database entries and generating reports can be
done any time without competing data entry.
Figure 1 Structure of DISSPROWM
DISSPROWM DATABASE
References Chowdhury, S. H. (2004). Decision
Support System for Produced Water Discharges in
Offshore Operations, MS Thesis, Faculty of
Engineering and Applied Science, Memorial
University of Newfoundland. Mukhtasor (2001).
Hydrodynamic modeling and Ecological Risk Based
design of produced water discharge from an
offshore platform A thesis for PhD at Memorial
University of Newfoundland. OGP, (2004). Fate and
effects of naturally occurring substances in
produced water on the marine environment - a new
review, Draft sent to OSPARs meeting of the
offshore industry committee (15-19 March 2004,
Agenda item 3, OIC 04/3/Info.1-E) by The
International Association of Oil and Gas
Producers (OGP).
Numerous studies have been conducted in the past
on produced water contaminants, their fate and
transport in the marine environment, risk induced
to the ecology and human beings. These studies
has been compiled in many books and reports.
Chowdhury (2004) developed a Microsoft Access
based database that contains common produced
water pollutants and their properties.