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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 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. Mukhtasor’s 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. 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 it’s database. INTRODUCTION 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. 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? 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 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. 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 Mukhtasor’s initial dilution model and Cormix. Mukhtasor’s 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. Mukhtasor’s 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 Mukhtasor’s 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. Figure 8 Computation of human carcinogenic risk 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. Figure 8: Treatment Technology suggested by DISSPROWM CONCLUSIONS AND RECOMMENDATIONS DISSPROM can also plots contaminant plume and Contour plot of using Surfer for Windows that must be installed in User’s 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 Figure 1: Structure of DISSPROWM DISSPROWM DATABASE 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. POSTER TEMPLATE BY: www.PosterPresentations.com 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. 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 OSPAR’s 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).