PRODUCED WATER TREATMENT AND REUSE IN QUEENSLAND, AUSTRALIA. Introduction

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1 PRODUCED WATER TREATMENT AND REUSE IN QUEENSLAND, AUSTRALIA Ronald M. Cass, P.E., PMP, MWH Americas, Inc North Central Expressway Suite 1140 Dallas, Texas Michael Bremer, Origin Energy, Brisbane, AU Ryan Goostrey, Origin Energy, Brisbane, AU Introduction Queensland s Bowen and Surat Basins are expected to provide a major supply of natural gas to Australia s eastern states and to produce natural gas for liquification and export to customers throughout Asia Pacific. Coal Seam Gas (CSG) is a natural gas occurring in underground coal seams, and is usually most productive between 200 and 1,000 meters below the surface. It is held in the fractures of underground coal seams by water and ground pressure, and released by drilling into the coal seam and reducing the pressure by pumping out some of the water. The efforts for development in Queensland include: Drilling of thousands of wells for water/gas extraction Collection and separation systems Gas compression and pipeline to liquification facility on Curtis Island, along the central Queensland coast. Produced water treatment and reuse The Bowen and Surat basins are located in the state of Queensland in the northeast quadrant of the Australian continent. The collection fields are approximately 400kM inland from the liquefication facility on Curtis Island. Energy developers in this area include: Queensland Curtis LNG (QCLNG) - owned by the Queensland Gas Company QGC (a BG group company) Gladstone LNG (GLNG) - a joint venture between Santos Ltd, Petronas, Kogas and Total Australia Pacific LNG (APLNG) - a joint venture project between Origin, ConocoPhillips and Sinopec Arrow LNG - a joint venture between Shell and PetroChina Gladstone LNG Fishermans Landing - a joint venture between LNG Limited and Huanqiu Contracting and Engineering Corporations HQCEC (a wholly owned subsidiary of China National Petroleum Corporation) 1

2 Figure One Queensland s Coal Seam Gas Overview (February 2012) 2

3 Purpose The purpose and focus of this paper is to discuss the options for treatment of the produced water fraction from the gas/groundwater separation for reuse. Beneficial reuse of the treated, produced water is highly desirable as providing an improvement function to the development. The primary goal of the treatment scheme is to receive and treat all well development water at a rate not to inhibit extraction, and to a quality to allow reuse for a variety of purposes: Industrial Reuse such as cooling water that would normally be taken from area streams or groundwater Agricultural Reuse reuse in lieu of further groundwater extraction, extending preservation of the local aquifers Injection a groundwater replenishment initiative River Discharge blending with the seasonal ephemeral stream to eliminate aquatic impact. This paper is not intended to delve into the technologies associated with coal seam gas extraction which creates the feed water. Nor will this discussion include the brine stream disposal component of the water treatment train. Background Coal seam gas is a naturally occurring methane, captured in seams of underground coal and most frequently occurs in seams between 200 and 1000 meters deep. Most of the gas is dissolved within the groundwater due to the tremendous pressure of the overlying water table. As the groundwater is removed and the pressure reduces, the gas and water separate. The groundwater and dissolved gas is only pumped long enough to reduce the pressure, allowing the gas to be free flowing. Figure Two Typical Extraction Well After gas separation, the water quality is typically: Brackish saline mg/l TDS Hardness mg/l (Bicarbonate, predominantly) Iron and Manganese contributions Silica mg/l. The nature of the gas field development does not allow for variable downstream demand of treated water. Unlike traditional water treatment facilities, the rate of treatment is based upon feed water rate, generated from the extraction and separation processes. Any limitation on water treatment, in turns limits the extraction of gas, the financial driving force of the development. The reuse components of a project such as this require alternatives that can be utilized when there are limiting factors on the reuse application. For 3

4 example, if the water treatment discharge was limited solely to one industrial re-user, the impact of a shutdown of that facility would suspend all coal seam gas production for that region. Clearly, multiple reuse alternatives are needed to minimize the risk of production loss due to limiting discharge. The treatment options are dependent upon the reuse options and the ability of the reuse option to absorb the produced flows. As design often progresses, the treatment trains often applied to these circumstances allow for full plant production using the worst of feed water quality, combined with the most stringent of the discharge water quality restrictions. Treatment Alternatives The amount of water produced during gas extraction is difficult to predict and varies both with the location and stage of the production cycle. Likewise, the quality of the associated water is highly variable, but it frequently contains elevated quantities of salt and bicarbonate. A range of treatment techniques have been considered and applied, to achieve reuse and discharge water quality objectives. Primarily this effort is comprised of four stages: 1. A feed pond to provide a required holding time, buffer storage, aeration and release of free gases, and stability of temperature 2. Pre-treatment technologies to remove solids and condition water for desalination processes 3. Desalination comprising the use of reverse osmosis and distillation 4. Combined permeate and distillate chemical stability. Groundwater degas is used at the wellhead to separate water from the gas. As the pressure is relieved, the gas in the flow stream is released from solution. It is at the wellhead that there are two flow streams then created, one for separated gas and one for water. The water flow stream is considered produced water, and a by-product of the gas extraction. It is this flow stream that gets collected and transported by a pipeline network to one of the water treatment plant sites. As this flow stream arrives, it is discharged into an atmospheric reservoir or pond. Since the water still contains some remaining gas and other easily stripped constituents such as iron, a cascade structure has been provided to aid in the removal. Filtration is applied in a regulated flow to the treatment facilities in two steps. First, a gross filtration step of 4 micron is applied for the removal of any algae, precipitates or contaminants from the open water surface of the pond. Then membrane filtration is used for the removal of any remaining fine particles to prevent interferences and damage on downstream processes. Softening is used in the form of ion exchange to reduce bicarbonate and condition the water to enhance downstream reverse osmosis performance. A reduction of hardness (predominantly in the form of bicarbonate and related total dissolved solids) results in less scaling of the RO membranes due to brine concentration. This allows the RO system to operate at higher recoveries and improve efficiency. Subsequently, single pass reverse osmosis desalination is utilized on the brackish water to reduce salt content and maximize reuse options. Distillation is used on the brine stream to further concentrate the brine, increase recovery and as the main driver, reduce the total volume of the waste stream. 4

5 The treatment results in up to four streams; a treated low salinity stream or permeate for reuse the chemical waste stream (to be transferred and stored in lined effluent ponds); a brine stream; and a dewatered solids waste stream With no allowed discharge of any of the waste streams, they are stored in a holding pond, having further concentration before being hauled off for disposal. The remaining low salinity stream is quite low in ions and hence requires stabilization through the addition of calcium and magnesium. To minimize chemical use, a small amount of MF filtrate is blended to the stream, reducing the amount of chemicals required to stabilize the water. It is this adjusted permeate stream that is the focus of reuse alternatives. Reuse Alternatives The Queensland Government has established guidelines for preferred and non-preferred management option for coal seam gas water under the Environmental Protection Act Category One preferred management options include: Aquifer injection where detrimental impact is unlikely (includes virtual injection ) Untreated use where detrimental impact is unlikely Treatment to an agreed standard for agricultural, industrial and potable uses Category Two non-preferred management options include: Disposal via evaporation dams Disposal via injections where detrimental impact is likely Disposal to surface waters Disposal to land The Queensland Government provides a guideline for approval of coal seam gas water for beneficial use, noting A beneficial use approval changes the status of the material from a waste to a resource that can be used for a beneficial purpose. DERM (Department of Environmental and Resource Management) will issue notices of decision to approve a resource for beneficial use for CSG water for the following uses: Aquaculture Coal washing Dust suppression Industrial use Irrigation 5

6 Livestock watering For these facilities, an export handling system receives all treated water streams (permeate and distillate) and blends, and stabilizes to produce up to four finished water quality streams, each for different purposes of reuse: Injection a groundwater replenishment initiative, to re-inject treated water back into the aquifers. This approach under DERM, requires a feasibility study, investigating the aquifer characteristics to offset the impacts from CSG extraction. This also considers virtual injection, where an approved beneficial use substitutes an existing groundwater take. Industrial Reuse Industrial and manufacturing use is likely to be quite varied, and treatment is clearly dependent upon end use. With these water treatment facilities centralized in a remote region of many hectares of well extraction fields, there are few opportunities at this time for industrial reuse. Our project applications include vegetation irrigation to reduce erosion of embankments, service water for dust control, washdowns and camp use. Agricultural Reuse Agricultural reuse is gaining interest in the region with trials of Pongamia pinnata a type of legume that can be used as cattle feed and can also be processed to make biofuel. This potential biofuel has been under world-wide scrutiny o for ease of growth and oil production on marginal lands and with saline water sources o petroleum based fuel independence and o Sustainability. Research is an ongoing interest of the academic community in Queensland, with many potential applications under consideration. River Discharge River discharge is the last and final option declared as non-preferred by DERM. As can be imagined with most sensitive watersheds and water ways, issues of concern are inter-basin transfer, water quality and temperature change impacts on aquatic life, and percentage of discharge flow to stream base flow. With climatic conditions and potential restrictions, this is likely the most difficult criteria to achieve, recognizing the stream seasonal and diurnal variations. Project Delivery The Project includes various components - extraction wells, gas/water separation systems, independent gas and water collection systems, regional gas compression facilities, regional extraction water treatment and reuse plants, and gas pipeline system to a liquification facility all constructed under various contracts. Each of these contracts were completed under Engineer, Procure, Construct (EPC) methods, wherein the Origin Energy design team prepared, and the procurement team bid, secured and managed the supply of all process treatment equipment. The design team prepared civil, structural, electrical, mechanical, instrument and control requirements for each contract. The Construction Contractors for the Gas Facility and then another for the Water Treatment Facility were selected on a balanced combination of bid cost at a 90% completion of design, combined with qualifications of the Company, and individual key staff. 6

7 One of the challenges anticipated at the start of the project was rapidly integrating an Origin Energy owner s team who had been working on the Front End Engineering Design for just under a year separately from an MWH consultant s team who had commenced involvement during the later stages of FEED completion. It became apparent during the FEED completion that a high degree of interaction between owner and consultant teams would be required to maintain the project schedule. This was further exacerbated by the involvement of the Early Contractor Involvement (ECI) Contractor, Enerstream JV. All the parties jointly agreed to co-locate at MWH s offices at commencement of detailed design. Immediately steps were taken to Brief the co-located team on the scope jointly review of scope, unpacking and repacking the project to ensure all key staff are across the content and requirements of the project. Staff from owner s team, consultant lead engineers, procurement and construction were located close to each other as soon as possible. Concepts such as modularization of the main pipe racks were disseminated quickly through the team to ensure the key senior staff were enrolled in the reasoning and benefits behind these principles. Review and communicate values alignment of each organization in the context of the project, to maximize alignment to project goals Teambuilding both formal and informal ensuring that staff got to know each other before they started working together to ensure that they had as solid a relationship as possible on which to found their working relationships. In addition the team fostered an open culture of identifying and resolving issues early, escalating these to the co-located management team where appropriate. Alignment of cultures, discussing methodologies and avoiding the trap of here s how we did it on the last project. A good example of this was the time spent developing the Ponds Design Plan incorporating MWH knowledge and Origin experience into a coherent document. Underpin all this with appropriate Systems and processes kept simple and in particular to ensure adequate scope management (learning) and management of change Selection of personnel to work in a collaborative environment is crucial not sufficient to have the right technical skills lead engineers in particular need to be proactive, knowledgeable and able to quickly build relationships and trust. Support was given to areas where staff were having difficulty adapting and changes were made where it was clear alignment was not being achieved. Project outcomes can be enhanced by careful attention to project culture, project planning and collaborative working. Awareness between all parties that there are differences between engineering requirements for water treatment plants and gas plants is critical to project success. Alignment between the owner, engineering and contracting teams is critical for project success. Looking Forward The reuse side of the CSG development is in its infancy, yet presented with many challenges. In the face of vocal opposition, regulators are rightfully cautious and concerned with unpredicted effects. Developers and operators are challenged with arguable and conservative criteria. As this drive for clean energy and development of new alternatives for extraction are considered, there will be more information available 7

8 upon which to evaluate impacts. Development and monitoring of production water, along with accurate projections of quality and quantity are essential for creating good treatment design approaches and broader a consistent global application of technology. 8