Enhanced oil recovery processes, particularly offshore, create challenges for produced water treatment. Higher oil prices has created increased interest in chemical enhanced oil recovery (CEOR) using polymers, surfactants, and alkalis. This technology poses some special challenges, especially around water treatment.
Produced water from chemical floods can cause problems for separation and water treatment equipment due to the polymers and surfactants used. Challenges are greater offshore where space limitations can affect treatment options. A variety of low-cost technologies can result in an increase in production in mature oil and gas fields, although the increase is usually temporary and not always economical.
In the complete paper, three stages of review have been combined to find out the applicability of the most-feasible improved-oil-recovery (IOR) methods in North American unconventional reservoirs. The US Energy Information Agency reports that the country is seeing petroleum exports rise across the board and notes serveral drivers for this trend. This paper describes functional water-treatment steps that target the most common removal of suspended solids and oil or condensate from Produced-water (PW) and flowback-water (FW) for recycling or disposal operations.
Aker Solutions and FSubsea have agreed to a joint venture, named FASTSubsea, to help operators increase oil recovery. High-concentration polymer flooding can improve oil-displacement efficiency but separation of oil/water mixture becomes more difficult because of emulsification. In this work, a case history of dehydration technology for HCPF production and lab investigation of emulsion behaviors are reviewed. The authors discuss the results of a pilot project to capture post-combustion CO2 for purposes of EOR. Produced water from chemical floods can cause problems for separation and water treatment equipment due to the polymers and surfactants used.
Water from the reject stream of the Reverse Osmosis (RO) units in Sulaibiya Waste Water Treatment plant (SWWTP) will be used as source water for the Once-Through Steam Generators (OTSG) for the South Ratqa (SR) Phase I project. Using sewage water as source water for steam boilers directly impacts the complexity of the water treatment processes.
Based on the South Raqa steam quality specifications, a water quality requirement has been defined which was found in line with international guidelines. For one of the quality requirements specified (Chemical Oxygen Demand) a tight specification of < 0.1 mg/l was set, which is not often seen in the industry. Instead the industry does define Total Organic Carbon (TOC) as water quality specification, which is closely related to COD. As the water source in the Sulaibiya is coming from a sewage plant (unknown organic components), COD was included as water quality specification.
To deliver the required BFW quality, seven different treatment steps are being installed, which all need to be optimised to ensure the required high plant availability. The major risk area is the requirement to achieve residual chlorine in the water stream coming from the Sulaibiya plant.
Reminiscent of the song made famous by late Hawaiian crooner Don Ho, tiny bubbles are the focal point of a new innovation aimed at transforming produced water from a costly byproduct into a valuable asset. Termed nanobubbles, they are several times smaller than a human red blood cell, which allows them to play with the physics of how dissolved gas interacts with liquids, according to Nano Gas Technologies. The suburban Chicago-based startup says its technology is capable of cheaply producing these nanobubbles to treat produced wastewater that is among the "worst of the worst." The technology works by pushing gas, either oxygen or nitrogen, through a nozzle head that shoots the tiny bubbles into a treatment tank. The result is what the company's chief executive officer, Len Bland, calls "fluffy water" that causes suspended solids to fall and oil to float to the top where it is easily skimmed off.
Water management has always been an important part of production operation but for chemical EOR it becomes one of the critical elements as the whole water cycle needs to be analyzed and adapted to the process. In particular one key aspect that is generally neglected concerns the impact of EOR chemicals on the produced water cycle. After the chemical breakthrough, part of the EOR chemicals (polymers and/or surfactants) will be back-produced and can induce heat exchanger fouling and strongly impact oil/water separation and water treatment surface processes. All these drawbacks may lead to skewed forecasts on economic performance of EOR projects.
Some of the key challenges with produced water treatments, that facility engineers and operators will be facing when preparing a chemical EOR project, will be highlighted in this paper. A focus on some experimental results obtained within the DOLPHIN JIP – supported by 14 oil companies – will be presented. A specific laboratory methodology dedicated to the study of the impact of ASP-type chemicals on heat exchanger fouling, oil/water separation and water treatment efficiency and which mimic actual surface processes, was designed.
Results presented will illustrate the operational conditions that favor deposit on heat exchangers when polymer is back-produced. Impact of having polymers and/or surfactant within produced fluids on oil/water separation (kinetics of separation and quality of both oil and water phases) and water treatment processes efficiency (evaluated by monitoring the concentration of remaining oil in water as a function of time) will also be outlined.
This work emphasizes that water management is a major challenge for chemical EOR that needs an integrated approach and should be studied upfront. Laboratory workflows and procedures could help the de-risking of operations and try to mitigate separation issues that could advantageously be integrated into the design of chemical EOR project.
Shidi, M (Petroleum Development Oman LLC) | Mjeni, R (Petroleum Development Oman LLC) | Qayum, S (Petroleum Development Oman LLC) | Nadeem, MS (Petroleum Development Oman LLC) | Philip, G (Petroleum Development Oman LLC) | Prigent, S (BAUER Nimr LLC)
A Surface Flow Constructed Wetland System (called a Reed bed) is used as a disposal means for produced water (PW) containing hydrocarbons in a field located in the south of Oman. The Reed bed system is a farm of plants that remove oil from water, followed by evaporation ponds where the water is evaporated.
In the same field, it is planned to undergo HPAM Polymer Flood. One of the risks envisaged with this activity was the capability of the Reed bed system to handle back produced water contaminated with polymer. Therefore, a series of tests were conducted to understand the impact of polymer contaminated produced water on the Reed beds.
The experiment was carried out in two phases with a small scale experiment in batch mode followed by a long term field trial at a full scale. The first phase aimed to introduce by batches HPAM into small Intermediate Bulk Containers planted with reeds and monitored for 5 months. It was observed that HPAM resulted in an increase in the growth rate and evapotranspiration rate in some of the plants. It was clear that the HPAM did not cause any negative effects on the plants during the short-term duration of the study and the results were very encouraging.
A long term field trial was then conducted to verify the results observed from the batch experiment. To mimic the large scale Water Treatment Plant reed bed, four pilot scale (40m × 40m) surface flow wetlands were built and planted with five types of plants similar to the plants currently available, all receiving produced water with different HPAM concentrations (0, 250, 500 and 1000ppm), 0ppm serving as a control. The trial was conducted for duration of one year. The
The success criteria evaluated in this pilot were divided into two categories with critical and non-critical criterias. A critical criteria was defined as one for which a negative outcome requires significant system modifications to process produced water containing polymer. The criterias are Oil Removal, Above Ground Dry Biomass and Necrosis. The non-critical criterias such as polymer removal, plants toxic symptoms, plants health, Acrylamide accumulation and water loss imply potential minor design modifications maybe requiredto the existing Reed Bed. These criterias were developed and assessed by the company responsible for the design, operation and monitoring of the Long Term Field Trial.
The outcome was positive for all critical criteria with the exception of plant necrosis at 1000 ppm polymer. Two plants species out of five showed necrosis in the 1000ppm wetland higher than the 0ppm wetland. The Necrosis was determined to be inconclusive at 1000ppm as there were no signs of Necrosis at 500ppm and below and other factors not related to polymer are highly suspected to be responsible for this behavior. All the non-critical criteria were highly positive except for polymer removal. The wetlands did remove some of the HPAM from the produced water but not all of it. There are some uncertainties surrounding the long-term fate of the HPAM in the system for reusing the treated produced water from the wetlands. Currently, the water is evaporated after the reed beds, however the presense of polymer in it limits any further use of that water. The positive results seen during the trials have demonstrated that there is no risk on reed beds when processing up to 500ppm HPAM.
Reminiscent of the song made famous by late Hawaiian crooner Don Ho, tiny bubbles are the focal point of a new innovation aimed at transforming produced water from a costly byproduct into a valuable asset. Termed nanobubbles, they are several times smaller than a human red blood cell, which allows them to play with the physics of how dissolved gas interacts with liquids, according to Nano Gas Technologies. The suburban Chicago-based startup says its technology is capable of cheaply producing these nanobubbles to treat produced wastewater that is among the "worst of the worst." The result is what the company's chief executive officer, Len Bland, calls "fluffy water" that causes suspended solids to fall and oil to float to the top where it is easily skimmed off. "If you want to put it in technical terms," he said, "we change the specific gravity of the liquid so that it enables the oil that is stuck in the water to rise."