Without regulation pertaining to the use and discharge of surfactant for offshore enhanced oil recovery (EOR) process in Malaysia, we adopted the guidelines from OSPAR (Oslo Paris Convention) that governs the use and discharge of offshore chemicals in the North Sea Region. In OSPAR, the CHARM (Chemical Hazard Assessment and Risk Management) model is being used to assess the risk of offshore chemicals to the marine environment. CHARM prescribes the Predicted Environment Concentration:Predicted No-Effect Concentration (PEC:PNEC) approach which ratio determines the hazard quotient (HQ) in order to rank the chemical by colour banding. Our surfactant formulation achieved a HQ of 2.16 or Silver colour banding with the stipulation that the volume of the discharged produced water is twice the volume of chemical solution (squeeze) injected. Nevertheless, in providing more certainty and confidence for both operators and local regulators to allow for overboard discharge of our flow-back surfactant formulation, we conducted a comprehensive produced water dilution modelling called DREAM (Dose-related Risk and Effect Assessment Model). The model calculates the Environmental Impact Factor (EIF) of each component of the chemical in the discharged produced water. Similar to CHARM, the DREAM uses the PEC:PNEC approach, but its PEC input parameters include environmental influences such as weather profile, current, etc. and incorporates a slick model. Its output is a quantation of the risks to the receiving environment, called the Environmental Impact Factor (EIF); where EIF is more than 1, the impact to the environment is significant. We simulated the chemical fate of individual component of the formulation with the scenario whereby the produced water is not treated prior to discharge. The time-averaged EIFs were more than 1 across all weather windows, indicating the discharge of untreated chemical-containing produced water is likely to have a localized environmental impact. We used both CHARM and DREAM as decision support tools for effective management of operational discharges from offshore projects. Limitations and recommendations from DREAM simulation results in the context of our EOR application are discussed.
Chai Ching Hsia, Ivy (Petroliam Nasional Berhad PETRONAS) | Shafie, Nur Anisah (Petroliam Nasional Berhad PETRONAS) | Razali, Norzafirah (Petroliam Nasional Berhad PETRONAS) | A Manap, Arif Azhan (Petroliam Nasional Berhad PETRONAS) | Salleh, Intan Khalida (Petroliam Nasional Berhad PETRONAS)
The application chemicals such as surfactants for Enhanced Oil Recovery (EOR) has caught the attention of various stakeholders especially regulators and operators - raising concerns of the impact of these chemicals to the ocean when they are back-produced. The current approach in mitigating the toxicity at production is the dilution of produced fluids to a lower concentration before disposal to sea. However, how confident are we that EOR chemicals do not cause environmental impact to marine life? Due diligence conducted showed that there are no environmental regulations or guidelines in Malaysia for the application of EOR chemicals at an offshore platform. For this reason, our team refers to the strictest of regulation for chemicals' use and discharge for an offshore environment used at the North/Norwegian Sea, adopting all qualification criteria from Harmonized Ocean Chemical Notification Format (HOCNF), of the OSPAR Harmonised Mandatory Control System (HMCS), developed through the OSPAR Decision 2000/2. HOCNF ranks chemical products according to Hazard Quotient (HQ), calculated using the Chemical Hazard and Risk Management (CHARM) model. CHARM is a set of rules to determine the risk and extent of surfactant formulation's movement in the ocean - a vital decision making tool to determine if EOR chemicals are safe for use and overboard discharge. This paper describes the ‘environmental-friendliness’ of a newly developed surfactant formulation which will be applied in a Water-Alternating-Gas (WAG) operation at an offshore field in Malaysia using CHARM. First, a comprehensive review of the components of the formulation was conducted, leading to sound selection and/or synthesis of chemistries that confers good environmental properties i.e. non- or low toxicity, persistency, bioaccumulation, with high biodegradability. Next was to determine the degree of toxicity of the formulation at three trophic levels. Using the lowest acute toxicity value, we apply this value to the CHARM model to calculate the dilution of the formulation 500 m radius from the point of discharge - given the expected adsorption, application concentration, and the volume ratio between squeeze vs. produced water. Whether CHARM is exhaustive to decide if the surfactant formulation can be discharged overboard is still being debated. Many argued that it is the responsibility of the chemical manufacturer or product inventor to select or synthesize chemistries with good ecotoxicity properties in the first place. Product innovation has to be aware on new regulation(s) e.g. the banning on the use of a chemical currently used in manufacturing so that the company develops an alternative ahead of its competitors. In the operator's viewpoint, even if the model indicates that the chemical pose a low hazard, physicochemical parameters of the produced fluids has to be monitored beyond the pilot implementation period.
Najamudin, Khairul Ezani (PETRONAS Research Sdn Bhd) | Halim, Nor Hadhirah (PETRONAS Research Sdn Bhd) | Salleh, Intan Khalida (PETRONAS) | Chai Ching Hsia, Ivy (PETRONAS Research Sdn Bhd) | Yusof, M Yusri (PETRONAS Research Sdn Bhd) | Sedaralit, M Faizal (PETRONAS)
This paper examines the requirements, mechanisms and mitigation options for management of produced water from chemical EOR field. As the application of Chemical EOR at Angsi field, the produced water is expected to contain some levels of injected chemicals such as surfactant and polymer.
A key concern is the potential impacts on marine environment in which current field facilities design is not cater for the produced chemicals management. A detail laboratory studies were conducted such as toxicity assessment on local marine fish, grouper indicated the polymer is practically nontoxic with LC50>500 mg/L, and the surfactant is relatively toxic with LC50=1.23 mg/L. The polymer also poses significant environmental concern as it has low biodegradation property with less than 20% are biodegradable in 28 days.
Complicating this situation, alterations of produced fluids physical and chemical properties are also demonstrated. Laboratory analyses of ASP produced fluids predicted higher fluids viscosities, with stable and higher emulsion formed (increment up to 40%) which contributed to higher basic sediments and water (BS&W) percentage. Even minimal scale issues is predicted, mentioned conditions had already contributed significant impact on existing facilities and chemical dosage efficiency and requirements.
The complexities in the conditions render managing ASP breakthrough required defined EOR produced fluid management. In view of current facilities limitations, the study was focused in identifying suitable chemicals and mechanicals mitigation options to treat and manage surfactant and polymer residues toward Angsi Chemical EOR implementation. Recommended solutions were based on laboratory studies, current facilities configuration, technical and regulatory acceptance and economic viability as the actual impacts varied depending on fluids composition and characteristic of the receiving environment.