Dorn, Philip B. (Shell Global Solutions) | Rabke, Stephen P. (M-I SWACO) | Glickman, Andrew H. (ChevronTexaco Energy Research) | Louallen, Jeff (Shell Global Solutions) | Nguyen, Khai (M-I SWACO) | MacGregor, Robert (Halliburton Energy Services Group) | Candler, John E. (M-I SWACO) | Wong, Diana C.L. (Shell Global Solutions) | Hood, Cheryl Ann (Baker Hughes Drilling Fluids) | Hall, John A. (Halliburton Energy Services Group) | Purcell, Thomas W. (American Petroleum Institute)
The offshore oil and gas industry has moved toward the use of synthetic-based drilling fluids (SBF), changing potential exposure scenarios for discharged cuttings when compared to those of water-based drilling fluids (WBF). Unlike WBF, SBF sorbs predominately to particles in the cuttings and are not dispersed extensively into the water column, therefore, a sediment toxicity test was required by the US Environmental Protection Agency (US EPA) in addition to the existing water column test to define a best available technology (BAT) limit. Inclusion of a sediment toxicity test for NPDES compliance was precedent setting and unique. In order to fulfill the US EPA requirements, an inter-industry research group worked with EPA to develop a suitable test that met the technology-based discharge standard.Toxicity of discharged field drilling fluid is compared to a reference SBF (C1618 internal olefin) and, for compliance, the ratio of the reference drilling fluid median lethal concentration (LC) to the field mud LC must be =1.0.Prior to its use, there were concerns that false positive results could cause incorrectly identified non-compliance events, limiting the use of SBF technology. Consequently, initial application allowed the use of a variability (K) factor in determining the ratio. After initiation as a compliance test, research was continued to reduce test variability and minimize false positives. That research included: 1) analysis of NPDES compliance data (500+ tests), 2) two inter-laboratory testing programs, 3) analysis of reference fluid data from one commercial laboratory, and 4) refinements to test sediment type and animal health. The results of these efforts to date are reviewed in this paper and are used to identify potential improvements in the application of the test as a regulatory tool.
The environmental safety of industrial activities in the US has evolved as a self-monitoring system with permittees testing and reporting compliance results to regulatory authorities.For offshore operations in the oil and gas extraction industry, protection of marine resources is of paramount importance. In the US, resources can be protected through the use of water-quality-based and technology-based compliance limits for operations. Water-quality-based limits follow risk assessment principles, where estimated or measured exposures in the environment may be measured against numerical standards such as a chemical indicator (e.g., zinc, cadmium, mercury). Technology-based limits reflect Best Available or Practicable Technology (BAT) for a specific purpose or industrial sector. These limits are derived from the best possible performance of a given technology for controlling possible environmental impacts. In contrast to individual chemical or single parameter measurements, toxicity tests have been increasingly used in both water-quality-based and technology-based compliance in other industries and regulatory jurisdictions to reflect an integration of the "total environment" in assessing the combined potential effects of substances, such as effluents and wastes. Laboratory toxicity tests using an effluent or waste sample essentially integrate the environmental exposures from all potential toxicants or environmental conditions.
However, as with any assessment endpoint for such a test, there is inherent variation with the results, such that "bright line" limitations may result in false positive and negative results, the former leading to violations, and the latter to potential environmental damage. A false positive is an incorrect judgment that the result is not in compliance when it is; a false negative is judging the outcome to be in compliance when in fact it is not. Both present challenges to standardizing testing methods to limit variation due to chance. The introduction or development of such methods therefore requires interaboratory and intralaboratory testing programs to calibrate the variability, a goal that has often been accomplished for water-based drilling fluids and effluents.
Flashing losses from crude oil and condensate storage are routinely vented to the atmosphere.By minimizing operating pressure of low-pressure separators, the amount of flashing losses can be reduced, resulting in increased profits at a minimal cost of implementation and an immediate payback.Companies can be report these methane reductions to the Environmental Protection Agency's Natural Gas STAR Program.Devon Energy realized savings of approximately $7000 per year after separator optimization at one of its oil and gas production facilities.
Drilling waste disposal using hydraulic fracturing is often the preferred waste management option because it can achieve true zero discharge without being limited by the drilling location.This is particularly true for drilling operations in remote and challenging areas such as offshore Sakhalin Island as there is no established infrastructure for drilling waste management.
This paper presents a case history of managing uncertainties and risks related to a drill cuttings re-injection (CRI) project offshore Sakhalin Island. Although there are uncertainties and risks with the CRI project in this case, regulatory requirements and the operator's commitment to zero discharge made it the preferred option for drilling waste management.Complicating the decision was a previous injection well where cuttings settling made it inoperative. Thus, the only option was to inject the oily cuttings into a deviated well intended for future use as a development well, which posed a number of risks related to the proposed CRI operation.
Since this is the only option for drilling waste management and loss of this well would have delayed the drilling program and field development for at least a year, managing the risks and uncertainties related to this CRI project and assurance of a trouble-free CRI operation were critical.
This paper presents monitoring and diagnostic analyses that were used for slurry design and optimization, pumping procedure design and optimization considerations, as well as solids transport modeling and planning length of shut-in intervals between batches.These quality assurance and optimization measures were proven to be effective in managing the risks and uncertainties associated with this critical cuttings injection well off Sakhalin Island.At the time of this writing, more than 100,000 bbl of slurry and fluid had been injected into this well without incident.
Oil and gas exploration and production companies are responsible for managing drilling wastes in a safe and environmentally acceptable fashion that complies with regulation requirements.Tightening environmental legislation worldwide and operators' environmental policies are reducing options for drilling waste management.Subsurface re-injection of drill cuttings and used mud often is the most cost effective, environmentally acceptable method to dispose of these waste products.[1 - 13]This is particularly true for drilling operations in remote and environmentally sensitive areas such as offshore Sakhalin Island where drilling waste treatment and management facilities are usually limited in these isolated areas.
The present paper gives an overview of the environmental impact of cuttings discharges on the bentic sediments, three years after drilling an exploration well (7122/7-1) with formate brine (mixture of potassium and sodium formate) in Production Licence 229 in the southwestern part of the Barents Sea.
Eni conducted a high resolution environmental survey on the physical, chemical and biological conditions of the benthic sediments, in the vicinity of well 7122/7-1 drilled in 2000 in PL229. The cuttings and mud from the well were released to the environment as the drilling operation was conducted before the political decision to restrict the discharge of cuttings and mud from operations using water based mud (WBM) in the Barents Sea¹.
The aim of the study was to verify findings in a life cycle assessment (LCA ) that had been conducted for formate brine, which concluded with:
"The findings of the study indicate that the discharge of moderate amounts of Formate Brines is not likely to lead to potentially significant negative impacts on the marine environment." ²
Samples were collected from 27 stations surrounding well 7122/7-1. Apart from the reference station, all stations were within 500 meters of the well head (reference station about 3 km to the south of the well head). Samples from 22 stations were analysed physically/chemically and 19 stations were analysed biologically, in addition to the reference station. As stations were very close to each other, very high sampling accuracy was of crucial importance.
The findings in this study are in line with the conclusion in the LCA as only minor environmental impact in the vicinity of the drilling location was detected.
Decommissioning of offshore oil and gas production facilities in California has always been and will continue to be a controversial and hotly debated topic.This Decommissioning has been occurring since the early part of the 20th Century and most recently involved four offshore platforms, a pier, and an island in State waters.It also involved the abandonment of over 23 sub sea wells and associated debris off the Santa Barbara, California Coast.Much was learned from these many decommissioning projects, and organizations were formed to coordinate future decommissioning projects and discuss alternatives. This presentation will summarize the lessons learned from past decommissioning projects, future projects and options available for future projects.There will be a discussion on the positions of the public, environmental communities and government on the approval process, facility removal process and final disposition of the facility.Focus of the presentation will be on the process that could be used to develop viable decommissioning options.
This paper was part of a student paper session at the conference.This paper was included in the proceedings as STUDENT5.
Well cement problems such as small cracks or channels can result in gas migration and lead to sustained pressure at casingheads (SCP). Regulations require removal of significant SCP while tolerating small SCP during production operations. However, SCP of any size must be removed prior to well plugging and abandonment (P&A) as it is believed that even very small leaks might lead to continuous emissions of gas to the atmosphere. In some wells, however, small gas leaks may diminish in time as the gas migration channels are plugged off by the gas condensate. Thus, the objective of this work was to develop a method for computing potential of self-plugging in wells with SCP using priciples of phase behavior and theory of two-phase flow in small channels.
In the industrialized world, today, particularly over cities, air pollution is being contonously generated by smoke from automobiles, factories and hundreds of other sources. There are noxious gases like carbon monoxide, sulfur dioxide and oxides of nitrogen. Air pollution does millions of dollars worth of damage to human being and agricultural crops. The United States, with the world's largest economy, is also the world's largest single source of anthropogenic (human-caused) greenhouse gas emissions. Quantitatively, the most important anthropogenic greenhouse gas emission is carbon dioxide, which is released into the atmosphere when fossil fuels (i.e., oil, coal, natural gas) are burned. In addition to carbon dioxide, oilfiled production facilities are a source of natural gas emissions from gas dehydration units, leaking valves, gaslines and oil storage tanks.[1, 2, 3] Also, natural gas leaks may occur from tubing or casing string often due to poor thread connection, corrosion, or thermal-stress cracking
The Clean Air Act of 1970 categorized emission sources into two types: mobile source such as automobile, ships, airplanes and stationary emission source which includes refineries, well facilities, oil and gas tanks, etc. Also, with the direction of the act, EPA established National Ambient Air Quality Standards and calculation methods based on air concentration and emission rates to assess the risk of air pollution.[5, 6 7] For the oilfield production facilities, emission rates are computed using published values of emission factors - multipliers specific for the equipment installed in the facility.  There are no emission factors, however, for leaking petroleum wells.
Considerable number of producing and abandoned wells with SCP constitute a potential new source of continuous natural gas emission from failed casingheads due to poor cementing and external gas migration. The gas migration in cement can be diagnosed with the SCP testing procedures involving casing pressure bleed-off followed with pressure buildup. The tests provide data for assessing gas emission rates - the first component of risk analysis. (The theory ofSCP testing, - developed at LSU - provides estimation of cement leak conductivity and gas source pressure - a two data needed for computing the emission rate.) Another component is the continuity of gas emission, as some wells may cease to emit gas in time due to source depletion or self-plugging with condensate.
In condensation, natural gas fractions turn into liquid when pressure and temperature drop below the dew point. The condition of gas condensation could be induced downhole in the cement channel by rapid pressure drop at the surface resulting from failure of containment (casinghead). If the channel is small, condensate liquid will block the gas flow and terminate gas migration.
As the gas emissioin from wells may lead to different outcomes. there is a need to develop a method for predicting potential air pollution from the SCP wells. The method should provide prediction of emission rate and - more importantly - the well's potential for self-plugging, estimation of the flowing time and total gas volume emitted to the atmosphere.The method should be theoretically derived by coupling the PVT gas behavior with critical conditions for liquid blockage in the cement's flow channels.
The paper describes the development, implementation and application of a program of environmental performance measurement in a global service company working the in exploration & production industry.
A set of environmental performance indicators has been defined in order to provide data on internal compliance, environmental incidents, resource consumption, and waste generation (and management). Information is captured in an on-line database from over 500 sites in approximately 100 countries, on a monthly basis, and is immediately available for analysis and management review. The paper discusses the selection of the indicators that are used, and the intended value of each indicator, or group of indicators.
Having described the basis for the EPI program, examples from the data capture and management review process are presented. These examples are used to illustrate the evolution of the EPI process over the past three years. There is particular emphasis on discussion of the challenges that are presented by a highly devolved and decentralized data capture process.
The third section of the paper concerns the trends and themes that are evident from the database, and their application and value to the management process. There is a discussion of indicators that have been removed from, or added to the program and the reasons for those changes.
The paper concludes with a discussion of the possible areas for future development of the program.
An integral component of an Environmental Impact Assessment is the Socio-economic Assessment. The purpose of these assessments is to identify and evaluate potential impacts of proposed projects on the socio-economic environment of fenceline communities that would most likely be directly impacted by the project.
With the enactment of the Certificate of Environmental Clearance (CEC) Rules in Trinidad in 2001, Exploration and Production (E&P) companies must now apply to the Environmental Management Authority for an environmental permit for any activity designated under these rules. As a result, oil and gas operators in Trinidad have collected a significant amount of socioeconomic data as part of Environmental Impact Assessments (EIA?s) and Environmental Baseline Surveys for CEC applications.
The state owned oil company, Petrotrin, set the standard for conducting socio-economic assessments for energy development projects in Trinidad and did so on a voluntary basis before the CEC Rules were enacted using guidelines developed by the Regional Association of Oil and Natural Gas Companies in Latin America and the Caribbean (ARPEL).
In conducting socio-economic assessments, surveys were conducted for households, community leaders, business proprietors and focus groups. Generally 25% of the population are interviewed in the process to determine their views and aspirations on potential impacts of oil and gas E&P projects based on their historical experience. If effectively conducted, socio-economic assessments are a valuable tool for determining community needs and ensuring win- win partnerships between oil and gas companies and the communities in which they operate.
This paper describes the process by which Petrotrin has conducted socio-economic assessments for EIA's and Environmental Baseline Surveys for fenceline communities where E&P development activities are planned. It also seeks to give an historical overview of how E&P operations have impacted fence line communities in southern Trinidad over the 20th century.
Neff, Jerry M. (Battelle Memorial Institute) | Hart, Alan D. (Continental Shelf Associates) | Ray, James (Oceanic Environmental Solutions) | Limia, Jose (Baker Hughes Drilling Fluids) | Purcell, Thomas (American Petroleum Institute)
The Gulf of Mexico Comprehensive Synthetic Based Muds Monitoring Program used a combination of physical, chemical, and biological measurements to survey fourteen drill sites on the continental shelf and continental slope of the Gulf of Mexico where cuttings generated during drilling with synthetic based drilling muds (SBM) had been discharged.The three continental shelf and three continental slope sites selected for more intensive investigation are the focus of this paper. The objective of the program was to document the distribution of cuttings in drill site sediments and to characterize the areal and temporal extent of chemical and biological changes due to cuttings discharges.None of the drill sites had large cuttings piles such as have been observed in the North Sea.Chemical and physical measurements in sediments collected during two surveys one year apart at a subset of eight of the drill sites showed that deposition of discharged SBM cuttings solids was limited to a radius of less than about 250 m from the discharge location. Mean synthetic based fluid chemical (SBF) concentrations in near-field sediments decreased during the year between sampling surveys.Benthic ecology parameters were measured at the three continental shelf discharge sites and sediment toxicity to amphipods was measured at the three continental shelf and three continental slope discharge sites.The benthic community within 250 m of the site with the highest SBF concentrations in sediments had reduced benthic faunal abundance and diversity. Benthic communities were only slightly disturbed at the other two sites. Amphipod survival exceeded 75% in sediments collected within 250 m of most of the drill sites on the continental shelf and slope, indicating that most SBM cuttings-contaminated sediments, even those close to the drill sites, were not toxic.A sediment quality triad (SQT) analysis, used to characterize the impacts of drilling discharges on sediment quality at the three continental shelf sites, identified a gradient of decreasing disturbance with distance in sediments collected within 250 m of the drill sites compared to sediments > 3000 m away. There was strong evidence that chemical and ecological recovery of sediments near SBM cuttings discharges was progressing during the year between the sampling surveys.