| Oil exploration and production processes generate a large amount of waste, including drilling fluid, drill cuttings, produced water, etc. If they are not handled properly, contaminants in the waste, like hydrocarbons, heavy meatals, and salts, will enter the environment and cause adverse effects on soil, surface water, underground water and marine environment."End-of-pipe" is no longer competent for dealing with environmental problems in oil E&P industry. Thus, oilfield waste integrated management is a necessary and powful tool to eliminate oilfield waste pollutions.In the first place, oilfield waste management experiences in the United States and Canada were discussed in four aspects, including legislations and regulations, discharge limitations, management technologies, and practices. These management exprerices were compared with oil waste management aspects in our country. It was found that several improvements could be made:promulgating a specific legislation or regulation, refining the discharge standards, introducing best management practices and strengthen the participation of industry associations.In the stage of oilfield waste generation, the source of oilfield waste, characteristics and the methods for volume estimation of drilling fluids, drill cuttings and produced water were analysed and proposed. Oilfield waste were classified into two categories, i.e. hazardous oilfield waste (HOW) and non-hazardous oilfield waste (NHOW). The Chemical Scoring and Ranking Assessment Model (SCRAM) was modified by adding an environemtal effect factor. Subsequently, the modified SCRAM was applied in screening main contaminates in oilfield waste. As a result,54contaminates were identified as main contaminats, including17inorganics,10alkane,8hydrochloric ether,3benzene series,1nitrobenzenes,1phenols,1esters, and14PAH. In the end, potential environmental impacts of the main contaminates in the oilfield waste were elaborated.In the oilfield waste treatment and disposal stage, management technologies of drilling waste and produced water were introduced and compared. They provided basic information for selecting proper oilfied waste management options. The methodologies of life cycle assessment and life cycle cost analysis for oilfield waste treatment and disposal options were developed. Framework of combined LCA and LCC were established. Thereafter, LCA were jointed with LCC under the concept of "Ecological Efficiency". The conbined model called "Life Cycle Perspective Oilfied Waste Management Option Decision Model" was applied in evaluating drill cutting management options in Chenghai Oilfield. Conbined life cycle environmental and economic impact of three Chenghai Oilfield drill cutting management scenarios, which were driven by disel or electricity, was analysed by applying Life Cycle Perspective Oilfied Waste Management Option Decision Model. In addition, the impacts of various weighting methods in life cycle impact assessment (LCIA) on final results were discussed. The results indicated that:power types and LCIA weighting method did not affect the final decision; the best drill cutting management option is Scenario3, i.e. after solid liquid separation pretreatment, drill cutting were loaded and transported to treatment plant to be solidified, and then reused in road paving.In the oilfield waste contaminated land remediation phase, the concept of soil general assessment criteria (GAC) is defined. Parameters of land use scenarios, receptors, buildings, and soil characterizations in CLEA model were replaced by data in China. Physical and chemical properties and toxicity data of28main contaminates in oilfied waste were added in CLEA chemical database as well. GAC of36concerned oilfield waste contaminates in five typical Chinese soil types (i.e. red soil, yellow soil, black soil, purple soil and paddy soil) and three land use scenarios (i.e. residential, agriculture, industry and commercial) were get. Those GACs provided decision makers with a prileminary value to judge whether the site need to be remediated. Technical performance, target contaminants, cost, application conditions, and environmental impact of13oilfield waste contaminated land remediation technologies were discussed. It provided decision makers with basic information for selecting a proper remediation technology. In the end, processse and indicators for screening remediation technologies were developed.Ultimately, an Integrated Oil field Waste Management System (IOWMS) were established. IOWMS were consist of5level one elements and19level two elements,8management aspects, and8operating machanisms. In addition, the effectiveness evaluation index system for IOWMS was porposed. The index system contains4level one indicators,10level two indicators and23level three indicators.5level one elements of IOWMS were policies and objectives, planning, implementation and operation, audit and update, management review.19level two elements of IOWMS included objective and targets, legal requirements, waste identification and classification, facility requirements, waste management plan, risk identification and assessment, risk control practices, orgnisation and responsibilities, training, awareness and capability, system files, files control, operation control, emergency preparedness and response, monitoring, corrective actions, system audit, and documentation. Legal and other requirements, oilfield waste identification, classification and storage, oilfield waste transport and trancking, oilfield waste treatment and disposal, oilfield waste contaminated land risk aseessment and remediation, development of oilfield waste management plan, stakeholders and social responsibility consisted of8aspects of IOWMS. Opration machnisms of IOWMS were comprised of defining policies and targets, organizing accountability agencies, monitoring, developing strict data reporting and examination system, making reasonable oilfiled waste management plan and implementation pordedures, developing file control and documentation system, establish training and conmmunication system, and developing reviewing system. |
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