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1、Environmental Implication of Exploration of Hydrocarbons&Mitigation Measures,NELP Blocks in India,Rajasthan(RJ),Gujarat-Kutch(GK),Gujarat-Saurashtra(GS),Mumbai(MB),Kerala-Konkan(KK),Cavery Basin(CY),Krishna Godavari(KG),Mahanadi(MN),West Bengal(WB),Tripura(ON),Assam-Arakan(ON),CB-ON,MN-ON,CY-ON,I N
2、D I A,Offshore Blocks,Krishna-Godavari,East Coast,Cauvery Basin,Mahanadi,West Bengal,Andaman,Mumbai,West Coast,Kerala-Kokan,Gujarat-Saurashtra,Gulf of Kutch,Onshore Blocks,Cambay Basin,Assam-Arakan,Mahanadi,Chennai,Disposal of Drill Cuttings&Drilling Fluids,OnshoreDrill cuttings originating from on-
3、shore or locations close to shore line and separated from Water Base Mud(WBM)should be properly washed and unusable drilling fluids such as WBM,Oil Base Mud(OBM),Synthetic Base Mud(SBM)should be disposed off-site or on-site.The disposal pit should be provided with leachate collection system.Details
4、of design in respect of the impervious waste disposal pit and capping of disposal pit should be provided by the oil industry to concerned SPCB at the time of obtaining consent.,Regulations,Onshore(contd)Use of diesel base mud is prohibited.Only WBM should be used for on-shore oil drilling operations
5、In case of any problem arising due to geological formation for drilling,low toxicity OBM having aromatic content 1%should be used.If the operators intend to use such OBM to mitigate specific hole problem,it should be intimated to MoEF and SPCBThe chemical additives used for the preparation of drilli
6、ng fluids should have low toxicity i.e.96 hr LC50.30,000 mg/l as per mysid toxicity or toxicity test conducted on locally available sensitive sea species.The chemicals used(mainly organic constituents)should be biodegradable,Disposal of Drill Cuttings&Drilling Fluids,Regulations,Onshore(contd)Drill
7、cuttings separated from OBM after washing should have oil content 10 gm/kg for disposal into disposal pit.The waste pit,after it is filled up,shall be covered with impervious liner,over which,a thick layer of native soil with proper top slope be provided.Low toxicity OBM should be made available at
8、installation during drilling operation.Drilling wastewater including drill cuttings wash water should be collected in a disposal pit,evaporated or treated and should comply with the notified standards for on-shore disposal.,Disposal of Drill Cuttings&Drilling Fluids,Regulations,Onshore(contd)Barite
9、used in preparation of drill fluid shall not contain Hg 1 mg/kg&Cd 3 mg/kgTotal area acquired for preparation of drill site must be restored after completion of drilling operation leaving no waste material at site.SPCB should be informed about the restoration work.In case,environmentally acceptable
10、methods for disposal of drill waste such as(i)Injection to formation through casing annulus,if conditions allow,(b)land farming at suitable location(c)bio-remediation,(d)incineration or(e)solidification,are considered for adoption by oil industry,then proposal shall be submitted to SPCB and MoEF for
11、 approval.,Disposal of Drill Cuttings&Drilling Fluids,Regulations,OffshoreUse of diesel base mud(OBM)is prohibited.Only water base mud(WBM)is permitted for offshore drilling.If the operators intend to use low toxicity OBM or SBM to mitigate specific-hole problems in the formation,it should be intima
12、ted to MoEF and SPCB.The low toxicity OBM should have aromatic content 30,000 mg/l as per mysid toxicity of test conducted on locally available sensitive sea species.,Disposal of Drill Cuttings&Drilling Fluids,Regulations,Offshore(contd)Hexavalent chromium compound should not be used in drilling flu
13、ids.Alternate chemicals in place of chrome lignosulfonate should be used in drilling fluids.In case,chrome compound is used,the drilling fluids and drill cuttings should not be disposed offshore.Bulk discharge of drilling fluids in offshore is prohibited except in emergency situations.WBM/OBM/SBM sh
14、ould be recycled to a maximum extent.Unusable portion of OBM should not be discharged into Sea and shall be brought to on-shore for treatment&disposal in an impervious waste disposal pit.,Disposal of Drill Cuttings&Drilling Fluids,Regulations,Offshore(contd)Thoroughly washed drill cuttings separated
15、 from WBM/SBM&unusable portion of WBM/SBM having toxicity of 96 hr LC50 30,000 mg/l,shall be discharged off-shore into Sea intermittently at an average rate of 50 bbl/hr/well from a platform so as to have proper dilution and dispersion without any adverse impact on marine environment.Drill cuttings
16、of any composition should not be discharged in sensitive areas notified by MoEF.In case of specific hole problem,use of OBM will be restricted with zero discharge of drill cuttings.Zero discharge would include re-injection of the drill cuttings into a suitable formation or to bring to shore for prop
17、er disposal.In such case,use of OBM for reinjection should be recorded and such records made available to the regulatory agency.Low toxic OBM having aromatic content 1%should be made available at the installation.,Disposal of Drill Cuttings&Drilling Fluids,Regulations,Offshore(contd)In case,drill cu
18、ttings are associated with high oil content from hydrocarbon bearing formation,then disposal of drill cuttings should not have oil content.10 gm/kg.The drill cuttings wash water should be treated to conform with the limits notified under EPA,before disposal into sea.The treated effluent should be mo
19、nitored regularly.Discharge of drill cuttings from the installatilon located within 5 km away from shore should ensure that there is no adverse impact on marine eco-system and on the shore.If,adverse impact is observed,then the industry has to bring the drill cuttings on-shore for disposal in an imp
20、ervious waste disposal pit.,Disposal of Drill Cuttings&Drilling Fluids,Regulations,Offshore(contd)If any,environmental friendly technology emerges for substitution of drilling fluids and disposal technology it may be brought to the notice of MoEF and regulatory agencies.If the operator desires to ad
21、opt such environment friendly technology,a prior approval from MoEF is required.Barite used in preparation of drilling fluids shall not contain Hg 1 mg/kg&Cd 3 mg/kg.Oil drilling operators are required to record daily discharge of drill cuttings&drilling fluids to offshore and also to monitor daily
22、the effluent quality,and submit the compliance report once in every six months to MoEF.Enforcing Authority and the frequency for monitoring of ambient air&marine water quality in respect of offshore installations,as discussed,may be decided by the MoEF before notification of these guidelines.,Dispos
23、al of Drill Cuttings&Drilling Fluids,Regulations,Regulations,Wastewater Discharge BOD5=40-50 mg/l or lessCOD=90-120 mg/l or lessSuspended solid=30-40 mg/l or lessColiform count=200/100 ml,Scope of Work for EIRA Studies for Offshore Projects,Collection of baseline environmental quality data for asses
24、sment of quality of marine environment including water,sediment and biological components Assessment of hydrography data in the study regionIdentification,predication and evaluation of significant impacts due to proposed exploratory drilling,Scope of Work for Offshore Project(Contd),Evaluation of pr
25、oposed pollution control facilities at the rig and recommendation of appropriate measures for pollution control Preparation of environmental impact statementDelineation of Environmental Management Plan(EMP)for mitigation of adverse impacts due to the proposed exploratory drilling Delineation of post
26、 project environmental quality programme,Details of Work Plan for Offshore Project,Baseline Status,Assessment of abiotic environment for water and sedimentAssessment of biotic environment for water and sedimentAssessment of primary and secondary productivity in the region Collation of hydrography da
27、ta viz.current speed,direction,temperature gradient for assessing dilution and dispersion of wastes discharged from the rig in offshore areasAssessment of quality and quantity of wastes to be discharged in sea from drilling rigsCollection of data on coastal morphology and topography adjacent to the
28、block,Environmental Impact Studies for Offshore Project,Identification,quantification and evaluation of impacts on marine environment due to proposed exploratory drilling through:Mathematical models describing transport/dispersion,fate and effect of routine wastewater discharges and routine oil/chem
29、ical loadings from floater/rigAssessment of impact on marine productivity and diversityAssessment of positive and negative impacts on human interests with respect to fishing activity due to proposed exploratory drillingAssessment of impacts on coastal environment including ecologically sensitive are
30、as,water bodies,intertidal and CRZ areas due to proposed drilling,Details of Work Plan for Onshore Project,Baseline Environmental Quality Status,Assessment of abiotic environment for water and soil components in terms of pH,buffering capacity,nutrient load,heavy metals,hydrocarbons and oil/grease et
31、c.Assessment of biotic environment for water and soil components in terms of phytoplankton/zooplankton(enumeration,indices and distribution)Assessment of primary and secondary productivity in the regionAssessment of quality and characteristics of wastes to be generated from drilling operationsIdenti
32、fication of eco-sensitive and protected areas such as forests etc.,Collation and collection of environmental quality data/information for assessment of existing status/quality of air,noise,water,land,biological and socio-economic components of environment in and around the region proposed for drilli
33、ng operationsIdentification,prediction and evaluation of significant environmental impacts due to proposed drilling operationsPreparation of environmental impact assessment statementDelineation of environmental management plan for mitigation of adverse impacts,Objectives of Study for Onshore Project
34、,The study report is aimed at obtaining approvals from the regulatory agencies viz.Assam State Pollution Control Board,Assam State Environment and Forest Department.If the project cost exceed Rs.100 crores,approval from the Ministry of Environment and Forests(MoEF),New Delhi will also be required.Th
35、e studies shall cover the following:,Assessment of air quality around proposed drilling locationAssessment of noise levels in the vicinity of drilling locationAssessment of water quality in terms of its physico-chemical and biological characteristics in the vicinity of proposed drilling locationsAss
36、essment of soil quality in terms of texture porosity heavy metal and biological diversity at the drilling location and in its vicinity Assessment of terrestrial ecology and diversity of flora in the block and near the drilling location Assessment of quantity and characteristics of wastes to be dispo
37、sed during drilling operationsIdentification of eco-sensitive and protected areas such as Reserved forests,Bird sanctuaries etc.,Work Plan for Onshore Project,Baseline Environmental Quality Status The data will be collated for the block area.Primary data around the proposed drilling location will be
38、 collected for all the components.,Identification,quantification and evaluation of impacts on air,water and land environment including terrestrial ecology and parameters of human interest due to proposed drilling operations,Environmental Impact Assessment for Onshore Project,Environmental Management
39、 Plan for Onshore Project,Suggestion of appropriate measures to prevent/minimise potential impacts due to the drilling activity on various components of environment Preparation of environmental quality monitoring programme during drilling operations,Risk Assessment,Identification of vulnerable opera
40、tionsEstimation of hazard distances with recourse to maximum credible accident scenariosProposed risk mitigation measures Delineation of Disaster Management Plan,Objectives,Scenarios Assumed for Consequence Analysis,Jet fire due to accidental release of natural gas Jet fire due to accidental release
41、 of oil and gas mixturePool fire of crude oil spilled on sea surface,Wastes Envisaged in Exploratory Drilling,Drill Cuttings m3/well:91 500 Wastewater during drilling operation m3/d:25 30 Sewage m3/d:30 35,Physico-chemical Characteristics of Combined Wastewater from Drilling Operations,Three Dimensi
42、onal Plume of Suspended Solids,Concentration Vs Central Line Distance,Prediction of Impact Due to Discharge of Drilling Fluids and Drill Cuttings,In this study CORMIX 1 was used to predict the impact due to discharges of drill wastes discharge from drilling operation;discharge depth 20 m It is infer
43、red from the model that the effect of the wastewater being discharged is localized,persists up to distance of 100 meter from the discharge port,and the background concentration is nearly attained Considering the wastewater quantity as 60 m3/d(30 m3/d shale shaker,desander,desilter+30 m3/d domestic w
44、astewater)with 40 mg/l BOD,the total load per day would be 2.4 kg.With the dilution of 105 times,the ultimate BOD load in the discharge point at a depth of 10 m would be less than 1 mg/l.Hence,impacts on characteristics of water column and benthos due to drilling activity in the study region will be
45、 negligible.The water based drilling mud is non toxic to the marine organismsDrilling mud toxicity,LC50 is 30,000 mg/l hence impact on biological component in water column is not envisagedDrill cutting(average 150 m3/well or 3-5 m3/d)would be discharged below the water surface through a pipe and wou
46、ld distribute evenly on sea bed(depth 27 170 m).Benthic fauna at the drilling location may temporarily be affected but would recover to normal after drilling is completed.,Prediction of Impacts due to DG Sets,NOx emission from all the DG sets together has been computed to be around 1.0 g/sec.Conside
47、ring the height of release(about 15 m above sea surface including the height of stack of DG set i.e.5-6 m and the platform),wind directions both in SW and NE,and wind speeds varying from 11-25 km/hr.,the maximum concentration of NOx at sea surface will be around 5 g/m3 at a distance of about 2 to 3
48、km in downwind direction.The location of drilling is 10 km away from coast hence the impact on land and coastal areas is not envisaged.The air quality monitored in offshore area in earlier studies also shows ambient levels of NOx to be around 5-6 g/m3,Environmental Impact Statement,The modeling stud
49、ies indicate that the rise in turbidity levels is restricted to 100 m zone from rig and recover immediately due to dilution available at 20 m depth.The discharge of drill cuttings at this depth will temporarily affect benthic community for shorter duration and recover to normal after the activity is
50、 completed.The sediment near the rig will be disturbed due to drill cuttings discharge during drilling operation.Though the duration of drilling is 22-47 days,actual drilling time is only 40%of the duration and wastes are generated only during drilling.,Marine Environment,Low toxicity WBM,having 96
