Executive Summary
Offshore drilling for oil and natural gas have been ongoing since the 1800’s but little emphasis has been placed on the fate of drilling waste acquired during the drilling process. There are three main categories of waste that represent a potential concern based on current disposal practices. These waste categories are drilling fluids, drill cuttings and produced formation water (PFW). Existing and proposed policies related to the handling and disposal of these wastes will be reviewed here.
Drilling fluids, drill cuttings and PFW are presently regulated in the US by the National Pollutant Discharge Elimination System (NPDES). Drilling fluids can be grouped into 3 main types which are Water Based Muds (WBM), Oil Based Muds (OBM) and Synthetic Based Muds (SBM). These muds are regulated differently in all countries overseeing offshore drilling activities. The US currently has regulations governing the discharge of drilling fluids and they state that there should be no discharge of oil-based fluids, a toxicity measurement stating that 96hr LC- 50 must not be exceeded at a suspended particle phase concentration of 30,000ppm and barite which is a weighting agent present in drilling fluid must not contain more than 1mg/kg mercury and 3mg/kg cadmium. These requirements are not sufficient to mitigate environmental concerns therefore alternatives to current US policy will be examined.
Drill cuttings are solids obtained during the drilling process and their discharge is also regulated in the US and abroad. A review of the management of these cuttings and the adverse effect of their exposure on the marine environment is examined. Stringent regulations have been recommended in order to reduce the discharge of drill cuttings to the sea.
PFW is one of the largest wastes, by volume, generated during offshore drilling. The US NPDES regulations include a limit for the daily and monthly average oil and grease concentrations of PFW but such limit is not sufficient for regulating PFW. Norway has a feasible and adequate policy for regulating PFW and the US should consider implementing additional regulation inline with some of these policies for PFW.
To further reduce environmental impact caused by drilling waste, the US should consider regulations such as detailed laboratory analysis from independent laboratories, conduction of static sheen test 5 times a month, proper documentation for toxic chemicals and their concentrations present in drilling wastes and recycling of drilling waste when feasible. These regulations were adopted from the Norwegian discharge permit regulations.
Table of Content
1. Introduction
1.1. History of Offshore drilling………………………………………………………..5-6
1.2. The Drilling Process and Technology used in Offshore drilling…………………..6-9
1.3. Geotechnical Designs used in oil and gas drilling………………………………….9-10
1.4. Phases in oil and gas production…………………………………………………..10-11
1.5. Waste generated during drilling…………………………………………………….11
1.5.1. Drilling fluid………………………………………………………………..11-14
1.5.2. Dill cuttings………………………………………………………………...14-15
1.5.3. Produced Formation Water (PFW)…………………………………………15
1.5.4. Oil leaks and Spills…………………………………………………………15-16
1.5.5. Green house gases (GHG) Emissions………………………………………17
1.5.6. Fugitive Emissions………………………………………………………….17
1.6. Drilling Waste Management……………………………………………………….18
1.6.1. Drilling mud an d cuttings………………………………………………….18-19
1.6.2. Produced formation water………………………………………………….19-20
2. Challenges
2.1. Environmental Challenges associated with waste disposal during offshore drilling..20-21
2.1.1. Drilling fluid…………………………………………………………………21-22
2.1.2. Drill Cuttings………………………………………………………………...23
2.1.3. Produced formation water…………………………………………………...23-24
2.2. Cost and Benefits Analysis of offshore drilling……………………………………..25-29
3. Comparative Analysis
3.1. Oslo –Paris Convention for the Protection and Treatment for Marine Environment of the North-Ease Atlantic (OSPAR)…………………………….........................................30-32
3.2. Comparisons of Drilling waste regulations in USA with other countries…………...32
3.2.1 Drilling fluids and cuttings……………………………………………………32-34
3.2.2. Produced formation water……………………………………………………34-35
4. Recommendations………………………………………………………………………..35-38
Figure 1- Gas Production in offshore fields, Lower 48 States………………………………6
Figure 2- A jack-up rig………………………………………………………………………7
Figure 3- A drilling barge……………………………………………………………………7
Figure 4- A semisubmersible rig…………………………………………………………….8
Figure 5- A drillship in the Beaufort Sea…………………………………………………….8
Figure 6- Offshore drilling platforms………………………………………………………..8
Figure 7- A Shale Shaker removing cuttings………………………………………………..18
Figure 8- Vertical Cutting Dryer…………………………………………………………….19
Figure 9- Dried cuttings……………………………………………………………………...19
Figure 10- Proved Reserves by Area, 2009…………………………………………………..27
Table 1- List showing major component of drilling fluids and their maximum concentration…21
Table 2- A comparison between consumption of gasoline and other petroleum product……….25
Table 3- U.S offshore crude oil production 2004-2009…………………………………….25
Table 4- U.S Natural gas supply, 2004-2009……………………………………………….26
References…………………………………………………………………………………. 38-42
