ENVIRONMENTAL STATEMENT BARDOLINO DEVELOPMENT

More documents

Recommendations

Info

Bardolino Development Environmental Statement 3.4.7 Cementing Chemicals Cement is used to secure the steel casing in the well bore, and the cementing chemicals are used to modify the technical properties of the cement slurry. During cementing operations, the majority of these chemicals are left downhole but a small quantity of cement may be discharged onto the seabed around the top of the casing. However, the chemicals used will be contained within inert cement and will therefore not pose a threat to the marine environment. Careful estimates of the final volume of the hole will be made during drilling, and the volume of cement used will be adjusted accordingly to minimise the risk of excess cement being squeezed out of the hole onto the seabed. A number of chemicals will need to be added to the cement. The exact chemical constituents required to formulate the cement will be confirmed during the final stages of well design. They will be included in the detailed chemical risk assessment of the PON 15B which will be submitted to BERR at least 28 days prior to commencement of drilling activities as required by the Offshore Chemical Regulations 2002. 3.4.8 Contingency Chemicals Contingency chemicals will be held on the rig for use in unplanned events. Potential applications would be to free a stuck drill string, or seal highly porous or fractured zones to prevent the uncontrolled loss of drilling fluid. A detailed risk assessment for contingency chemical use will be submitted to BERR as required by the Offshore Chemical Regulations 2002. 3.4.9 Handling Mud and Cuttings Once on board the rig, drill cuttings are removed from the drilling mud by solids control equipment. Where LTOBM is used the mud and cuttings will be treated by the solids control equipment before being intercepted by a collection device. The cuttings will be transferred from the solids control equipment and then either dried and collected in skips ready for transfer to a supply vessel, or slurrified and pumped directly to the bulk tanks of a supply vessel for transport to shore. Once onshore the cuttings are processed until they have very low oil content and then disposed of. The base oil residue recovered during this process is returned to the mud company. Shell’s “Ship to Shore Cuttings Disposal Guidelines” will be followed during the planned LTOBM phase. In the event of unexpected hole conditions (e.g. faster than expected penetration rates), equipment breakdown or failure, or operational and logistics downtime due to adverse weather conditions, contingency arrangements will be in place to permit storage of cuttings on board the rig until normal operations are resumed. If necessary, unless personnel safety or installation integrity is threatened, drilling will cease in preference to the discharge of LTOBM-coated cuttings to sea. However, in the event of a major safety incident where no compromise on safety risks to personnel or asset can be made, the contingency will exist to divert limited quantities of cuttings overboard. 3.4.10 Well Clean-up and Testing Operations Once drilling has been completed, the Bardolino well will be circulated clean prior to completion, and then tested. The exact chemicals required for these processes will be included in the chemical risk assessment of the PON 15B as required by the Offshore Chemical Regulations 2002. Hydrocarbons produced during the well flow clean-up and testing will be flared. The aim of well clean-up is to remove detritus from the well prior to running the completion. It also removes solids that could impair both mechanical operations in the well bore and reservoir performance once the well has been perforated. The potential emissions from well clean-up and testing of the development well have been calculated based on a total testing and clean-up period of 48 hours with a maximum of 15,000 bbls of oil, with an expected GOR of 870 scf/bbl ( Table 3.4). This represents a worst case for emissions. There is no intention to perform an extended well test, and it is likely that the quantity of oil flared during well clean-up and testing April 2008 Page 3-11
Bardolino Development Environmental Statement operations will be less than approximately 8,000 bbls. The impact of emissions from the proposed well clean-up and testing is assessed in Section 6.3. Table 3.4: Summary of emissions (in tonnes) from flaring of gas and oil during well clean-up and testing for the Bardolino Development well Emissions CO2 CO NOx N20 SO2 CH4 VOC Oil (tonnes) 6,413.50 36.08 7.42 0.16 0.03 50.11 50.11 Gas (tonnes) 941.06 2.25 0.40 0.03 0.004 15.12 1.68 Total 7,354.57 38.33 7.82 0.19 0.03 65.23 51.79 Note: Conversion factors based on UKOOA well testing emission factors, assuming 95% flare efficiency: Oil 3.2 0.018 0.0037 0.000081 0.0000128 0.025 0.025 Gas 2.8 0.0067 0.0012 0.000081 0.0000127 0.045 0.005 Source: 2002 EEMS Guidelines for the Compilation of an Atmospheric Emissions Inventory Revision 4 3.4.11 Drilling Rig Utilities The utility operations of drilling vessels include such activities as facility maintenance, management of drainage, accommodation services and deck operations. 3.4.12 Noise Emissions Resulting from Proposed Operations In general terms, sound can be characterised with reference to two features, the frequency at which it is emitted (measured in hertz (Hz)) and its strength or intensity. Noise from various sources may combine or cancel to produce a pattern of noise in the marine environment that is characterised by variations in frequency and noise level. Noise levels in the marine environment are attenuated by distance (dispersion in 3 dimensions), and by absorption by the water. The degree of absorption is roughly in proportion to the square of the frequency (Richardson et al., 1995). The dominant sound sources from the project result from: • a semi-submersible drilling rig; • a standby vessel; • 3 anchor handling tug vessels (AHTVs) • a guard vessel • a DP pipelay vessel (which utilises thrusters to maintain its position); • a trenching vessel • a survey / umbilical vessel; • a dive support vessel (DSV) to tie-in and commission pipeline; • a rock dump vessel; and, • piling the subsea structures (Section 3.6.2). Approximate noise levels can be calculated at given distances using formulae presented in Richardson et al. (1995), and a formula for absorption given by Erbe and Farmer (2000). Since the water depth in the development area is approximately 90 m, a model of cylindrical spreading has been used rather than spherical spreading. In relatively shallow water, cylindrical spreading results in a larger zone of influence than for spherical spreading in deep water. The formula used is: Lr = Ls – 15 log H – 5 log R – 60 (dB) Received Level (Lr) = Source Level (Ls) – correction for depth (H, km) – distance (R, km) attenuation – Correction between m and km Page 3-12 April 2008
Page 1 and 2: ENVIRONMENTAL STATEMENT BARDOLINO D
Page 3 and 4: Bardolino Development Environmental
Page 39: Bardolino Development Environmental
Page 91 and 92:
Bardolino Development Environmental
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
13 th March 2008 Dear Sir or Madam,
Page 183 and 184:
To: Paul Wood Shell U.K Limited, Se
Page 193 and 194:
Page 195 and 196:
What risks to marine mammals do pil
Page 197 and 198:
Noise propagation modelling. Noise
Page 199 and 200:
If, for any reason, piling operatio
Page 201 and 202:
APPPENDIX 1 MARINE MAMMAL RECORDING
show all

ENVIRONMENTAL STATEMENT BARDOLINO DEVELOPMENT

Create successful ePaper yourself

Delete template?

Save as template?