Environment Report 2014

ENVIRONMENT REPORT 2014

5. Well Flow Survey 5.1 Introduction

Since the Macondo oil release in the Gulf of Mexico in 2010, the UK offshore oil and gas industry, in collaboration with regulators, has extensively reviewed the industry’s prevention and response capability. An element of this review is to understand whether a significant accidental oil release could occur from a well blowout on the UKCS by developing an inventory of well flow status. Any well that does not naturally flow oil or gas to the surface (that is, if it requires assistance to flow) does not have the potential to release oil or gas into the marine environment and is therefore described as a ‘no flow’ well. In 2013, Oil & Gas UK conducted a survey of operators’ platform wells to establish their unassisted flow potential. From this survey, the well flow status of all platform wells on the UKCS was recorded, the results of which are presented in Oil & Gas UK’s Environment Report 2013 23 . The total platform well inventory consists of 5,121 wells, 21 of which can flow at a rate greater than 5,000 barrels of oil per day (bopd). In 2014, Oil &Gas UK carried out a complementary survey to develop a well flow status inventory of subsea wells on the UKCS. At the time of writing, this work is still under way with almost 80 per cent of all subsea well data received from operators. When the survey and analysis are complete, an addendum to this report will be published. The interim results illustrate that few subsea wells are capable of unassisted flow. Of the 5,754 subsea wells in the inventory so far, just 90 are capable of flow at rates that could result in a significant accidental oil release. The overall results presented in this chapter are unlikely to change dramatically because almost half of the remaining wells to be surveyed are plugged and abandoned and are therefore expected to be classified in the ‘no flow’ category. The majority of the outstanding wells in the survey are also expected to be gas wells; in the event of a blowout, gas readily disperses into the water column. This chapter highlights the methodology used to conduct the subsea well flow survey, following a similar procedure to last year’s platform well survey. The preliminary results have been combined with the platform wells data to illustrate initial results of the total well inventory. For subsea wells with unassisted flow potential, an overview of the well type and flow rate class is outlined. 5.2 Survey Design In 2014, all operators with subsea wells were sent a pre-populated spreadsheet containing individual well information from the UKOil&GasData (previously DEAL) Database 24 . The following information was requested: • Is the well capable of unassisted flow? • Well type – is it an oil, gas or condensate well? • Gas oil ratio (GOR) • Specific gravity • Well pressure class banded into five categories • Flow rate class (oil) banded into six categories • Flow rate class (gas) banded into six categories

23 Oil & Gas UK’s Environment Report 2013 is available to download at www.oilandgasuk.co.uk/publications/viewpub.cfm?frmPubID=772

24 UKOilandGasData is an online resource of information that supports oil and gas business activities. UKOilandGasData is a register of metadata (including spatial information) about UKCS wells, seismic surveys, licences and infrastructure. For more information, please visit www.cdal.com/our-services/ukoilandgasdata.cfm

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