BHP BILLITON PETROLEUM LIMITED Liverpool Bay Relinquishment Report for Licence P1551 (110/15b)
P1551 110/15b Licence Relinquishment Report 1 Header Licence Number: P1551 Licence Round: 24 th Round, Awarded June 2007 License Type: Promote Block: 110/15b License Administrator: BHP Billiton Petroleum Great Britain Ltd Work Programme Summary: Obtain 500km of 2D seismic data; and reprocess 100km of 2D seismic data 2 Synopsis Prior to the 24th bid round BHP Billiton had identified several notional leads in the 110/15b area, however no comprehensive mapping had been carried out on existing data. On being awarded the Licence, BHP Billiton purchased 1469km of 2D seismic data over the 110/15b block and surrounding areas (Figure 1). A 2D seismic mapping effort was then undertaken at both the Triassic Ormskirk level, as well as the deeper Permian Collyhurst levels to evaluate prospectivity. This mapping failed to identify or firm up any tangible leads on Block 110/15b, particularly in the absence of 3D data. As such the planned follow-up reprocessing effort was not initiated, and the license was relinquished at the end of Year 2 Promote Licence term. 3 Exploration Activities Data that were used in the evaluation of the 110-15b block included the H92-110-15, HEX-85, M90-110- 15, 95-110-15, SC87-S, SC87-C, H93A and BG923 2D surveys (Figure 1). These data were incorporated into mapping efforts undertaken at the Ormskirk and Collyhurst levels (Figure 2). The Ormskirk interval is the proven hydrocarbon reservoir at the nearby Lennox Field, while the Collyhurst interval is unproven in Liverpool Bay (the main risks being reservoir effectiveness and seal). 4 Prospectivity Analysis The notional leads over the 110/15b area proposed in the pre-license round anaylsis have not progressed to mature status. Structural mapping at the Ormskirk level in the footwall to the Lennox field (Figure 3a) shows a run of dip to the north which ultimately sub-crops at the seafloor. An example of the data quality (Line H92-110-15-17) is shown in Figure 3b. Within the hangingwall to the main Lennox fault (part of the Formby Fault system) there may be potential for very small fault dependent closures, however these remain high risk and sub-economic on the current 2D dataset. Similarly, at the Collyhurst level, mapping shows that in the footwall to the Formby Fault there is no structural closure over the 110/15b block (Figure 4). As for the Ormskirk level, there is no recognised prospectivity within the hangingwall area. In addition, there is no proven seal mechanism for the Collyhurst play within the licence area. Given the results of this prospectivity analysis, reprocessing of the existing 2D data would not provide any significant benefit. Issue Date: 25/01/2010 2 of 7
5 Reserves Summary No additional resource potential is recognised within the licence area. 6 Clearance BHP Billiton Petroleum gives permission to publish the relinquishment report 7 Maps and Figures Issue Date: 25/01/2010 3 of 7
Figure 1. 2D seismic data over the greater 110-15b licence area Issue Date : 25/01/2010 4 of 7
Figure 2. Stratigraphy of the southern Liverpool Bay area Issue Date: 25/01/2010 5 of 7
Lennox Field H92-110-15-17 110-15B License area Figure 3a. Top Ormskirk TWT structure Figure 3b. Seismic line H92-110-15-17 showing near Top Ormskirk Horizon (yellow). Line location shown in Figure 3a. Issue Date: 25/01/2010 6 of 7
Lennox Field 110-15b Figure 4. Near Top Collyhurst TWT Structure Issue Date: 25/01/2010 7 of 7