Cameron 27 is a vertical coal seam gas exploration well initially operated by Pure Energy Resources Limited (now QGC Pty Limited) in ATP 852P (currently located in PL 498). Refer to Figure 1. The aim of the well was to target, evaluate and production test coal seam gas in the Upper and Lower Juandah Coal Measures of the Walloon Subgroup Coal Measures (WCM). Cameron 27 was spudded on the 17th November 2008 by JD Drilling’s JD 17 rig. The 17” conductor section was drilled to 15.30 m RT, then the 13 3/8” conductor was set and cemented at 15.30 m RT. The 12 ¼” surface section was drilled to 69.93 m RT, then the 8 5/8” surface casing was set and cemented at 68.93 m RT. The 7 7/8” production section was drilled to a total depth of 370.07 m RT in the Lower Juandah Coal Measures on the 21st November 2008 and encountered coals in the Upper and Lower Juandah Coal Measures. One wireline log was conducted, and then 6 5/8” slotted production casing was placed from 66.10 to 370.07 m RT. Prior to suspending the well completion strings were installed, comprising a NOV 120-1200 PCP and lower completion 2 7/8” tubing string as well as an upper completion sucker rod string with end of tubing (EOT) at ~355.00 m RT. The well was suspended on the 24th November 2008 pending production testing. An account of the drilling and completion activities is contained in the Cameron 27 Well Completion Report (QDEX Company Report Number (CRN) 55711). After the drilling and completion phase was finished, production testing was conducted at Cameron 27. A description of this activity is included in the Well History (Section 2.2). No production, workovers, interventions, maintenance or additional drilling, wireline logging or cementing activities were conducted post the drilling and completion phase (except the P&A activities summarized below). Cameron 27 produced a total of 0.614 TJ (0.0165 MMm3) of gas and 0.662 Mega litres of water during a production test from November to December 2008 (QDEX CRN 78400). This legacy exploration well was no longer required although production from this wellpad area was still needed and a replacement well will be drilled with improved well design, as such Cameron 27 was plugged and abandoned. On the 17th August 2019, Easternwell Energy’s EWE #28 rig commenced abandonment preparations, by removing the upper completion rod string and then Weatherford (WFD) ran a multi-sense caliper (MSC) log in the lower completion tubing string to determine the bridge plug (BP) set depth. BP set at 341.00 m RT in the tubing, pressure tested, and then the PCP and lower completion tubing string was removed. WFD ran an MSC log in the surface and production casing to ascertain the internal casing details followed by a Gyro Survey, prior to installing a suspension (kill) string including a BP at 46.20 m RT which was successfully pressure tested. Secured well and rig released. On the 26th November 2019, Easternwell Energy EWE #28 mobilised to Cameron 27 for the purpose of replacing the wellhead, removing the top part of 6 5/8” slotted production casing and emplacing downhole abandonment plugs in the surface casing. EWE #28 rigged up, gas tested wellhead area (0.0% LEL), removed kill string, set a BP at 58.17 m RT, then during pressure testing observed a leak between the old B-Section and casing stump. Set another BP at 39.46 m RT as an additional barrier, replaced the old B-Section with a new 8 5/8” LRC B-Section and successfully pressure tested surface casing and new wellhead assembly above an inflatable packer at 5.90 m RT. Milled top of 6 5/8” production casing to 66.84 m RT, then cut 6 5/8” production casing at 75.10 m RT prior to multiple unsuccessful attempts to retrieve the fish to surface. Unable to manipulate the fish through the LRC B-Section and BOP. Subsequently, Weatherford ran an SBT wireline log from 66.00 m RT to surface to evaluate the cement behind the surface casing across the Springbok / WCM boundary and its isolation barrier integrity. Weatherford then set an 8 5/8” BP in the surface casing and tagged it at 60.53 m RT with the available rig string weight although was unable to achieve a successful pressure test. WellPro CMTU #2 placed cement plug 1 and two cement top-ups from the BP to 4.59 m RT, all of which were tagged with the maximum available rig string weight. Multiple pressure tests on each of the two cement top-ups were unsuccessful. Further investigation continued and during pressure testing a leak was observed between the conductor and surface casing when the pressure was above 300 psi. Well pressures were monitored over the next ~24 hours to ensure that there was no pressure build up in the well, after which the well was secured and rig released. Wellhead pressure and gas levels at Cameron 27 were monitored monthly for 6 months up to June 2020. Prior to commencing the upper wellhead abandonment, a routine daily surface gas test indicated 0% LEL and 0.0 psi at the wellhead. The surface abandonment occurred on the 11th August 2020, when the wellhead was excavated, casing strings cut at 1.65 m GL, removed, cement placed to from TOC to top of casing cut, capped, buried and P&A signage installed above the well. Expanded descriptions of each of these activities is included in the Well History (Section 2.2), with corresponding details contained in relevant Tables and Appendices. Cameron 27 was plugged and abandoned in accordance with the ‘Petroleum and Gas (Production and Safety) Regulation 2004’ and ‘Code of Practice for the construction and abandonment of coal seam gas and petroleum wells, and associated bores in Queensland Petroleum and Gas Inspectorate Version 1 September 2018’.