Empyrean Energy, partner of operator Conrad Petroleum in the Duyung PSC, located offshore in the West Natuna Basin, reported on 25 October 2019 that appraisal well Tambak 2 has encountered gas kick while recovering a failed packer. The well was immediately shut-in and killed using heavy barite mud. Two separate DSTs were then conducted, however no flow was encountered at surface due to formation damage caused by the significant quantity of heavy mud lost in the highly permeable Intra-Muda Formation reservoir (calculated permeability around 200 mD to 3 D).  According to the operator, in absence of formation damage, the DSTs would have likely flowed at similar rates as the earlier Mako South 1 well.  The operator's next step is to drill Tambak 1, targeting to further appraise the Intra-Muda Formation and to test the deeper Gabus Formation.  Tambak 2 reached TD at 503 m TVDSS (1,650 ft TVDSS) on 12 October 2019. The operator acquired pressure surveys, wireline logs and conducted coring programme, and confirmed the well as a successful appraisal for the Mako field. Following logging and coring, the operator was preparing to conduct the DST programme on the well.  Reportedly, the reservoir is a well-developed sand unit with good porosity and permeability. Thickness of the reservoir is approximately 9.8 m (32 ft), based on log readings. Reservoir top came in as predicted at 381 m TVDSS, about 3 m up dip from Mako South 1 well. Gas-water contact interpreted from logs is at a depth of 392 m TVDSS (1,286 ft TVDSS), similar to that shown in Mako South 1 well, indicating the large areal extent of the Mako field.  Tambak 2 was spudded on 4 October 2019. On 24 September 2019, Empyrean Energy reported that the rig contractor COSL had mobilized its "Asian Endeavour 1â jackup to the well location in preparation for the drilling programme.  Tambak 2 is the first of the two wells planned in the current exploration drilling campaign, the other being wildcat Tambak 1. Each well will need an estimated 33 operating days including testing, with a gross total cost of around USD 17-USD 19 million, including testing.  Tambak 2 (formerly Mako 2) is drilled to appraise the southern area of the Mako field, targeting the shallower pay zone in the Pliocene intra-Muda Formation sandstones, on the crest of the Mako structure. The reservoir was expected to be intersected at a depth of 380 m TVDSS and the well final depth was planned at 595 m TVDSS. The well has been estimated to hold prospective resources of approximately 100 Bcfg. GCOS for this well is estimated at 75%. The testing programme will include coring, logging and open hole testing of the intra-Muda Formation target. Tambak 2 is located 13.5 km southwest of the previous appraisal well Mako South 1, drilled in 2017.  Wildcat Tambak 1 will be targeting the Tambak (formerly Mako Deep) prospect, a deep structural closure located beneath the Mako gas field, as well as appraising the shallower intra-Muda Formation sandstones in central area of Mako field. The shallow Muda objective is anticipated to be intersected at approximately 385 m TVDSS, and the planned total depth for the well is 1,370 m TVDSS.  The Tambak prospect is a three-way dip closed inverted anticlinal structure (estimated 15 sq km in area) with the primary target in the fluvial lacustrine sandstones of the Oligocene Lower Gabus Formation, charged by the syn-rift source rock of Benua shale. Direct hydrocarbon indications have been identified in the structure from the reprocessing of existing 2D seismic data. Prospective resources for Tambak are estimated between 200 and 300 Bcfg, with mid-case resources of 250 Bcf and geological chance of success (GCOS) of 45%.  In late April 2019, the operator and partners (Empyrean Energy and Coro Energy) announced the agreement to the planned drilling programme in the block.   A third-party review by Gaffney Cline & Associates has estimated gross 2C recoverable resources of 276 Bcf of dry gas for the Mako field, with upside of 3C resources at 392 Bcf of gas. In the event of positive results from appraisal drilling, the 3C resources could be potentially moved to the 2C category, and likewise the 2C resources to 1C.  A Plan of Development (PoD) for the Mako field was approved in Q1 2019, shortly after the conversion of the Duyung PSC to Gross Split fiscal terms on 17 January 2019. A Heads of Agreement with a Singapore buyer for gas sales from the Mako field is in place, pending final Gas Sales Agreement.  In February 2019, Coro Energy has agreed to acquire a 15% participating interest in the Duyung PSC from Conrad and Empyrean, which were holding 90% and 10% respectively, through operating subsidiary West Natuna Exploration Limited (WNEL). Upon final approval of the transaction, subject to regulatory approval, interest holders in the Duyung PSC will be Conrad (76.5%), Empyrean (8.5%) and Coro (15%) via direct ownership, as WNEL will transfer all of its interest to the respective companies.  The total consideration payable by Coro includes USD 4.8 million (consisting of USD 2.95 million in cash and USD 1.85 million in Coro shares), plus a contribution of USD 10.5 million to partially fund the 2019 exploration drilling programme.  The initial payment (USD 1.75 million in cash, plus USD 1.2 million towards the 2019 drilling campaign) was made by Coro in February 2019 upon signing the sale and purchase agreement. The balance payment (USD 1.2 million in cash, USD 9.3 million for the drilling campaign, plus the issuance of 60,905,037 new Coro shares with a value of USD 1.85 million) was made in April 2019.  Background Information  The earliest well drilled within the Duyung PSC area, Conoco's 1975 Tenggiri 1 wildcat, was plugged and abandoned with gas shows in its then South Natuna Sea Block B area. The well is located on crest of the Pliocene boundary high in the north-eastern part of the Duyung block.  The Cumi-Cumi PSC, originally covering an area of 4,970 sq km, was originally awarded to Lasmo as 100% equity holder on 20 May 1991. The contract was awarded on the basis of payment of a total signature bonus of USD 3 million and commitment to a 10 year work programme of USD 34 million.  In September 1996, Lasmo plugged and abandoned Cakalang 1 at the eastern end of its Cumi-Cumi PSC after reaching TD at 1,372 m in the Lower Gabus Formation. Only minor gas shows were reported.  Commitment wildcat Mako 1 was spudded on 26 February 1999, about 4 km east of Cakalang 1. Mako 1 was abandoned with gas shows on 6 March 1999. The well was a prognosed 484 m test for shallow gas in the Intra-Muda Formation and reached TD at 486 m. Mako 1 encountered about 7 m gas-bearing sandstones from logs, but the well was not tested.  Following the disappointing results of Mako 1, the Cumi-Cumi PSC was relinquished in 2000.  The Duyung PSC was awarded to Transworld (100%) in January 2007. The block was offered under the direct mechanism during the second phase of the "Fifth Round" of Migas-controlled acreage releases which opened on 15 August 2006. A signature bonus of USD 1.5 million was paid and firm commitments included G&G studies worth USD 1 million, acquisition of 400 sq km 3D seismic data and drilling one exploration well. The seismic commitment was conducted from late 2008 to early 2009 using PGS's 'Orient Explorerâ vessel. Around 360 sq km of data was acquired.  In September 2015, WNEL had agreed to farm out 85% interest to Hague and London Oil, however the agreement was terminated as of 1 April 2016 due to lack of the necessary regulatory approvals.  On 12 May 2017, Empyrean reported the completion of the first stage of a proposed deal with Conrad Petroleum for the acquisition of a 10% stake WNEL for an initial consideration of USD 2 million, pursuant to a Sale and Purchase Agreement (SPA) signed on 4 April 2017. Under the terms of the SPA, Empyrean had the option to pay further cash consideration of USD 2 million that would grant the company an additional 10% interest in WNEL. However, Empyrean reported on 30 May 2017 that it would not proceed to acquire the additional 10% interest, thus retaining only the initial 10% stake in WNEL while Conrad Petroleum retained the remaining 90% stake plus operatorship.  The Mako structure is estimated to have a lateral extent of 304 sq km with tested reservoir of approximately 7 m of fine sand layer within the Intra Muda Formation. In August 2018, Empyrean reported that modeling studies on the field indicated estimated gas initially in place (GIIP) of 705 Bcf, with upside potential case of 1,317 Bcf. The company at the time also reported recoverable contingent resources of 433 Bcf (2C) and 646 Bcf (3C).  Mako South 1 was spudded on 16 June 2017, drilled using the âCOSLSeekerâ J/U. The well reached a depth of 1,330 feet (approximately 405 m) on 19 June 2017.Â The well was completed on 5 July 2017. The operator continued to evaluate the test results, core and other downhole data after drilling. According to the operator, test results indicated a laterally continuous reservoir with permeability in the order of multi-Darcy.
Empyrean Energy, partner of operator Conrad Petroleum in the Duyung PSC, located offshore in the West Natuna Basin, reported on 25 October 2019 that appraisal well Tambak 2 has encountered gas kick while recovering a failed packer. The well was immediately shut-in and killed using heavy barite mud. Two separate DSTs were then conducted, however no flow was encountered at surface due to formation damage caused by the significant quantity of heavy mud lost in the highly permeable Intra-Muda Formation reservoir (calculated permeability around 200 mD to 3 D). 