In early June 2018, Petrobras disclosed that the 3BRSA1305ARJS being tested in the Mero portion of the pre-salt Libra Field of the Santos Basin produced at a rate of 50,800 boe/d in April and was the most productive well in the country easily surpassing the 8LL87DRJS in Lula Field with 39,400 boe/d and the 7SPH17SPS well in the Sapinhoa Field in third place with 38,400 boe/d. The increased rate of production for the Mero test is associated with increased gas injection in the reservoir started in February by an injector well. Test production in the Mero portion of Libra Field began in November 2017 with a flow restricted by gas flaring of about 18,000 bo/d between December and January. In February the forecast after the startup of the injection well was expected to reach 40,000 bo/d. In April, oil production was around 36,000 bo/d. Currently the FPSO Pioneiro de Libra has been testing in the Mero 2 and Mero 3 areas of the field and by year end Petrobras will have started testing a new well in the Mero 1 area. On 31 January 2016, Petrobras finished drilling operations on the the 3BRSA1305ARJS replacement appraisal in the pre-salt Libra Field of the Santos Basin and the rig moved to another location. The well was spud on 25 May as a second attempt to drill this appraisal and on 29 October 2015 filed an oil show report with the ANP. The previous drilling attempt ended drilling on 24 May 2015 and was assumed to be junked and abandoned. The 3BRSA1305ARJS is the third appraisal drilled at Libra and has a planned total depth of 5,874m. It is located in 1,951m of water and was drilled in the western end of the field by the West Tellus drillship. The presumed targets were in the pre-salt Early Cretaceous Barra Velha and Itapema formations. Petrobras holds 40% working interest and operates the Libra consortium. Shell and Total each have 20% and CNOOC and CNPC have 10% each. The ultra-deep water Libra discovery is thought to be the largest pre-salt field in Brazil with a reserve estimate of 8 to 12 Bboe and one of the largest fields in the world. <P />
In early June 2018, Petrobras disclosed that the 3BRSA1305ARJS being tested in the Mero portion of the pre-salt Libra Field of the Santos Basin produced at a rate of 50,800 boe/d in April and was the most productive well in the country easily surpassing the 8LL87DRJS in Lula Field with 39,400 boe/d and the 7SPH17SPS well in the Sapinhoa Field in third place with 38,400 boe/d. 