(Sharecast News) - Caspian Sunrise updated the market on operations at its flagship BNG asset on Wednesday, following its announcement that the interval of interest at Deep Well A8 extended 110 metres from a depth of 4,346 metres.The AIM-traded firm said that since that announcement on 7 June, it had drilled to a depth of 4,520 metres, below the intended casing point, as the drilling revealed the identified interval extended further than previously detected, with oil bearing rock present to depth of 4,501 metres, an interval of 155 metres, based principally on core samples.It said that, using more detailed and reliable wireline logging across the full depth of the interval, it now understood the interval identified extended from a start point of 4,342 metres to a depth of 4,501 metres, in total 159 metres, of which 52.2 metres was porous, oil saturated rock.Caspian Sunrise had previously reported its estimation that the surface area for the identified interval extends across the full 58 square kilometres of the Airshagyl structure."Casing is now being run to a depth of 4,520 metres, where it will be set and cemented, following which we intend to continue to drill towards the next expected interval of interest believed to be at a depth of approximately 5,200 metres," the board said in its statement."The planned total depth of the well remains for the present at 5,300 metres, which we expect to reach by the end of August."At Deep Well A5, the company said that in preparation for a new sidetrack, milling of the liner hanger was continuing at a depth of 3,900 metres.Removal of the liner was expected to create sufficient working space to drill a new side-track from below the salt layer.To date, 1.6 metres of the liner hanger had been successfully milled away, leaving a further one metre to remove.Milling work was expected to take another seven to 10 days, at which time a laser would be used to cut the surplus liner, which the company would then attempt to pull from the well.At Deep Well A6, Caspian Sunrise said a 100-tonne crane was on site to position a more cost-effective rig over the well, in readiness to first complete and waterproof the bottom of the well and then to re-perforate the well."The workover [is] expected to commence by 1 July, and will include squeezing cement near the bottom of the well to ensure the wellbore is isolated from any water deeper in the well, reperforation of the lower most prospective interval, and then clean up and testing."Once the bottom of the well is watertight the pressures present at the intervals of interest are expected to be lower than at the times of earlier attempts to penetrate the well, thereby making the re-perforation work easier."The company said it then intended to perforate the lower most prospective zone over two intervals - a six metre interval between depths of 4,447 and 4,453 metres, and a 19 metre interval between depths of 4,479 and 4,498 metres.Finally, at Deep Well 801, the firm said it was continuing to await the sourcing by its international contractor of a more powerful coil tubing unit with which to clear the well."The larger than previously detected interval at Deep Well 8 is clearly a significant development and very good news," said Caspian Sunrise executive chairman Clive Carver."The collective test results from the deep wells on the Airshagyl structure, A5, A6 and now A8, indicate the existence of a potentially very significant oil bearing structure."