Caspian Sunrise has a 99% interest in the BNG contract area, which is located in the west of Kazakhstan, 40 km southeast of Tengiz, on the edge of the Mangistau Oblast, covering an area of 1702km².

Shallow wells

MJF structure

The MJF structure is the best performing of the three potential shallow structures identified at BNG. The MJF structure has capacity to produce at the rate in aggregate of some 1130 bpd of oil from three wells, including more than 600 bpd of oil from the initial well 143.

Well 143 was drilled in 2013 to a depth of 2750 m to explore a potential new structure. After delays to clear the well of excess drilling fluid, Caspian Sunrise tested the well at five separate intervals, with the well currently producing at the rate of 610 bpd of oil using an 8 mm choke.

Wells 141 and 142 were subsequently drilled to depths of 2500 m to assess the extent of the MJF structure. The results of work to date has confirmed that the extent of the structure to be at least 10 km².

In May 2017, Caspian Sunrise announced the spudding of well 144, with a planned total depth of 2500 m, targeting the same Jurassic Callovian sands at a depth of 2200 m.

Caspian Sunrise has reported that the well was drilled to total depth without incident. Four intervals were perforated for flow testing. The first interval tested is flowing at the rate of some 1000 bpd of oil using an 8 mm choke. Our plan is to proceed with a long-term testing to evaluate the well potential.

Well 144 is located some 0.89 km from well 141 and some 2 km from well 143, which is believed to be near the centre of the MJF structure. Success at Well 144 significantly extends the size and value of the MJF structure beyond the 10 km2 previously assessed.

Potential new structure

With well 808, Caspian Sunrise has explored a potential new structure, targeting Cretaceous Jurassic and possible Triassic horizons. If successful, the new structure has the potential to rival the success of the MJF structure.

As previously announced, well 808 was spudded in January 2017 and drilled to a depth of 3200 m in March 2017 without incident and six intervals of interest identified.

Caspian Sunrise has previously announced the lower intervals tested between 3038 - 3030 m, with between 3014 and 3008 m containing shows of oil films but tested water with gas and are not considered worth pursuing. However, the company now believes that there may be a leak in the well casing, thus resulting in water inflow.

Once the casing has been assessed, and repaired if required, Caspian Sunrise will retest the lower intervals and also the remaining intervals between 2714 - 2716 m; 2646 - 2648 m; 2557 - 2559 m, and 2356 - 2363 m are planned for perforation and testing.

In the event, the results of testing the remaining intervals at well 808 indicated the presence of a significant quantity of oil a further two wells are planned for later in 2017.

South Yelemes structure

The South Yelemes structure was first identified as an oil producing structure during the Soviet era. During Caspian Sunrise’s involvement with BNG three new shallow wells (805, 806 and 807) have been drilled and in aggregate these have produced at the rate of 150 bpd of oil.

Deep wells

Deep well A6

Deep well A6 was the third deepest well drilled. Lessons were learnt from the earlier wells and, with the exception of delays penetrating the salt layer, the drilling of the well was less eventful than for either deep well A5 or deep well 801.

Analysis of mud and wireline logs has shown the presence of a hydrocarbon bearing reservoir with a vertical column potentially in excess of 100 m. In January 2017, the lower 46 m were poorly perforated although the limited recoveries tested with oil films, water and gas.

In April, the top 60 m of the interval were successfully perforated using a different leading international contractor. While the results of limited testing to date have been inconclusive, Caspian Sunrise’s management believes that the pressure in the well has limited to impact of the perforation work undertaken to date. Further perforation work is planned in July, following which the well will be assessed for flow testing.

Deep well A5

Deep well A5 was the first of the deep wells to be drilled and like deep Well A6 has been drilled on the Airshagyl structure. The well has produced for a few hours at the rate of 2000 bpd of oil, but it has not yet flowed sufficiently for a prolonged well test.

Extreme high pressure and temperature resulted in a difficult drilling phase, which led to the initial decision to test the well on an open-hole basis. Caspian Sunrise no longer believes that an open-hole test is the best way forward and have decided to side-track from a depth of 4000 m, following which the company would hope to be able to conduct the flow test.

The work to allow the side track to commence was planned using a 40 t ZJ-40 rig. As the work programme advanced, it was clear that an excessive and possibly dangerous strain was being placed on the rig’s engines. According it was decided to stop the work and use a heavier 50 t RT-50 rig.

The previous rig has been dis-assembled and the new rig assembled and is expected to become fully operational shortly, following which work on the planned the side track will resume.

 

Clive Carver, Executive Chairman of Caspian Sunrise, commented: “Caspian Sunrise is naturally delighted with the early results from well 144, which should materially increase the proven size of the structure and increases our aggregate production capacity to well over 2000 bpd of oil. The company looks forward to determining whether the new structure demonstrates it is on a par with the MJF.

Read the article online at: https://www.oilfieldtechnology.com/exploration/03072017/caspian-sunrise-provides-bng-operations-update/