KG Field is a HPHT field in the Krishna Godavari basin in the Bay of Bengal, offshore north east India. The field has been extensively appraised by 15 wells to date.
The field is:
- Extremely tight (k < 1mD)
- An Overpressured gas bearing sandstone formation with bottomhole pressure and temperature of 12, 000 psi and 400 °F at 4, 500m TVDSS
- Containing corrosive, relatively dry gas (CO2and H2S content of 7%and 100 ppm respectively) with a condensate gas ratio (CGR) of 10 bbl/MMSCF
Located 120km offshore in 100m depth
Nautec Energy Solutions (Nautec) was contracted to provide the detailed well construction and completion design for the HPHT development wells.
- The selection and specification of equipment for production casing & tubing, Metallurgy, and downhole completion
- Preparation of the forward activity workscope required to mature the development of any deepwater discoveries in the block: a scoping schedule, cost forecasts for subsea well construction
An overall field development plan which integrated well construction activity with surface facilities/product export options
Well configuration ie high angle/horizontal vs low inclination has the potential to reduce the number of wells required to develop field. High angle/horizontal wells achieve this due to the potential provision of acceleration economics benefit without compromising ultimate recovery.
Nautec delivered a completion design using proprietary Metallurgy for well tubulars.
The HPHT conditions, combined with corrosive reservoir fluids, demands use of high strength alloy steels for well tubulars, especially for the production casing and tubing.
The low permeability of the reservoir is offset by high pressure. However, sustainable commercial rates (min. 30 MMSCFD) required high angle/horizontal wells through the reservoir. This helped to avoid the need for hydraulic fracturing.
To meet the required well productivity, long sections through the reservoir provide the most cost effective method. However, if this does not achieve the desired results, fracture stimulation may be required. Treating pressures for such operations become extremely high and well costs will increase significantly.