Mumbai High Field, India
Bombay High (now Mumbai High) is an offshore oilfield located in the Arabian Sea around 160km west of the Mumbai coast. Discovered in 1974, the field has been operated by Oil and Natural Gas Corporation (ONGC). Production at the field started in 1976.
The oil field consists of two blocks named Mumbai High North (MHN) and Mumbai High South (MHS). The blocks were divided based on shale barrier assisting in independent exploitation of reserves at the north and south fields of Mumbai high.
Currently, the field has 1,659 million metric tons (MMT) and is producing around 12MMT a year.
The company's board granted approval for the second phase of Mumbai High North (MHN) Redevelopment project in January 2009.
Sudhir Vasudev, ONGC director said, "Phase II redevelopment of Mumbai High is going on. About INR 90,000m will be pumped into it over the next 3-4 years. It is a long-term programme."
ONGC announced its plan for Mumbai High redevelopment in 2000. It planned to spend around INR 90,000m in five years for redeveloping the field. The redevelopment plan has been divided into two phases. The first phase started in 2000 and was completed in December 2006.
The phase I is expected to yield an additional crude oil production of 23.25 MMT of crude oil and 6.10 BCM of gas by 2030, from 73 new wells and ten side track wells drilled.
The cumulative oil production from phase I redevelopment wells was 9.34MMT and cumulative gas production was 2.89BCM until March 2008.
The field reached its peak of production of 400,000bopd (barrels of oil per day) in 1985 and continued at same rate until 1989.
Decline in oil and gas production led to the need of a redevelopment plan. The production declined gradually and reached 220,000bopd in 2001 and 10 million metric standard cubic metres of gas per day (mmscmd or mmcmd).
ONGC invested around INR80,000m under phase I for enhancing the efficiency and controlling the decline in oil and gas production. Under phase I, 29% of 1,659 million tons of total reserves were improved.
Phase II redevelopment, announced in 2009, will result in an additional crude oil production of 17.354 MMT and Natural Gas 2.987 Billion Cubic Metres (BCM), totalling to 20.34MMT of oil equivalent by March 2030.
The phase II of MHN redevelopment plan targets to further enhance recovery rate from Mumbai High by focusing on drilling of 73 new wells and side tracking of 38 poor producers. The development of small reservoirs such as L-II and L-I has been combined with major reservoir L-III to strengthen oil production and development programme.
The second phase of Mumbai High North is expected to complete by September 2012 and cost of redevelopment will be INR 71,333.9m.
ONGC started construction of new process complex MHN near the old Bombay High North (BHN) platform during 2007. Due to a major fire in July 2005, the BHN platform was completely destroyed, which affected oil production. Along the field's redevelopment plan, the new MHN complex will also be developed handling around 255,000 barrels of liquid including 48,000 barrels of oil per day and 6.8mmcdm of gas.
The MHN process complex will consist of a process-cum-riser platform, a living quarter, a subsea-connected flare structure, subsea pipelines and adjoining topside modifications such as facilities for handling sour gas from B series marginal fields.
The new MHN complex project is expected to be complete by 2010 and will ensure optimised and safe operations at the project field.
L&T secured a $1.18bn contract from ONGC during August 2009. The contract includes an order for MHN processing platform and living quarter projects along with additional order for the supply of three process gas compression modules to be installed in MHN complex. The three compression modules constitute a total of 80,000 metric tons of structures. The scope of work includes surveying, engineering, procurement, fabrication, installation and commissioning of the facilities by L&T. The contract is expected to complete within 33 months.
New MHN process platforms will organise gas lift pipelines and oil exports lines of MHN field. The former BHN platform will be replaced by new MHN process platform, and will create additional facilities for gas processing from future platforms. MHN will have a well fluid capacity of 23,877 b/d of oil and 2.56mmcmd of gas.
To facilitate interconnectivity of the power generating system, an installation of high voltage submarine composite electrical cable as grid interconnectivity project was initiated in 2007. The installation will cost around INR 7,400m and is expected to complete by March 2012.
Laying submarine electrical cable to interconnect 26 well head platforms, electrical submersible pumps (ESP) 81 wells and associated surface facilitates are the components of grid interconnectivity. The ESP will assist in oil production from high water cut (90-95%) wells of Mumbai high field.
The board of company approved proposal for investment INR39,900m in "C series" development project in 2007. The investment will facilitate at Mumbai High (North) process in handling additional 3.0mmscmd of gas from "C series" wells.
ONGC approved construction of 7 pipelines with risers and associated top-side facilities in Mumbai High North in April 2007. It will involve investment of around INR 3,550m. These pipelines are vital for optimum utilisation from Mumbai High. It will be connected to new MHN complex and is expected to be complete by April 2010.
The Bombay High field was discovered in February 1974. The Russian and Indian team from seismic exploration vessel Academic Arkhangelsky discovered the Mumbai High while mapping of the Gulf Cambay during 1964-1967.
The discovery of Bombay High with subsequent other discoveries of oil and gas fields in western offshore changed the oil scenario of India.
Geology and oil reserves
Different oil and gas reservoirs namely, L-I, L-II, L-III, L-IV, L-V, basal clastics and fractured basement from top to bottom are present on the Mumbai High project field. L-II and LIII are primarily the limestone oil reservoirs of Miocene age, further classified into several layers.
Bombay High has in place around 1,659 million tons of total reserves.
The project field reached its peak production level in 1998 with 20MMT a year. Mumbai High, along with its adjoining fields, produces 12.8mmscmd of gas.
The production was around 265,000bopd with an average 63% of water cut and an average production of 1200 barrel of liquid per well during 2007.
The cumulative production of crude oil including results of phase I development was 140.25MMT until January 2009.
The field is exploited using the gas lifts method, a major artificial lift method used for oil production. Several gas compressors spread over the number of process complexes in the field to support the broad gas lift network.
ONGC envisages a total crude oil production of 202.42MMT by 2030. The company is trying to improve the recovery rate by 40% by 2040. Further, the field will require additional liquid production with an 80% water cut in 2015 and a 95% of water cut by 2025.
ONGC is installing electrical submersible pumps in 81 oil wells in the field. The ESP installation is scheduled to complete in March 2012 and will increase the oil and gas production levels by 5.21MMT and 0.79 billion cubic metres respectively by 2024.