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Conversion of Drilling Rig to Hybrid Rig for clean environment Author: Keshab Chandra Paul, DGM(Elect.) e-mail id: [email protected] +91 9402141044 Co-Author: Sushil Kumar, SE(Elect.) e-mail id: [email protected] +91 9436501050 Abstract Brief about the project and aim Present Drilling Rigs are running on Four (04) numbers DG (Diesel Generator) sets of 1430 KVA each consuming approximately 82.91 Kiloliters of Diesel and 596 Liters of Lube oil per Month, generating approximately 324274 kWh of Electrical energy (as per historical data of Drilling Rigs of ONGC, Tripura asset, Agartala). The total running cost of these DG sets calculated as per last three years records, comes at a whopping ₹58,35,780.00 per Month (all data’s and calculations would be provided along with the full technical paper) . ONGC owns significant natural gas reserves in the North Eastern state of Tripura. The complexities of logistics and attendant costs limit the economic viability of transportation of gas to other parts of the country. In order to optimally utilise the gas available in Tripura, ONGC has developed (with 50% stake) a 726.6 MW Combined Cycle Gas Turbine (CCGT) thermal power plant (ONGC Tripura Power Company Ltd - OTPC) close to its gas fields in the state of Tripura. OTPC produces surplus power and feeds it to Tripura State Electricity Corporation Limited (TSECL), which is further supplied to the deficit areas of North Eastern States of India. This project aims at giving the option of running the Drilling rigs on external power supply fed from state electricity board in addition to present DG sets. Recently, India has signed Paris agreement for climate change for reduction of consumption of fossil fuel for clean environment. This project for conversion of Drilling Rig to Hybrid Rig is for clean environment in support of the Paris agreement. This project not only contributes towards clean environment and carbon credit but also gives huge monetary benefits to the three Government Enterprises viz. ONGC, BHEL & TSECL. Details of the project are mentioned below. Detailed conversion process The conversion would be done by installation of movable substation, comprising of one step-down transformer of rating 4 to 5 MVA, 3 phase, 11 KV / 600 Volt / 440 Volt, 50 Hz. This sub-station would be fed electrical power from Tripura State Electricity Corporation Limited (TSECL) through 11 KV transmission lines and the output of the substation would be 1 hooked to AC-PCR & DC-PCR through bus tie or bus coupler. The incoming transmission lines would be laid very rapidly by TSECL, exclusively for the Drilling rig, for which plan would be made in advance. Technical discussion was held with BHEL (OEM of the drilling rig) representatives regarding the project and BHEL has agreed to develop suitable customized movable sub-station with safety arrangements as per IE rules and DGMS guidelines. Installation and commissioning part would also be in BHEL’s purview. Technical discussion was also held with Director (Technical) of TSECL. Director (Technical) of TSECL has appreciated the proposal and agreed for full support & corporation for providing 11 KV power from available nearby substation to the drill-site locations of drilling rig. This would be the best way to monetize the surplus power generated from OTPC. The layout & circuit diagrams after conversion of rigs are as below, External power supply Modified Layout Diagram of E-1400 series Rigs Modified Circuit Diagram of E-1400 series Rigs 2 Cost implications of the project Cost implications of the project are not yet calculated, but BHEL has agreed to give technical support and required material for this pilot project. However roughly the project cost is estimated to be below ₹ One Crores per drilling rig. Benefits of the project This project would be beneficial in many ways such as, - Reducing carbon emission. Reduction in global warming. Earning of carbon credits. Noiseless operation at the Rig. Relief to nearby habitations. Adherence to Paris agreement of climate change. Huge monetary benefit. Cost benefit analysis is calculated as under, Cost benefits analysis: Cost of running 4 no’s of DG sets per Month per drilling rig = ₹58,35,780.00 (considering costs of High Speed Diesel burned, Preventive maintenance cost, breakdown maintenance cost and depreciation of capital cost of DG sets). Total cost per Month for getting 324274 kWh of Electrical energy considering per unit rate of ₹7.00 (1 unit = 1 kWh) from external power source plus depreciation of capital cost of the project = ₹22,69,918.00 + ₹2,08,333.00 = ₹23,74,084.00 (approximately 40.68 % of existing setup) I.e. a saving of approximately ₹34,61,696.00 per Month per Rig. Which when implemented in all three Drilling Rigs of ONGC, Tripura asset would be a mammoth ₹12.46 Crores (approx.) per year. The above cost benefit calculation is on the basis of 100% utilization i.e. consumption of electrical power from the external source. The actual calculation would be on pro-rata basis i.e. if 50% power is self-generated at the Rig & 50% is taken externally, cost benefit would be approximately ₹17,30,848.00 per Month per Rig. 3