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Safety Measures Adopted in Underground Cavern Storage of Crude Oil to Prevent Disasters by Rajan K Pillai, CEO ISPRL 31 st January 2014 Slide 2 CONTENTS OF PRESENTATION 2 Underground Rock caverns for storage of hydrocarbons in India Risks and Hazards in Underground Caverns o Construction Risks. o Operations Risks. Mitigation methods o Construction phase o Operations phase Slide 3 Underground Rock caverns for storage of Hydrocarbons in India Slide 4 Access Ramp (AR) Upper Connection (UC) Intermediate connection (IC) Upper Shaft Connection (USC) Access Shaft (AS) Operation Shaft (OS) Lower Shaft Connection (LSC) Water Gallery Operation Shaft Connection (WOC) Water Gallery Access Shaft Connection (WAC) Water Curtain Gallery (WCG Sump which houses the submersible pumps Lower connection (LC) Isometric drawing of SALPG Cavern Operation Shaft is 201 meters deep Slide 5 The Isometric View of the Visakhapatnam UG Facilities Total tunnelling including shafts exceeds 7 kilometres Capacity is 1.33 MMT The view shows the various parts of the facility which includes access tunnels, water curtain galley, interconnection tunnels & shafts. Slide 6 Isometric View of Mangalore UG Facilities Total tunnelling including shafts exceeds 9.2 km. Capacity is 1.5 MMT The main galleries are 913 m long Slide 7 Isometric View of Padur UG Facilities Total tunnelling including shafts exceeds 13.7 km(only top heading). The Padur project capacity is 2.5 MMT. The total excavation is in excess of 36.8 lakh cu m. The facility has 6 storage galleries that are 700 m long and 2 storage galleries that are 650 m long. A jumbo jet in the foreground for comparison Entire excavation has been completed Slide 8 8 m Top Heading Bench 1 Bench 2 Bench 3 7 m Varies Typical Cross Section of the Main Cavern The height of the caverns is almost equivalent to a ten storey building Slide 9 Photograph of a gallery in the Visakhapatnam Cavern A view of the Padur Cavern Gallery The galleries are 30 meters tall and 20 meters wide. There are eight galleries. Six galleries are 700 meters long and three are 650 meters long. This photograph is of one of the completed 700 m gallery Slide 10 ItemVizagMangalorePadurTotal Access & Connect. tunnels (meters)1632184734296908 Water Curtain Tunnels (meters)1804356038819245 Main Cavern (meters)32503572563212454 Shaft lengths (meters)4052325801217 Total Chainage (meters) 709192111352229824 Borehole Nos2754895141278 Borehole length (kilometers)17.232.026.976.1 Excavated qty in Million tons 5.46.39.821.5 Quantum of Excavation in ISPRL Caverns The excavated rock debris can fill 2.5 million standard 10 ton trucks Slide 11 ItemVisakhMangalorePadurTotal Concrete in Cu. m 5046435862914231,77,749 Shotcrete in Cu. m 37395217783507294,245 Rock Bolts in tons 23601981.722266,568 Reinforcement steel in tons 18101565699110,366 Explosives used in tons2330210038658,295 Approx Quantum of Material used in ISPRL Projects The material would required a huge transport fleet for movement from one spot to the other within the sites. In addition to the materials, workforce also needs to be moved Slide 12 Comparison of the Excavation Progress Curves Projects were started on different dates, but for comparison, zero dates have been matched Slide 13 Risks and Hazards in Underground Caverns Slide 14 Geological Risks- During Construction. Slide1 Over breaks and rock fall are major safety concerns during construction and can cause fatalities and can drastically slow down progress. Over Breaks and Rock falls Slide 15 This bench was excavated Since this fault was below the bench it could not be identified. Slide 16 Wedge on the wall started sliding When the bench was removed the rock wedge started sliding Slide 17 Almost 10,000 tons of rock came crashing down and resulted in one fatality. Slide 18 Area of brittle fracture The triangular block which slid down Smooth face Slide 19 Man standing near rock slide area Weakness zone, consisting of highly sheared and disintegrated material Slide 20 Slide 21 Geological Risks- During Construction. Slide3 Water bearing zones or aquifers zones could result in large water ingress into the caverns or shafts. Such a problem was encountered in the SALPG cavern project. Water ingress into shaft Underground Aquifers Slide 22 Large seepage of water into the Padur cavern during construction Slide 23 Traffic Hazards- a major concern during construction Large number of equipment required for excavation of the caverns. Movement of equipment adds to the risks Slide 24 Equipment handling during Construction Slide 25 Drilling & Blasting Method of Excavation Holes are charged with explosives after drilling and controlled blasting carried out Jumbo used for drilling holes in rock 25 Slide 26 Pull Drilling & Blasting Method of Excavation26 Slide 27 In ISPRL the quantum of explosives that have been used is huge. We have use approx 8300 tons of explosives in our projects. When handling such large quantities of explosives, there is the risk of accidental blasts or misfires. There is also the risk of the explosives being pilfered during their transportation and use and thereafter being used for undesirable activities. Explosives handling- a concern during construction Slide 28 The vibrations can be large if the quantum of explosives used is large. Vibrations can cause damage to the surrounding rock and effect the stability of the cavern. Vibration can also cause damage to surrounding surface structures. Blast induced ground vibrations can create social problems as they could disturb the people residing in the vicinity Vibration due to blasting another concern. Slide 29 Air borne dust particles when inhaled into the lungs can lead to various diseases, like bronchitis. There is particular concern that silica dust can lead to cancer. Crystalline silica is a common mineral present in sand stone, quartz and many other rocks During blasting operation fumes are produced. These fumes can be harmful to humans working inside the tunnels. The oxygen levels in the cavern can become low after the blasting operation and therefore poses a health hazard Fumes and dust a health hazard Slide 30 Loss of Containment Due to hydro geological reasons. Due to sabotage/failure of aboveground facilities Intermingling of different grades of crude oil. Fire/Explosions within caverns due static electricity discharge. 30 Risks During Operation Phase Slide 31 Mitigation Methods Slide 32 To ensure there is good stability of the cavern, rock bolts need to be installed and shortcrete applied. Poorer the rock strata, larger is the support requirement. Mitigation methods-Construction Phase Slide 1 Rock bolts Shotcrete Slide 33 Monitoring of the movement of the walls of the cavern using optical targets Large number of optical targets installed in the caverns. The bright spots are the optical targets Slide 34 Pre-Grouting in excessive water bearing zones Pre-Grouting involves drilling a number of holes on the face and pumping cement paste under pressure into them till sealing is achieved. High permeability and water bearing strata could result in higher grouting and slow excavation progress. Slide 35 The cavern access tunnels and junctions to be well designed. Only specialized equipment to be used for evacuating muck (equipment with all safety features) Drivers to be imparted specialized training for underground works. Tool box talk to be made mandatory before start of work. Housekeeping to be one of the important requirements in contract management. Good rewards and punishment system should be planned. Mitigation Methods for Traffic Hazards Slide 36 Obtaining all applicable Legal Permissions as per The explosive Act 1884 and Explosive Rules 1983. Putting in place a well defined explosive handling procedure and clearly describing steps to be followed during transportation, storage and handling of explosives. Ensuring qualified & authorized personnel only handle the explosives. Reconciliation of all explosive material and authentication of reconciliation statement by Magazine In charge. Mitigation Methods for explosives handling Slide 37 The vibration problems can be best controlled by having properly designed blast patterns. The number of blast holes, their length, amount of explosives to be charged and the detonation type. Once these parameters are controlled properly, they can reduce vibration levels drastically. After ensuring properly designed blast patterns, ensure the vibration levels are monitored on a regular basis. The site to be trained to ensure that only smooth blasting techniques are followed at all times inside the caverns. Mitigation Methods for excessive vibration Slide 38 Mitigation Methods for fumes and dust Huge motor driven air blowers installed at the entrance of the caverns to pump in fresh air to the blasting faces and caverns Huge flexible ducts inside the access tunnels which carry air to the blasting faces and caverns Slide 39 Water table Mitigation Methods Loss of containment Piezometers It is important that during the operation phase, the water table is monitored at all times Slide 40 40 Gas LPG Water Column of water acts as a seal and shuts off cavern Mitigation Methods Failure of AG piping Failure of pipeline. LPG starts to leak Slide 41 Mean Sea Level(MSL) Water Curtain Boreholes Water curtain tunnels Storage Caverns Separation of different products to be stored Slide 42 Storage Caverns The caverns for products other than LPG are intertized by filling the vapour spaces with either nitrogen or flue gases. The oxygen content reduced to less than 8%. This will avoid any explosions caused by static electricity Mitigation Methods For fires /explosions Crude oil Nitrogen or flue gas Slide 43 Measures Adopted for Monitoring the SAFETY & DISASTERS in Underground storage caverns We have Miles to go Thank You 43