Pressure testing: Wireline Lubricators, BOPs, Pressure Vessels, Storage Vessels, Storage Tanks, Pipelines, Valves, to ensure integrity before placing in service
Purging: Wireline Lubricators, BOPs, Pressure Vessels, Pipelines, Valves, Storage Vessels, Storage Tanks to remove hydrocarbon or other hazardous gas and liquids before disassembly, removal and/or placing in service
Displacing/Displacement: Wireline Lubricators, BOPs, Pressure Vessels, Storage Vessels, Storage Tanks, Pipelines, Valves, is to replace hydrocarbon or other hazardous gas and liquids before disassembly, removal or placing in service and/or introducing another product which may not be compatible.
Placing Nitrogen Blanket is a method used to prevent Hydrocarbon gas (Sweet or Sour) from being released while performing service work such as snubbing and wireline operations. This is used for other hazardous gases as well. The nitrogen holds back or restrains the hazardous product from being released. If there happens to be a leak then it is with a non-harmful product versus flammable / hazardous product.
Commissioning of new wells: this is the practice of purging all the air/oxygen out of the pressure vessels and pipelines prior to placing the well into production. After the completion of a well, production facilities are put in place and through the construction phase air / oxygen is trapped in the vessels and pipelines. These facilities are also pressure tested at this time to find and repair any leaks. It is also feasible to ensure equipment is working properly with an inert gas before placing in service in the event that some of the equipment may not be working properly and need adjustment or replacement. Performing this test at this time eliminates the potential hazards of having to remove / replace equipment containing flammable gases or liquids.
Facility maintenance: Whenever production facilities need maintenance it is recommended to purge the pipelines, valves and pressure vessels to remove hazardous / flammable product before disassembly to prevent fire, explosions and injury to workers. After re-assembly it is important to purge the air out of the system before introducing flammable products and pressure testing to ensure integrity of equipment.
Snubbing: Prior to starting snubbing operations it is recommended to pressure test BOPs, lines and other working components to eliminate the possibility of leaks. During the snubbing operations the flow of nitrogen can be set at 700-1000kPa higher than wellbore pressure using the regulator to keep wellbore fluids from escaping while staging. This prevents hydrates from developing in the BOPs and surface lines and also prevents release of any flammable gas or liquids from the well.
Wireline Operations: Purging and Pressure testing lubricator with nitrogen is a crucial step which should not be overlooked. While installing the lubricator air / oxygen are trapped in the lubricator and if the well is opened introducing gas a volatile mixture is created that could cause an explosion or fire resulting in injury or equipment damage. It is proper procedure to equalize the lubricator before opening the master valves to prevent surging and washing out of the valves. Pressuring up on the lubricator to equalize will also help to avoid hydrates from forming. When performing static gradients and production logging it is important wellbore conditions are kept stable and equalizing with nitrogen will prevent the surge effect that happens when the well is opened.