INTRODUCTION:
It is a known fact that gas is a highly flammable material found in nature. Slight negligence in its handling, storage and use may result in Gas Explosions which can cause tremendous damage.
What is a Gas Explosion: Gas Explosion is a process in which combustion of a pre-mixed gas-air cloud causes a rapid increase of pressure. This process may occur inside Gas Well equipment or pipes, in a Gas Well facility or in open areas.
This process can be best described as chain of activities in the following order.
Release of gas/liquid results either in: a) No Ignition
b) Immediate Ignition that can cause a fire
c) Formation of combustible fuel-air cloud which on ignition results in Gas Explosion that leads to perspective damages to either personnel or property depending upon the surroundings.
Causes of Gas Well Explosions
There are several reasons for causing Gas Well Explosions.
Improper handling of material: Several cases of Gas Well Explosion incidents have been reported worldwide due to negligence by workers in the field in either operating the equipment or not properly following operational regulations strictly.
Recently in Dallas/Fort Worth investigation reveals that a backhoe operated by a third party contractor working in the area accidentally struck the gas pipeline while digging for another line causing a Gas Well Explosion.
Another incident of Gas Well Explosion happened at Chuandongbei gas field in Gao Qiao town in China causing in release of H2S gas. Again it is thought to be caused by a puncture to the highly pressurized gas well caused by drilling. The puncture caused initial leakage resulting in Gas Well Explosion later on. Overall 9,000 people were poisoned of which 243 people died and several others remain in critical condition.
Prevention in Gas Well Explosions
Gas Well Explosion is defined as a process in which uncontrolled flow of gas, oil or their fluids are escaped from a well bore into the atmosphere. To prevent it from spreading ignition of well can control the process by converting escaping H2S gas to sulphur dioxide which disperses more effectively.
Following factors can be taken into account in order to prevent Gas Well Explosions.
The first basic step in reducing the impacts of potential hazard is to keep people and population at safe distance so that if accidents do occur the distance will take its course in diminishing the effects of the accident.
Well Testing: Pressure Measurement at regular productive interval is used as basis for well testing analysis and is primarily used for determining rock properties and producing formation limits.
Proper Training of Gas Well Workers: To prevent Gas Well Explosion efficient time should be allowed in drilling mud to circulate to control the pressure. In order to achieve this target, workers should be properly informed and trained for operating machineries and other equipment when on premises where accidents are prone to happen.
Recently in Oklahoma, four people were injured when an explosion occurred in Gas Well while performing pressure test because one of the workers forgot to hit the shut-off valve before unscrewing the plug.
Furthermore to prevent any future accident several types of analyses can be performed such as:
Ventilation study including Wind Chill Index analysis
Dispersion analysis
Worst case explosion analysis
Probabilistic explosion analysis
Blast propagation
Escalation potential
Mitigation including layout & design optimization
Gas detector optimization
Explosion response analysis
To perform these analysis two major requirements need to be fulfilled
i) Geometric design of plant must be represented in sufficient detail, consisting of piping sizes 2-3cm in diameter.
ii) Cloud sizes must be considerably realistic in Explosion analyses based on dispersion analyses.
To find more details of these analyses go to www.gexcon.com.
Injuries Resulting from Gas Well Explosions
Burn Injuries are very common in Gas Well Explosions varying from minor burns to extreme injuries resulting in disfigurement and scars. Some extreme injuries may require hospitalization and can become very costly. Based on their severity burns can be classified as:
First Degree burn injuries as minor burns in which only top layer of skin is damaged.
Second Degree burn injuries go beyond top layer and skin can become blistery, swollen and oozing.
Third degree burn injuries cause damage to all layers of skin which ends up destroying the nerves and blood vessels in the skin. This form of burn is very severe and may require constant reconstructive surgeries, skin grafting resulting in scars and permanent disfigurement.
Some law firms specialize in dealing with cases of burn injuries in order to compensate for any physical or economical loss resulting from Gas Well Explosions.
OSHA Requirements for Determination of Hazardous Materials:
OSHA has issued Draft Guidance for Hazardous Determination.
For Compliance with the OSHA Hazard Communication Standard (29CFR 10.1200)
This purpose of this document is to help manufacturers and importers identify chemicals as chemical hazards so that that the employees and other potential users are well informed about these hazards as required by OSHA standards.
Fire Hazards
Fire hazards: Flashpoint is of critical importance when taking into consideration liquid chemical’s propensity to burn. Flashpoint is the lowest temperature at which a chemical will provide ignitable vapors which if comes in contact with air may cause fire. OSHA Fire safety Standard addresses general industry standards for fire safety and emergency Evacuation (CFR, Subpart E, 1910.36, 37 and 38).
OSHA Requirements for proper Evacuation Techniques
In order to meet OSHA standards an emergency action plan (EAP) is required. EAP is a written document designed to guide employers and employees techniques for workplace emergencies.
Some of the basic steps involved in emergency action plan (EAP) are:
Evacuation methods and emergency exit route procedures
Maintaining critical plant operations by employers before their evacuation
Follow-up procedures after the evacuation
Medical duties required
Reporting of fires or explosions
List of persons to be contacted for further information regarding the plan
