(71c) Development and Application of Spacing Chart for Simultaneous Operations (SIMOPs) in Unconventional Shale Gas Fields

There has been a boom in development of North America’s unconventional shale gas in recent years. Due to heavy reliance on equipment-intensive operations such as hydraulic fracturing, and an increasing desire to minimize surface disturbance and footprint, well site equipment spacing and layout is becoming a more complex issue for unconventional gas projects, particularly when there are simultaneous operations (SIMOPs) at the same well pad location. Technical Safety Engineering in Shell Exploration & Production Company developed a spacing chart for SIMOPS to help field supervisors and personnel make decisions about equipment layout for SIMOPs including drilling, completion, flowback, production, and construction.

Development of the chart employed a method using consequence modeling, which studies the physical effects of flammable gas dispersion upon release, and heat radiation from jet fire or pool fire. Release scenarios were identified for SIMOPs equipment from which release and ignition of flammable hydrocarbon may occur. Scenarios and minimum spacing distances were selected according to the principle of Managing Risk in Shell’s [1]HSSE & SP Control Framework. The development process provides an opportunity to check through onsite hydrocarbon release and fire hazards in a systematic way for various well site operations.

The chart is used at Shell’s unconventional shale gas facilities in the United States and is integrated into Shell’s overall risk management system for SIMOPs. The aim is to use the spacing chart as a practical tool to manage the risk of fire hazards at well sites. Engagement with leadership of the various parties responsible for well site operations is necessary for successful chart usage in the field and establishment of a feedback channel for further improvements to the chart. Delivery of the chart to the field also enhances awareness of fire risks through communication and onsite training.