Will your surface microseismic hydraulic fracture monitoring project be successful?
The benefits of microseismic monitoring of hydraulic fracturing are well understood, and continue to grow as acquisition, processing, and interpretation methods improve. Most surveys are conducted using downhole receivers placed close to the reservoir zone. However, for some surveys, a surface monitoring operation can produce good results and provide certain advantages compared to a downhole survey including: • No need for an observation well. • No problems with high reservoir temperatures. • Typically more accurate spatial locations (x,y) of events. • No spatial bias (or distance-to-observation-well bias), which is especially important for large multi-well projects. • Better cost scalability to multi-well projects, and probably lower overall costs for multi-well projects. • More robust source mechanism determination, especially compared to single observation well downhole monitoring. The disadvantages of a surface survey compared to a downhole survey include: • Less precise depth locations of events. • Typically higher costs for a single well project. • Lower sensitivity, and higher risk of failure. The risk of failure, especially in a new area or a new formation, probably deters people from using surface monitoring. Microseismic geophysicists who work for operators describe their discomfort in being unable to answer the question when asked by their management, ‘Will a surface project be successful?’ We present a summary of our experiences with successful and failed projects, we establish a set of metrics for the purposes of comparison, and we provide guidelines for planning successful projects.