Monitoring the Snøhvit gas field using seabed gravimetry and subsidence

Summary Gravimetry and subsidence surveys are regularly conducted to monitor the gas-producing Snohvit field. This technology provides insight into reservoir dynamics with lower costs and shorter turn-around time than widespread 4D seismic. Through two decades, improvements in survey procedures and instrumentation have led to significantly better sensitivity to both gravity changes and subsidence. This has resulted in turn into improved sensitivity to mass changes and compaction throughout the reservoir. In this abstract, we analyze the evolution of the noise level in the three surveys at Snohvit in 2007, 2011 and 2019. We present in detail the results for the 2011–2019 time-lapse, and we describe how these measurements are incorporated into the history-matching routines and used to reduce the uncertainty in key reservoir parameters.