Cost Effective Optical Seismic System for Hydraulic Fracture Diagnostics

Hydraulic fracturing of oil and gas reservoirs can be extremely productive but may also be expensive, uncertain, and carry environmental risks. One challenge is the difficulty of mapping fracture networks while they form and as they evolve over the lifetime of the well, preventing a thorough understanding of reservoir dynamics. Major issues include unproductive frac stages, migration of fluids into the environment, and costly interventions for unexpected problems. High quality downhole measurements of seismic signals are proven to help survey reservoirs, study fracture dynamics, and monitor well conditions. However, existing electronic tools appropriate for downhole measurements have high costs and limited survivability in the harsh environments (particularly high temperatures) of modern unconventional wells, with a form factor which is complex to deploy and often incompatible with well configurations where hydraulic fracturing is being used. Our solution is a cost effective, narrow diameter tool string to simplify seismic deployments and reduce cost, encouraging wider adoption in all oil and gas reservoirs. A passive fiber optic sensor allows long- term survival at elevated temperatures (up to 250°C). Observations and surveys can continue long after stimulation, improving long-term models for future operations. Robust tools with high bandwidth and high sensitivity have already been demonstrated in lab and field tests. Phase I demonstrated sensor designs with minimal size, the ability to optimize sensor response, and simplified assembly and testing procedures. It also produced concept designs for a sensor housing allowing reduced cost and simplified deployment compared to existing seismic sensor systems. Phase II includes efforts to fully optimize sensors for ideal response and minimal cost, produce a prototype tool string incorporating important features of a final product, and to test the system at a range of temperatures and pressures. It will culminate in a field test of a small scale array of sensors. Improve subsurface modeling that will reduce the number of failed frac stages and dry wells, Obtain data during and after fracturing, improving real-time decisions to maximize production, Identify environmental or safety concerns early, avoiding hazards to operators and the public, help quantify the total resources in a reservoir and increase the recovered fraction.