A Novel Environmentally Friendly, Cost Effective Method for Hydraulic Fracture Geometry Evaluation: Cased Hole Cross-Dipole Data

Abstract

Abstract Cased hole cross-dipole acoustic acquisition is a novel environmentally friendly and cost-effective method for hydraulic fracture geometry evaluation. This method eliminates the environment contamination by the radioactive tracers and replaces the costly micro-seismic monitoring system. Radioactive tracer usage has a risk of pollution associated with improper storage, transportation and use of low dose, short half-life radioactive materials. The new technology eliminates the risk of having radioactive contamination during hydraulic fracturing operations. The sonic anisotropy measurements comparison taken before and after the hydraulic fracturing job allows estimating differential acoustic anisotropy and enables hydraulic fracture geometry evaluation. The method replaces radioactive (R/A) tracers and eliminates any risk of radioactive contamination, high cost, and complex hydraulic fracturing microseismic monitoring (HFM) operation which requires well monitoring. The method was successfully implemented in Greater Birba Cluster in the Sultanate of Oman, during hydraulic fracturing operations in 2020. Results were compared and validated with radioactive tracers, spectral noise log and microseismic monitoring data. This was a first use of sonic anisotropy measurements for fracture geometry evaluation in Petroleum Development Oman (PDO) and the Gulf Cooperation Council (GCC) region. In terms of Zero radiation Risk: The common R/A Tracers Antymoniy-124, Iridium-192 and Scandium-46 have a half-life from 60 to 83 days. One curie of these tracers will give a dose rate of 480 -1090 mR per hour at a meter. Tracers are compounds with both internal and external exposure hazards to humans; they emit highly energetic gamma/beta radiation which can cause localized damage if ingested, inhaled or absorbed by the skin. Externally, both beta and gamma radiation can cause localized damage to exposed areas. Eliminating operations with these materials reduces risk of exposure hazard for field personnel to zero.