Enhancing Production From Low-Permeable Reservoirs With Advanced Hydraulic Fracturing Monitoring Techniques

Abstract

Abstract Hydraulic fracturing is an important technology that can improve the production of oil and gas from low-permeable reservoirs, but it can also be challenging and requires ongoing monitoring and assessment to ensure that the fractures are performing as expected. The height of the fracture can significantly affect the efficiency of production. Spectral noise logging and tracer analysis are two methods that can be used to determine the height of the fracture and assess its performance. The Tracer analysis technique involves mixing a tracer material with the hydraulic fluid used during the fracturing process. The subsequent monitoring of the radioactivity level versus depth provides information about the fractures' placement and extent along the wellbore. On the other hand, a passive spectral acoustics survey will record the acoustic signal that is generated by the flow through the fractures during production, thus enabling the exact determination of the fractures' position and their active heights along the wellbore axis. By combining these techniques with temperature and hydrodynamic modelling, it is possible to calculate the specific performance of each fracture.The results from three wells' surveys confirmed the effectiveness of this methodology. Both Tracer and Passive spectral acoustic methods were able to determine the location of the fractures along the wellbore axis. However, the spectral noise determination is a lot more informative due to the nature of the measurement, which responds properly to the contributing or active height of each fracture whilst the GR response opposite the Tracer represents the physical extent of the fracture along the wellbore. One more point; the Tracer fluid can migrate away from the fractures due to poor cement bonding, etc. which could confuse the interpretation by falsely indicating a fracture extent at a certain depth.In addition to the findings described above, this methodology allows the pinpointing of the fracture depths behind the casing, away from the fracturing ports. The coupling of these measurements with a High Precision Temperature sensor and with Temperature Modelling allows the determination and quantification of the flow rates inside and outside the wellbore, thus providing a full and comprehensive picture of the downhole flow profile.