Field-Proven Effectiveness of Self-degrading Diversion Particulates as a Diversion Method in High- and Ultra-Low-Permeability Formations

Abstract

The optimization of stimulation treatments in Mexico has required the use of novel diversion technologies to increase the productivity of wells by improving the coverage of stimulation fluids and reducing completion costs. Self-degrading particulate has become widely used in the country because of the diverter flexibility. Job experiences range from hydraulically fracturing unconventional reservoirs to the matrix acidizing of naturally fractured carbonate formations. The purpose of this paper is to verify the effectiveness of this material for achieving the selective stimulation of multiple intervals, either in horizontal or vertical wells.Because there is no confidence in a complete stimulation of all open intervals, diagnostic techniques have been implemented to determine the effectiveness of diversions. For near-wellbore (NWB) monitoring, technologies such as radioactive tracers and distributed temperature sensing (DTS) have been used to determine treatment fluid locations after the application or in real-time. Downhole microseismic monitoring has been performed for far-field indications of diversion success in hydraulic fractures of vertical wells with multiple intervals open at the same time. This paper discusses four wells from the north, central, and south regions in Mexico. All of them have completely different reservoir properties and completion types.Improved production increase was the main difference between wells where diversion with selfdegrading particulate diverters was used compared to those that were not treated with diverters; a production increase from 30 to 70% was achieved. Completion time was reduced with the implementation of the novel self-degrading particulates vs. other possible methods, allowing faster return of investment (ROI). Real-time decision making could be performed using both a diverter and monitoring techniques to assure a uniform treatment placement. Another differentiator was the simple logistics required to handle the material compared to other additives employed in the past. Because of the performance of the diverter, it has been applied in more reservoirs with extremely variable permeabilities across the country (tight gas and oil sandstones, gas and oil shales, and naturally fractured oil-bearing carbonates).Downhole temperature is the main controlling factor to accelerate or retard the degradation of the particulate, as it must take into account that in cooler formations, longer times are required to achieve complete degradation. Its independence of the wellbore geometry has increased the implementation in openhole and cased-hole completions, despite the final shape of the perforations.

A Validation Assessment of Microseismic Monitoring

“…Diversion is an application where microseismic monitoring is used to determine if fracturing could be forced into regions that perhaps would not otherwise be fracturable because of stress, rock properties, shadowing, entrance conditions, or a number of other possible factors (Waters et al 2009b;Downie et al 2013;Viswanathan et al 2014;Gutierrez et al 2015;Krenger et al 2015;Diakhate et al 2015). Diversion could be applied in both refractured wells and in original stimulations.…”

Experimental study on plugging behavior of degradable fibers and particulates within acid-etched fracture

“…In light of this, temporary plugging and diverting acid fracturing technology was proposed to improve the stimulation effect. In general, this technology can be divided into two types, which are mechanical diversion and chemical diversion (Gutierrez et al, 2015). Traditional mechanical diverters mainly include drillable bridge plug, straddle packers and liners while the chemical diverters include temporary plugging agents (particulates and fibers), foam, viscous fluids, etc.…”