SPE-214562-MS

 

Degradable Plug Technology Holds Pressure for 32 Hours and Eliminates Risk of Intervention in Tight Gas Reservoirs 

 

 

Abstract

Plug and perf technique is a common method to unlock the potential of tight gas formations. The conventional method is to set millable plugs to establish zonal isolation between target stages. A new degradable frac plug has been introduced for high pressure and high temperature applications in sandstone formations plug and perf hydraulic fracturing operations. The development and deployment of the degradable frac plugs that are capable of holding 32 hours of targeted pressure to optimize the cost and time of the conventional well intervention in tight gas reservoirs in Saudi Arabia is presented in this paper.

In conventional plug and perf stimulation operations each plug is milled out via coiled tubing. This process increases operational risk and cost associated with multiple downhole trips. Another challenge is wellbore accessibility post stimulation operations. Without changing the fracturing design, two degradable plugs in a three-stage well were deployed. Downhole conditions presented significant challenges including high temperatures of 285 F and pressures. By using a degradable plug, post-frac interventions can be eliminated as the entire plug will degrade in downhole conditions. This would allow the well to be brought online faster than a conventional method would allow.

Operational challenges have been experienced during the first deployment of the plug. The plug has successfully held pressure for 32 hours while being exposed to wellbore fluids, which is one of the longest times achieved for a degradable frac plug. One of the main reasons of such success is that the plug is composed of high-grade material. While the plug maintained its integrity for 32 hours in high pressure, it degraded to fine particles post frac operations. Furthermore, the plug was trial tested without affecting the stimulation goals or the overall operation for such well. On this trial test, the plug has shown the ability to eliminate HPCT trips and the associated risks of HPCT intervention. To confirm dissolution of the plugs, an assessment CT run was performed and confirmed shallower plug was not dissolved after 32 hours while the deeper plug already dissolved.

With the spread of plug and perf technology on a global level and the increase of horizontal multistage stimulation methods, it is important to capitalize on fit for purpose technologies versus a one-size fits all approach. To address the challenges associated with longer laterals and increasing stage counts, degradable plug technology can be used to improve well economics and reduce associated risks. The elimination of mechanical intervention is the next breakthrough in efficiency gains to increase laterals and achieve higher stage counts.

https://onepetro.org/SPEMEDT/proceedings/23MEDT/2-23MEDT/D021S010R002/519805