High Pressure Fluids For Extended Jetting And Drilling During Eor And Stimulation Methods Within Geothermal Reservoirs

Abstract

A more widespread use of geothermal energy is still dependent on more adequate, economic, made for purpose exploration, drilling and completion technologies that will reduce challenges and risks of tapping into deeper geothermal reservoirs. Some of today’s technical and with that economical limitations are due to mere mechanical means of rock breaking, trying to overcome rock´s compressive strength and thus, resulting in low rate of penetration (ROP) and high bit wear. Therefore, techniques are being sought out in order to drill and develop deep geothermal and other resources and minerals more efficient and successful. The utilization of intensified fluids for micro jet drilling up to percussion may help to improve this situation. In order to serve as a serious, economic and safe well enhancement alternative in conventional exploration drilling and mining work, high pressure jetting techniques are experimentally investigated at GZB in order to gain fundamental knowledge about fluid-rock interaction and the rock failing process. The governing rock removal and drilling parameters have been investigated and analyzed. This includes work and experiments under surface as well as pressure-controlled, downhole conditions. All pertinent process parameters like pressures, flow, speeds, extracted rock volume etc have been metered. The results have been linked and compared to rock properties like density, porosity, permeability, etc. Additionally, such a new jet drilling type process needs to be monitored and controlled via a new online sensing system, currently being under development at GZB for such low to no contact drilling methods. High pressure water jet technologies have long been part of the O&G drilling industry quite successfully for workover and EOR. That´s why intensified fluids at higher energy levels are being investigated and put to use for micro drilling in multiple ways to increase production out of reservoirs possessing poor flow and hydraulic conditions. Especially in deep, geothermal applications horizontal jetting and drilling may economically connect existing, vertical wellbores to the reservoir. This technique is gradually under transformation from O&G applications to geothermal environments in harder and deeper rock formations. However, despite being confronted with certain limitations like lateral length, hole size, steerability, QA & QC, this type of stimulation techniques have shown to be able to increase production out of existing and new wells. And further improvements are under way for these techniques. Drilling into hard rock is especially slow, and the pertinent tooling has a rather short lifetime. New tools incorporating hydraulic (DTH) hammer drilling as a medium pressure technique with percussion does greatly improve this situation as drilling velocity (ROP) is being well increased. Micro DTH hammer drilling may bridge the gap as a stimulation and drilling method into hard rock reservoirs and / or horizontal drilling for the immediate future in both geothermal as well as O&G reservoirs.

AAPG Datapages/Search and Discovery Article #90346 ©2019 AAPG European Region, 3rd Hydrocarbon Geothermal Cross Over Technology Workshop, Geneva, Switzerland, April 9-10, 2019