Method of developing and producing deep geothermal reservoirs

Abstract

A method of drilling, completing and producing a deep geothermal reservoir to allow the economical extraction of thermal energy from geologic strata, which may be termed as Hot Dry Rock (HDR).

1 . A method of extracting thermal energy from a rock formation, the method comprising the steps of:
 drilling a plurality of wells to a depth sufficient to allow development of at least one fracture joint cloud reservoir;   hydraulically fracturing at least one of the plurality of wells;   dilating the at least one fracture joint cloud reservoir;   forcing cooled water under high pressure and volume into at least one of the plurality of wells to charge the reservoir;   alternately opening and closing a plurality of discharge control valves and a plurality of injection control valves to provide continuous flow from the plurality of wells and permit discharge from the reservoir;   removing heated water from the wells; and   passing the heated water to a heat exchanger.   
     
     
         2 . The method of  claim 1 , wherein the step of drilling includes the step of hydraulic drilling. 
     
     
         3 . The method of  claim 2 , wherein the step of hydraulic drilling includes particle jet drilling. 
     
     
         4 . The method of  claim 1 , wherein a volume of the at least one fracture joint cloud reservoir is increased through simultaneous mechanical and thermal cycling. 
     
     
         5 . The method of  claim 1 , wherein heat values in the at least one fracture joint cloud reservoir are maintained through mechanical and thermal cycling of the reservoir rock. 
     
     
         6 . The method of  claim 5 , wherein the volume of heat that may be swept in the at least one fracture joint cloud reservoir is increased through thermal and mechanically cycling reservoir rock. 
     
     
         7 . The method of  claim 1 , wherein the step of charging and discharging of the system is further includes the step of timing the charging and discharging to produce a sequence of cycles with steady state load following production cycles generated while still inducing coincidental thermal mechanical cycling that results in brecciation and spallation of the reservoir rock. 
     
     
         8 . The method of  claim 7 , wherein the method of heat production is further facilitated by utilizing at least two wells wherein an injection well injects periodically at different injection rates so that the rate is greater than the continuous production rate produced from the production well such that the reservoirs alternately expanded and then allowed to contract in order to generate the combined thermal and mechanical stresses necessary to generate in situ reservoir brecciation while the reservoir is being produced at a continuous rate. 
     
     
         9 . The method of  claim 7 , wherein the method is further facilitated by utilizing at least three wells. 
     
     
         10 . A method of completing geothermal production wells including the steps of:
 drilling a plurality of wells from at least one wellhead through a plurality of earthen formations;   utilizing a first type of drill bit through first upper earthen formations for the generation of the well bore;   utilizing a particle jet drilling bit for bore hole creation within a hot dry rock region disposed beneath the first earthen region;   terminating a first plurality of bore holes in a first Precambrian formation to a depth of sufficient temperature to allow the development of one or more discreet formation fracture joint clouds which are oriented vertically or horizontally as determined by the rock formation;   terminating a second of the plurality of bore holes into a lower region for creating a lower fracture joint cloud generally horizontally disposed beneath the first cloud; and   hydraulically fracturing each cloud to produce a reservoir volume of dilated joints in the formation by pumping at pressures in excess of the joint dilation pressure and the formation break down pressure.   
     
     
         11 . The method as set forth in  claim 10  and further including terminating a third bore hold beneath the regions of termination of the first and second bore holes. 
     
     
         12 . The method as set forth in  claim 10 , wherein the step of fracturing includes imparting a pressurization cycle to charge the reservoir followed by the depressurization of the reservoir to flush the heated water from the dilated joints that produce the heat absorbed by the water during the pressurization and depressurization cycle. 
     
     
         13 . The method as set forth in  claim 12  and further including repeating the process of charging and depressurizing each cloud to develop an aggregate of a plurality of discreet reservoirs that will accept pressurized water to charge the reservoir during dilating the joints allowing the water to travel into the reservoir to be heated and then expelled from the reservoir when the heated water pressure is lowered in the well bore from a wellhead. 
     
     
         14 . The method of  claim 13  including the step of continuously producing heated water by timing the pressure cycling of the well bore to provide one well being injected into at twice the rate the well is reversed flowed. 
     
     
         15 . The method of  claim 14  and further including routing cooled well bore fluid back down the well bore through a control valve to an injection pump. 
     
     
         16 . The method of  claim 14  and further including discharging cooled well bore fluid from the heat exchanger to a surface reservoir pit. 
     
     
         17 . The method of  claim 1 , wherein the step of fracturing comprises the step of dilating a plurality of material joints in the formation. 
     
     
         18 . The method of  claim 1 , wherein the step of drilling includes drilling an upper well portion with a rotary mechanical drill bit. 
     
     
         19 . The method of  claim 18 , wherein the rotary-mechanical drill bit comprises PJARMD methodology. 
     
     
         20 . A method of drilling deep well bores from a wellhead into Precambrian and Hadean Era crystalline rock formations for accessing thermal energy therein comprising the steps of:
 establishing a bore hole drilling system from the wellhead with at least a first and a second type of drilling methodology, the first methodology including rotary-mechanical drilling and a second methodology including hydraulic drilling;   drilling a first bore hole section from the wellhead and into a first formation utilizing the first methodology of the rotary-mechanical drilling;   drilling a second bore hole section beneath the first bore hole section into the crystalline rock formation with the second drilling methodology of hydraulic drilling; and   exposing the thermal energy within the crystalline rock for the access thereto.