Fluid drilling head nozzle design

Abstract

A fluid cutting head of the type having a plurality of nozzles in a rotatable nozzle assembly for cutting a bore hole in rock. The cutting head has nozzles arranged to be supplied with high pressure drilling fluid, forming jets positioned to cut adjacent rock. The nozzles include one or more generally axially facing pilot nozzles, and one or more generally radially facing reaming nozzles. At least the pilot nozzles include a non-tapering outlet section such that the jet issuing therefrom is of substantially constant cross-section in a zone immediately adjacent the outlet section. The pilot nozzles are located in a leading part of the rotatable nozzle assembly, and have a minimized diameter. The reaming nozzles are located in the following part of the rotatable nozzle assembly. The following part of the rotatable nozzle assembly is formed in a step-wise fashion to keep the reaming nozzles close to the rock face.

1 . A fluid cutting head of the type having a plurality of nozzles in a rotatable nozzle assembly for hydraulically cutting a bore hole in rock, said nozzles being arranged to be supplied with high pressure drilling fluid, forming jets positioned to cut adjacent rock, said nozzles including one or more generally axially facing pilot nozzles and one or more generally radially facing reaming nozzles, at least the pilot nozzles including a non-tapering outlet section such that the jet issuing therefrom is of substantially constant cross-section in a zone immediately adjacent the outlet section, and wherein the leading part of the rotatable nozzle assembly incorporating the pilot nozzles is of significantly lesser diameter than the following part of the rotatable nozzle assembly incorporating the reaming nozzles. 
     
     
         2 . A fluid cutting head as claimed in  claim 1 , wherein the reaming nozzles comprise a non-tapering outlet section such that the jet issuing therefrom is of substantially constantly cross-section in a zone immediately adjacent the outlet section. 
     
     
         3 . A fluid cutting head as claimed in  claim 2  wherein the reaming nozzles are oriented such that the jets issuing therefrom are angled rearwardly relative to the direction of travel of the cutting head. 
     
     
         4 . A fluid cutting head as claimed in  claim 1  wherein the following part of the rotatable nozzle assembly is formed in a stepwise fashion of steps of progressively increasing diameters, there being at least one reaming nozzle located in each step such that the jet issuing from each reaming nozzle is located close to the adjacent bore hole surface. 
     
     
         5 . A fluid cutting head as claimed in  claim 1  wherein one or more of the nozzles have an inlet portion of inwardly tapering section upstream of the non-tapering outlet section. 
     
     
         6 . A fluid cutting head as claimed in  claim 1  wherein the pilot nozzles have an internal diameter less than 1.0 mm. 
     
     
         7 . A fluid cutting head as claimed in  claim 1  wherein the reaming nozzles have an internal diameter less than 1.3 mm. 
     
     
         8 . A fluid cutting head as claimed in  claim 7  wherein the reaming nozzles have an internal diameter between 0.5 mm and 1.3 mm. 
     
     
         9 . (canceled) 
     
     
         10 . A fluid cutting head as claimed in  claim 2  wherein the following part of the rotatable nozzle assembly is formed in a stepwise fashion of steps of progressively increasing diameters, there being at least one reaming nozzle located in each step such that the jet issuing from each reaming nozzle is located close to the adjacent bore hole surface. 
     
     
         11 . A fluid cutting head as claimed in  claim 3  wherein the following part of the rotatable nozzle assembly is formed in a stepwise fashion of steps of progressively increasing diameters, there being at least one reaming nozzle located in each step such that the jet issuing from each reaming nozzle is located close to the adjacent bore hole surface. 
     
     
         12 . A fluid cutting head as claimed in  claim 4  wherein the following part of the rotatable nozzle assembly is formed in a stepwise fashion of steps of progressively increasing diameters, there being at least one reaming nozzle located in each step such that the jet issuing from each reaming nozzle is located close to the adjacent bore hole surface. 
     
     
         13 . A fluid cutting head as claimed in  claim 2  wherein one or more of the nozzles have an inlet portion of inwardly tapering section upstream of the non-tapering outlet section. 
     
     
         14 . A fluid cutting head as claimed in  claim 3  wherein one or more of the nozzles have an inlet portion of inwardly tapering section upstream of the non-tapering outlet section. 
     
     
         15 . A fluid cutting head as claimed in  claim 4  wherein one or more of the nozzles have an inlet portion of inwardly tapering section upstream of the non-tapering outlet section. 
     
     
         16 . A fluid cutting head as claimed in  claim 10  wherein one or more of the nozzles have an inlet portion of inwardly tapering section upstream of the non-tapering outlet section. 
     
     
         17 . A fluid cutting head as claimed in  claim 11  wherein one or more of the nozzles have an inlet portion of inwardly tapering section upstream of the non-tapering outlet section. 
     
     
         18 . A fluid cutting head as claimed in  claim 12  wherein one or more of the nozzles have an inlet portion of inwardly tapering section upstream of the non-tapering outlet section. 
     
     
         19 . A fluid cutting head as claimed in  claim 2  wherein the pilot nozzles have an internal diameter less than 1.0 mm. 
     
     
         20 . A fluid cutting head as claimed in  claim 3  wherein the pilot nozzles have an internal diameter less than 1.0 mm. 
     
     
         21 . A fluid cutting head as claimed in  claim 4  wherein the pilot nozzles have an internal diameter less than 1.0 mm.