the flow 51 to an accumulator 100 the accumulator 100 may include for example a first chamber in communication with the flow 51 that is separated from a second chamber containing a hydraulic control fluid by a piston for example thus the accumulation of pressure from the flow 51 establishes a control pressure in a hydraulic output line 101 of the accumulator 100 in some embodiments of the invention the hydraulic output line 101 may be connected through a check valve 107 to a pressurized source 120 thus the accumulator 100 may serve to pressurize a particular source 120 for purposes of forming a direct hydraulic power source a hydraulic control circuit 102 is in communication with the pressurized source 120 for purposes of controlling when this pressurized source is applied to one or more downhole tools via hydraulic output lines 108 other variations are possible and are within the scope of the appended claims referring to fig5 in some embodiments the hydraulic control also includes a maximum pressure relief valve 110 that provides an upper limit on the pressurized source in some embodiments of the invention the hydraulic system 18 may be a closed system in that the maximum pressure relief valve 110 is connected to a chamber to effectively u201c store u201d a maximum pressure in the well this chamber may be used to power one or more downhole tools for example thus referring to fig6 in some embodiments of the invention a technique 200 may be used for purposes of performing a particular downhole function pursuant to the technique 200 a flow of well fluid is directly converted into hydraulic pressure as depicted in block 202 the hydraulic pressure is then used block 204.