Our analysis of the structural features and technological capabilities of serial downhole hydraulic motors (hydraulic machines), designed for drilling wells, has revealed their shortcomings. These include the limited resources due to the complexity of their design, the consumption of a working fluid, significant dimensions in length, mass, low rotation frequencies of the shaft, which do not correspond to the technological modes of wells diamond drilling. Based on the analysis of structural schemes of downhole hydraulic motors it has been concluded that the greatest opportunities for maximum use of the potential energy of a working fluid are demonstrated by rotary-type hydraulic machines.We have proposed, as the object of the study, a structural scheme of the hydraulic machine, which applies the physical principles of converting the weight (energy) of the column of a working fluid at the time of stator rotation around the non-rotating rotor. The principles of separation in the direction of movement of the incoming flow from the reverse spreading have been taken into consideration, as well as the exclusion of a stagnant zone and the creation of a multilevel momentum of reactive forces by the flow of a fluid.Based on the devised procedure, we have performed theoretical calculations of energy characteristics of a two-chamber deep hydraulic machine, defined technical specifications; the calculation scheme of force interaction between a working liquid and the elements of a hydraulic machine is given.Based on the results from theoretical calculations, the structural-technological documentation for a downhole hydraulic machine has been developed; a prototype was made and experiments were conducted to determine operability of the scheme, as well as the boundary values of its operation. The quantitative values for its energy characteristics were determined based on the readings from control-measurement instrumentation.We have conducted a comparative analysis of the technical and energy characteristics of a rotary-type downhole hydraulic machine with industrially produced hydraulic engines, the turbodrill TG-124, and the screw engine D1-124, of the same diameter.Conditions for the utilization of a downhole hydraulic machine have been proposed, as well promising directions for the further research and development to improve it and expand the scope of its application