Patent attributes
The present invention relates to a method for controlling a tool string having a downhole self-propelling wireline tool having wheels rotated by means of hydraulics and connected to projectable arm assemblies projected by hydraulics, comprising running a downhole self-propelling wireline tool into a wellbore, the downhole self-propelling wireline tool being connected to a second end of a wireline, and a first end of the wireline being connected to a power supply, the downhole self-propelling wireline tool having a tool body and a plurality of wheels rotated by means of hydraulics, and each wheel being connected to a projectable arm assembly projectable from the tool body by means of hydraulic fluid from a first hydraulic pump, the downhole self-propelling wireline tool having an electric motor rotating at an operational rotational speed for driving the first pump; supplying electric power to the downhole self-propelling wireline tool to operate the downhole self-propelling wireline tool at a first speed to urge the downhole self-propelling wireline tool through the wellbore at a first force; determining a motor output torque of the electric motor; determining a maximum allowable motor rotational speed based on the motor output torque; and comparing the operational rotational speed with the maximum allowable motor rotational speed, wherein the method further comprises adjusting the operational rotational speed of the electric motor based on the comparison in order to adjust the first speed to a second speed if the operational rotational speed is higher than the maximum allowable motor rotational speed. The invention also relates to a hydraulically driven downhole self-propelling wireline tool configured to perform the method.
