A system for automatic control of a rotary drill comprises a unit for computing the value of drilling tool penetration per single revolution, said unit connected with its inputs to respective transducers and with its output--to an element for comparison of the current value of drilling tool penetration per single revolution thereof with the preset value of such penetration. The preset value of drilling tool penetration is computed by computer means connected with its inputs to respective transducers and to setters of input parameters. With its outputs, the computer means is connected to the element for comparison of the current value of drilling tool penetration per single revolution thereof with the preset value of such penetration, to regulators of drilling tool axial load and rotation frequency and to an element for comparison of the current value of specific drillability of the rock being drilled with the preset value of specific drillability. The system ensures the possibility of automatic or remote control of the drilling process on the basis of information generated on-line in the course of the drilling operation. The system is capable of operation without re-adjustment, in any field, using a drilling tool of pre-selected type. The system operation ensures the minimum energy consumption and cost of drilling at a high efficiency and drilling tool reliability.

Method or system for developing a surface drilling log indicative of one or more parameters of the formation being drilled. Measurements include the bit revolutions, the depth of the bit in the hole, the weight on the bit, and a determination of tooth dullness of the bit. The results are correlated to produce a parameter in accordance with a predetermined relationship of the measurements and the determination.

A drilling torque and drag monitoring method for a drillstring in a well bore including the steps of measuring hook load and axial displacement of the drillstring, measuring surface torque and angular position of the drillstring, correlating the hook load with the axial displacement of the drillstring so as to produce a first graphical relationship, correlating the surface torque and the angular position measurements of the drillstring so as to produce a second graphical relationship, and comparing the first and second graphical relationships so as to determine a contact resistance between the drillstring and the well bore. These relationships can be used independently or jointly so as to determine the condition of contact resistance. The method includes the step of identifying a slope discontinuity along the graphical curve. This slope discontinuity is indicative of a contact resistance. When the slope discontinuity is a curved segment, then the curvature of the curved segment is computed so as to be representative of a magnitude of a distributed contact resistance along the area of contact between the drillstring and the well bore. An instantaneous axial or rotational compliance can be determined at a point along the slope of the graphical representations. The depth of the area of contact can be computed based upon the instantaneous axial or rotational compliance relative to a given surface axial location or a given surface torque applied to the drillstring.

In a drilling rig of drill depth conventional structure, parameters of interest (e.g. rate of penetration and drill bit location, number of stands, monkey board position) are calculated and displayed by a unified electronic system. A weight transducer measures the load of the drill string on the rig. A movement sensor provides information on movement of the hook. An internal clock provides time signals. The relevant parameters are calculated using a microprocessor from these three factors.

An oilfield monitor and recorder system providing marker positioning using a leadscrew, a stepper motor, a position sensor, driver and control. The control provides zero, span, slew and range functions. The rate input scaling provides calibration, percent, sum to monitor and sum to recorder controls. The pressure input scaling provides zero, span and calibration controls, therefore the input signals are calibrated and scaled for presentation to display and marker control circuits. Record advancement uses tractor drives, stepper motor, precision time base, driver and control in order to provide an accurate time record relationship. This portable battery powered system and apparatus is housed in a briefcase size enclosure. The electrical signals obtained from a plurality of physical conditions are processed, recorded and displayed on respective recorder and display channels, which particularly meets the oilfield stimulation service industry requirements for a portable monitoring and recording apparatus.