Deviation control in a vertical well (or the vertical portion of a directional well) can be challenging, especially when pushing the limits for maximum penetration rate. Over the years rotary steerable systems (RSS) have been adapted to fit the vertical drilling market. These electro-mechanical directional control systems are set-up to seek low-side but they come at a relatively high cost of RSS. This paper describes a purpose-built 100% mechanical vertical drilling system. The vertical drilling system has been developed to drill vertical wells economically with the accuracy and borehole quality of a rotary steerable system. The intelligent mechanical control system has been instrumented to analyze response in different drilling environments throughout North America land. Compact measurement sensors embedded into key components of the tool record system behavior and response. Through case studies, the effectiveness of the mechanical control system to eliminate deviation on vertical wells will be demonstrated. Onboard memory data from the sensors will be used to examine the stability of the system and prove that simple mechanical control is an efficient and effective method for vertical drilling.

Maintaining steady weight on bit (WOB) while drilling can be difficult at depth due to drill string flexibility, wellbore friction and downhole dynamics. Variable slack-off weights and drill string buckling results in un-steady WOB that generates string- and bit-induced stick-slip and torsional vibration. Variable string rotation speed in revolutions per minute (RPM) and differential mud motor pressure causes changes in length of the drill string. These changes in length are directly acting on the drill bit and can result is a very chaotic drilling situation that is extracting energy from the drilling process. This paper describes the operation and field-test results from a new tool designed to maintain steady WOB. The constant weight on bit tool was instrumented with sensors to gather critical information on inclination, sliding toolface, vibration, string rotating speed and erratic RPM events. The data gathered is presented to show downhole drilling dynamics improvements with the steady WOB tool incorporated into the bottom-hole assembly (BHA).

Weight transfer problems, hanging-up, poor toolface control and diminishing ROP are all problems that are encountered with steerable motors in high angle and horizontal wells. A number of oscillation devices have been introduced to the market over the years to aid these common problems. Both axial and lateral vibration tools have proven to provide improvements to drilling performance and toolface control. However, as with any device, there are always limiting factors, and oscillation devices could cause unwanted vibrations that interfere with measurement-while-drilling (MWD) systems and even cause component failures. This paper describes the operation and field-test results from a new axial oscillation tool. The tool uses a mud valve to generate pressure pulses in the string. These pressure pulses are magnified using a specifically designed stroke tool referred to as an amplifier. The mud valve is driven with a short power section from a Positive Displacement Motor (PDM). The lobe configuration of the power section is directly related to the frequency of the tool, while nozzles in the tool allow for variable pressure regimes of differing applications. The system was tested with specific MWD systems in a flow loop prior to the job to confirm compatibility. Key components in the string were instrumented to gather critical information on vibration frequency levels throughout the BHA in an effort to optimize system performance. A compact, self-contained 3-axis inclinometers and 3-axis shock sensors (¾-in diameter and 3.8-in length) have been deployed during field testing to capture downhole dynamics. These sensors were strategically positioned in the BHA to gain understanding of vibration propagation distance/pattern and vibration frequency changes over the course of the run. Downhole instrumented sensors were used to confirm the value of the axial vibration mechanism. The use of multiple compact downhole dynamics recording devices has provided new insights in challenging steerable motor drilling applications, assisted with an axial friction reduction tool.

Drilling turbines, commonly referred to as Turbodrills, have historically been used for hard-rock applications in conjunction with diamond impregnated drill bits. Their use in North America land was typically restricted by rig stand-pipe-pressure limitations. Now, the latest generation rigs in North America land have sufficient stand pipe pressure to make use of Turbodrills. Reducing the bit speed of a Turbodrill can provide significant advantages. Reducing the bit speed and increasing torque makes the Turbodrill suitable for a wider range of drilling environments, including high-temperature wells. Turbodrills require no elastomer re-lines like Positive Displacement Motor (PDM) Power Sections, which are typically re-lined after every run in oil based mud. High-performance PDMs generate significant vibration which could reduce the life of measurement-while-drilling (MWD) systems. On the other hand, Turbodrills produce very little vibration, hence the life expectancy of bottom-hole assembly (BHA) components can be increased. Drilling with less vibration will lead to a more efficient drilling system and reduced non-productive time (NPT). This paper describes the operation, flow test and field test results from a new Gear-Reduced Drilling Turbine (GRDT). Key component in the GRDT were instrumented to gather critical information on vibration, shock, temperature and rotation speed in revolutions per minute (RPM).

Pad drilling has become commonplace for North America shale development drilling, which requires tighter well spacing/separation and reduced anti-collision risk. A new digitally-controlled rotary-steerable system (RSS), extensively embedded with electronics, solid-state sensors and electrically controlled mud valve, has been developed specifically for drilling vertical and nudge well profiles from pads in North America. Unique technology includes a slow-rotating steering housing with four mud activated pads to apply side force at the bit. The pad activation is controlled using a novel mud valve driven by a low-power electric motor and gearing system. Activation of the steering pads and control of force to the steering pads is achieved using a small percentage of mud flow and approximately 500 psi pressure drop below the tool. The limited amount of mud flow passing through the mud valve eliminates internal wash issues and reduces repair costs. The electronics measurement and control system are mounted in the slow-rotating steering housing and includes 3-axis inclinometers, 3-axis magnetometers, 3-axis shock sensors, 3-axis gyros, and temperature sensors. Additionally, compact drilling dynamics sensors are placed at the bit box to gather at-bit data to evaluate bit-rock dynamic interaction. This paper will describe the unique features that allow the system to be reliable and cost-effective for high-volume land drilling activities. The RSS bottom-hole assemblies (BHAs) have been extensively instrumented with multiple downhole dynamics sensors, which reveal a challenging drilling environment unique to vertical drilling and nudge applications and show the performance of the RSS in this environment.