Rotary Steerable System Drilling Technology

Introduction to Rotary Steerable System Drilling Technology

Main Content

1. Overview of Rotary Steerable Drilling Technology

2. Classification of Downhole Rotary Steerable Drilling Systems

3. Typical Rotary Steerable Drilling Systems

   (1) AutoTrak RCLS System: Baker Hughes

   (2) PowerDrive SRD System: Schlumberger

   (3) Geo-Pilot System: Halliburton

1. Overview of Rotary Steerable Drilling Technology

(1) Key Technology: Downhole Rotary Steering

The core is the downhole rotary steerable drilling tool system.

The drill string can accurately increase, stabilize, decrease inclination, and change direction during rotary drilling.

(2) Technical Advantages

The downhole tool operates continuously in a rotating state, leading to better hole cleaning efficiency, higher trajectory control accuracy, and enhanced displacement extension capability.

(3) Application Scope

Widely used in deep wells, high-angle wells, extended-reach wells, horizontal wells, branch wells, and cases where sticking is likely, which are difficult for mud motor sliding drilling.

The closed-loop rotary steerable system (RSS) can automatically adjust the tool's directional performance without tripping out.

It improves drilling efficiency and provides flexibility in trajectory control.

2. Classification of Rotary Steerable Directional Drilling Systems

(1) Classification by Steering Mode

● Push-the-Bit: Applies lateral force directly to the drill bit near the bit.

● Point-the-Bit: The drill string near the bit bends to point the bit in the desired drilling direction.

(2) Classification by the Working Mode of Bias Units

● Static Bias: The bias steering mechanism does not rotate with the drill string during drilling, providing lateral force in a fixed direction.

● Modulated: The bias steering mechanism rotates with the drill string during efficiently drilling, and the control system directs it to provide steering force in a specific location.

The working principle of the rotary steerable drilling system relies on bias units to create directional force by offsetting the drill bit or drill string.

(3) Comprehensive Classification of Steering and Bias Modes

● Static Bias Push-the-Bit: AutoTrak RCLS by Baker Hughes Inteq.

● Dynamic Bias Push-the-Bit (Modulated): PowerDrive SRD by Schlumberger Anadrill.

● Static Bias Point-the-Bit: Geo-Pilot System by Halliburton Sperry-sun.

3. Typical Rotary Steerable Drilling Systems

(1) AutoTrak RCLS System: Baker Hughes

(2) PowerDrive SRD System: Schlumberger

(3) Geo-Pilot System: Halliburton

(1) AutoTrak RCLS System

● Overview

• In 1993, AGIP from Italy and Baker Hughes INTEQ from the USA collaborated to develop this system based on early vertical drilling systems (VDS) and straight well drilling devices (SDD).

• Officially launched in 1997.

• Used for drilling a variety of well types.

● Core Tools

• Non-rotating adjustable stabilizer sleeve: Includes near-bit inclination sensors, electronic control components, hydraulic control valve, and piston.

Non-Rotating Steerable Stabilizer

AutoTrak RCLS System

• Steering Principle: By applying different pressures to the three stabilizer blocks through hydraulic pistons, the combined force causes the drill bit to deviate in a specific direction, creating a lateral force that ensures the bit drills in the desired direction.

Steering Principle: Static Side Force, Dynamic Control

AutoTrak RCLS System

• Overall Design:

1. The non-rotating sleeve has an adjustable steering rib that allows independent operations, creating a lateral force on the drill bit to build or maintain a wellbore trajectory.

2. The downhole computer and sensors continuously monitor and control the current wellbore trajectory relative to the next target, maintaining real-time communication between the surface and subsurface.

   
   

   
   

Control Principle: Two-Way Communication

• Automated steering of the downhole tool while drilling ahead.

• Bypass valve at the stand pipe creates coded flow rate variations of ±15%.

• Commands for steering and controlling MWD/LWD operations.

Surface Equipment

AutoTrak Bit Development

Application Areas

• Directional/Geosteering wells in 8.1/2” - 12.1/4” hole size.

• Where the operator wants:

• Better hole cleaning, less circulation time, fewer wiper trips.

• Extended run lengths by using PDC bits.

• Better hole quality for logging and completion.

• Superior geometrical steering and geosteering to maximize production.

• Extended reach & extended horizontal sections to maximize production, reducing the number of wells and platforms required.

• Achieving high ROP and fewer BHA’s.

（2）PowerDrive SRD System

• Overview:

• In 1994, Camco (UK) developed the rotary steerable drilling (SDR) system, successfully tested at the Montrose area well in the UK.

• In May 1999, Camco merged with Schlumberger's Anadill to register the SR system as PowerDrive.

• In 2000, PowerDrive was upgraded to PowerDrive Xtra.

PowerDrive System

PowerDrive Advantages:

PowerDrive Working Principle:

• Side force is applied by stabilizers extending from the body of the rotating assembly.

• The wellbore path is determined by three contact points.

Problems with Sliding Drilling:

• Unstable direction control.

• Less than optimal Rate of Penetration (ROP).

• Poor hole cleaning.

• Inability to slide.

• Differential sticking.

• Drill string bending.

• High dogleg severity.

• Formation affecting wellbore inclination.

PowerDrive Improving Mechanical Drilling Speed:

• Optimized bit cutting structure.

• Optimized well parameters.

• Continuous bit rotation.

• No reduction in mechanical drilling speed due to sliding.

• Better hole cleaning.

• Fewer doglegs.

• Overall improvement in mechanical drilling speed.

PowerDrive System:

PowerDrive Steering Mechanism:

• The steering mechanism uses hydraulic pressure to extend three stabilizer pads.

• The steering mechanism applies side force to the drill bit, rotating together with it.

Steering Mechanism Pads:

• 
  

• Pad extended.

• 
  

• Pad retracted.

Steering Mechanism Coordination:

Control Range:

• 81 control positions, real-time decisions.

• Each position has two control factors: toolface and dogleg severity.

• [0°, 100% = maximum setting; 180°, 50% = half setting].

PowerDrive Tool Combinations:

PowerDrive Structure and Operating Parameters:

• Length: 16 ft [4.9 m]

• Flow rate: 500 – 1000 gpm [1900 – 3800 lpm]

• Rotation speed: 40 – 220 rpm

• Tool pressure drop: Less than 100 psi [6 bar]

• Minimum pressure drop at bit: 500 psi [34 bar]

• Maximum operating temperature: 250°F [120°C]

• Mud weight: 7.5 – 20 ppg [0.9 – 2.4 sg]

• LCM: Follow MWD instructions

PowerDrive Advantages:

• Integrated tools – simple, no extra equipment or costs required on the platform

• Low tool pressure drop (<100 psi)

• Real-time MWD, LWD, APWD

• Excellent MWD – high-speed transmission (6 bps), ideal for fast drilling

• Data is sent and received simultaneously for continuous drilling

• No static points:

• Better hole cleaning

• Lower risk of stuck pipe

• No restrictions, normal drilling operations

(3) Geo-Pilot System:

• Overview:

• In 1989, Japan National Oil Corporation (JNOC) began research on a dynamic directional control system (RCDOS).

• In 1993, Sperry-Sun (USA) developed an automatic steering system for rotary drilling (AGS).

• In 1999, Sperry-Sun and Halliburton collaborated to introduce the Geo-Pilot rotary steerable system.

• Core Tool:

• Adjustable stabilizer: Provides adjustable and automatic directional control.

• Core Tool:

• Adjustable stabilizer with automatic directional control features:

1. Expanded stabilizer diameter adjustment range, enhancing directional control capability, e.g., Φ215.90 mm adjustable stabilizer can be adjusted between 184.15 to 215.90 mm.

2. Multiple control positions for stabilizers, using pulse drilling fluid control technology, electronics, and hydraulic pressure for positional control.

3. MWD provides real-time updates on the stabilizer's operating status.

4. Reduces pressure demands on the stabilizer without affecting drilling parameters, offering advantages in wellbore selection.

(4) Comparison of Three Typical Systems:

• Geo-Pilot System:

• Principle: Achieves effective directional control by adjusting the curvature of the drill string.

• Advantages: The tool provides precise directional control, unaffected by geological formations, and is highly effective in soft and uneven strata.

• Disadvantages: The drill string is prone to fatigue failure under high stress, requiring high-precision manufacturing to ensure effective steering.

• AUTOTRAK System:

• Principle: Uses static-based directional control, relying on biasing to alter the drill head's lateral force.

• Advantages: Uses mature technology to achieve precise directional control.

• Disadvantages: Complex downhole conditions, such as shifting operations, static outer sleeves, and limitations in miniaturization, can hinder the system's development.

• PowerDrive System:

• Principle: Uses dynamic biasing technology for directional control.

• Advantages: Simpler structural design with good miniaturization, enabling continuous rotation without stopping, making it suitable for deep, fast drilling in complex environments such as large deviations, multi-lateral wells, and high-difficulty operations.

• Disadvantages: Tool lifespan requires further improvement.

SMARTEC CSS delivers high performance and precision in rotary steerable system drilling technology, ensuring efficient wellbore trajectory control and maximizing drilling efficiency.