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  Last updated on 21/11/2019    (©  2001 - 2020   TECHNETEA) French

RSS - Rotary Steerable System
- a smart downhole tool -

Electronics Engineering

The experience of Technetea in real-time instrumentation in particular in the oil industry, naturally leads to developments for very specific equipments requiring a good expertise in high-temperature electronics able to withstand heavy vibration and shock.

For instance within the scope of an application as a Rotary Steerable System (RSS), Technetea is able to carry out the development of all the electronic parts and the embedded software to assure the power supply, the instrumentation, the control and the communication of the equipment, and simultaneously to do the development of the software programs for operations and transitional tests.

The material is designed in accordance with the ATEX standards (Potentially explosive atmospheres) IEC 60079-xx for a sure manipulation when operating at the rig floor.

Developing a Rotary Steerable System is a challenge much greater than for any other downhole tool. All the ingredients are put together for the project to become very problematic because of the severe conditions where the tool has to be operating in terms of high temperature, vibration and shock.

Vibration and accuracy doesn't commonly go well together, but an efficient Rotary Steerable System has to do measurements while the bit is really drilling. This is not the same context as for MWDs which often need the drilling to be temporarily stopped to be able to sample good data, even if the name MWD means "Measurement While Drilling" !

A Rotary Steerable System needs high-level electronic cards and good sensors, but the most important things are even more hidden in the embedded software. The electronic system has not only to give accurate information to perfectly know the drilling direction in real time, it also has to always take the good decision to correctly point the bit (or push the bit) whatever the formation. It has to embed enough intelligence to minimise the wellbore tortuosity, to not deviate from the targeted path, and to be efficient enough to reduce the drilling costs.

But electronics and embedded software are nothing without a good mechanical system. Such a project requires a high-value contribution of two specialities which are electronics and mechanics, each of them bringing their expertise in terms of specificities and performances.

While drilling, a lot of different situations may be encountered down the hole. Even experience always comes above all from the field, at Technetea we are fully convinced that a great part of the development has to be done through computer simulation. That is the reason why we develop our own informatics tools to model the tool and to simulate the downhole conditions as vibration, shock, radial forces, RPM, etc ... That way, simulated environmental conditions are injected in the processing algorithm in place of the raw data of the sensors, and all the filtered data coming from this virtual instrumentation as well as all the internally calculated parameters of the Rotary Steerable System (internal calculation results, control data, actuator controls, ...) can be seen graphically in real time, while the virtual tool strives to stay on the planned trajectory.

Analysing the reaction of the tool through computer simulation while it is activating the mechanical system to hold or to correct the deviation, is a convenient way to develop and improve the embedded control algorithm, by easily repeating all the critical sequences. It also speeds up the development phase, because the drill rate can be artificially accelerated only depending on the speed of the computer.

The processing algorithm can also be improved by replaying with the simulation software some chunks of data recorded during the field tests. It is an easy way to analyse a sequence to see if the tool correctly understood the situation, and to decide if a part of the firmware has possibly to be changed to maybe expect a more appropriate reaction of the tool next time.

Below, the setup of a computer simulation to study the behaviour of the Rotary Steerable System when crossing geological layers with different hardnesses.

RSS drilling RSS zoom

... to be continued ...