Wireless data links for oil and gas well monitoring

The Challenge

Working across the entire oil and gas well life cycle, Expro’s core business is in well flow optimisation. The company combines innovative disruptive technology with high quality data across well testing, subsea well access, well intervention and production solutions, to deliver a highly accurate, state-of-the-art service. Sensors for monitoring temperature, pressure, flow and other key parameters are sometimes deployed deep underground for months at a time in order to monitor the health of a well.

Expro had a requirement for several sensors to be able to communicate with each other when located side-by-side. Each sensor unit is encased in several millimetres of solid stainless steel in order for it to survive temperatures as high as 175°C and pressures of up to 20,000psi, as well as the presence of corrosive fluids.

The Approach

Such tough environmental conditions make any kind of cable-and-connector solution impossible and so a two-way wireless data link was proposed. Not only must the wireless link communicate through completely sealed steel enclosures, but the electronic circuitry must survive incredibly high temperatures, making the choice of available components very limited. Our radio and electromagnetics specialists examined a number of possible modes of coupling between sensor units, including acoustic, resistive, magnetic and electromagnetic. We were quickly able to predict a solution, and set about determining the means to maximise the performance, as well as ways to encode data efficiently and reliably using only the simplest circuitry. We then used a mixture of physics theory, circuit simulation, electromagnetics modelling and hardware prototypes modelling to build a room-temperature concept demonstrator which Expro was able to evaluate at its labs. The final design could then be released to Expro engineers for incorporation into the next generation of sensors.

THE OUTCOME

We were able to show, by detailed understanding of the physics behind the problem, that our design, modulation scheme and wireless protocol were optimal for the required data rate and wireless range. The demonstrator system met all of Expro’s data rate, range, size, complexity and power consumption requirements, and was developed in only four months.