The environment in which the search for oil is conducted beneath the surface of the seas is ever changing and often treacherous. It changes constantly due to the ebb and flow of the surface of the water and operation during inclement weather can be particularly treacherous. In deep water drilling, floating drill vessels are used, which are moored over the site of the well with large amounts of drilling tubular goods suspended from the anchored drilling barge, which is in constant motion. This barge is often more than a thousand feet from the ocean floor where drilling is occurring. Uncompensated stresses which compromise connections to various loads or the wellhead itself, can result in millions of dollars of additional repair expenses, long periods of downtime, and environmental disaster.
In these ocean drilling platforms, motion compensation systems (aka “heave compensation) are used to nullify the effects of ocean waves on the fixed and rotating drill string and bit, wellhead risers, or in other cases, crane head tension. Systems generally fall into two categories of either active or passive heave compensation systems with active being the more modern and sophisticated of the two. Some systems use a hybrid approach, relying on active to kick in for only the most rugged conditions. Each system typically relies on the operation of one or more hydraulic cylinders or accumulators which act as “springs” to keep the load at a constant level or tension. As a way of understanding the incredible responsibility of these systems, a good heave compensation system can keep a crane load steady to within a few centimeters, in heaving seas with 10-12 meter wave heights!
The Role of Linear Position Sensors in Heave Compensation Hydraulics.
In active heave compensation systems, hydraulic cylinders or accumulators are manipulated by control systems which drive or drain fluid from the cylinders in response to movement detected by an MRU (Motion Reference Unit). While there are a myriad of variations on heave compensation or riser/tensioner systems, most active systems will require closed loop feedback on the position of the shaft in a hydraulic piston or accumulator over what is typically a very long stroke length.. This is an essential data point for the control system that insures both safety, and the accuracy of the overall compensation.
CPI’s New Solution To An Old Problem – The SL 2000 Hydraulic Linear Position Sensor
CPI’s newest sensor, the SL2000, achieves a number of things that are critical to hydraulic cylinder manufacturers attempting to deploy on the drilling platform or under water at the wellhead or surface/sea edge.
ATEX & IECEx certifications – With these certifications, the SL2000 demonstrates all necessary intrinsic safety qualifications for sanctioned deployments in hazardous or combustible areas. These certifications cover regulatory requirements in both the United States and Europe.
Subsea Rated, Internal Mount Capable – The new design of the SL2000 uses a short rod magnetostrictive sensor to accurately report the position of our advanced drawwire sensor. The entire sensor can be completely submerged within hydraulic fluid inside the cylinder itself and supports standardized SEACON connectors with almost any desired voltage and current signaling. Our sensor has been qualified to 1 million cycles of operation at a pressure of 5000 ft in highly oxygenated seawater.
Long Stroke Lengths – Unlike other mechanically based or long rod systems, our sensor operates standard for a stroke of 10 meters. Our sensor is one of the few successfully deployed on telescoping cylinders. Even longer custom stroke lengths are available through our customization program.
Cost Effective – Advances in technology and design have made the SL2000 one of the most cost effective solutions for hydraulic cylinder position sensing in harsh duty environments.
The bottom line is this: If you haven’t looked looked at CPI linear position sensors for oilfield, or subsea mining hydraulics lately, then you haven’t really looked at CPI linear position sensors at all.
Call us today to discuss your application or visit us at http://cpi-nj.com