As oilfield engineering enjoys a resurgence of interest and investment, companies continue to look to advancements in technology to both reduce costs, and improve the safety of offshore drilling operations. In particular, active heave compensation systems use advanced hydraulic cylinders and accumulators to achieve a system that reduces the relative motion of the drill pipe and the seabed, improving both efficiency and safety. In the area of active heave compensation systems, CPI’s unique subsea position sensor is seeing deployment into these applications due to its unique versatility and durability. Specifically, manufacturers and system integrators specifying hydraulic cylinders and accumulators for active heave compensation, are finding that our ATEX and IEC-EX certified sensors are perfect for both subsea, and surface use, both inside and external to the hydraulics. Position Sensing in Heave Compensation Hydraulics is Absolutely Critical. Oilfield Applications which use the CPI advanced draw wire sensor include many different types of heave compensation systems. For most of these, the CPI SL-2000 Safety Rated Linear Position Sensor, is both a versatile, and a durable solution.
The CPI SL-2000, A study in Durability and Ingenuity Our solution to harsh duty hydraulic cylinder position detection is unique in the world, and is often the only practical solution to harsh environments, and long stroke cylinder applications. Here are a few of the characteristics of our robust sensor design.
Call CPI Today to discuss your Oilfield Hydraulics Position Sensing Needs Original content posted on https://www.cpi-nj.com/blog/heave-compensation-systems-for-offshore-drilling/ 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 https://www.cpi-nj.com Original content posted on https://www.cpi-nj.com/blog/motion-compensation-system-hydraulics-can-get-a-whole-lot-smarter/ Last year we discussed CPI sensor solutions for Oilfield hydraulic accumulators and cylinders, but in the fast-paced world of oilfield engineering, that was a long time ago.
For instance in 2016, CPI didn’t have a fully subsea capable (qualified to 5000ft), intrinsic safety rated (ATEX, IEC-EX) linear position sensor for hydraulic cylinders and accumulators. But now we do. Meet the CPI SL2000 The CPI SL2000 was specifically designed to meet the needs of heavy duty hydraulic system manufacturers, who seek robust, accurate, and reliable solutions to position or charge sensing in long stroke cylinders or accumulators. With a high-tech mechanical assembly and space-age material science, the CPI sensor surpasses the durability of all other sensor measurement technologies as well as other draw wire sensor technologies. For harsh duty internal or external cylinder applications, CPI’s technology may be the most hardened, reliable solution in the world. Marine Riser And Tensioner System Hydraulics Tensioner systems come in many designs but typically employ multiple hydraulic cylinders for stabilizers or the riser will buckle when the rig moves downward, and stretch when the rig rises. If you gather around the moon pool of any offshore rig or vessel during a storm you’ll see a riser/tensioner system hard at work. These systems use a bank of hydraulic accumulators to drive piston displacements in reaction to the heaving of a heavy sea. It is crucial that the tensioner can manage differential movements between the riser and the rig in real time to prevent shearing or undue stress on the wellhead. These huge and powerful accumulators are constructed using a gas and hydraulic fluid and can drive displacements from 10 to 15 meters. Using the SL 2000 in Oil Platform Hydraulics Because the core measurement technology of the sensor is mechanical draw wire, there are far less things to go wrong with a CPI sensor in a harsh environment. Furthermore the core sensing mechanics are incompressible allowing the sensor to operate inside the hydraulic cylinder, submersed in hydraulic fluid at full pressure. This kind of mounting flexibility makes for a clean integration into most cylinders and small external form factor for applications where a short magnetostrictive sensor is used as the transducer. A few other notes about our linear position sensor technology.
Riser Disconnect Sensing and Control CPI Sensors on the oil platform are also used provide critical feedback during a riser disconnect scenario. In this event, the riser must be disconnected before the rig is critically out of position with respect to the well head. Typically a tensioner ring employs six hydraulic accumulators with six valves controlled by the computer through signals from the valves and the CPI linear position sensor which is acting as the piston rod measuring system providing absolute (not relative) position measurement signals. Some systems are implemented with the cylinders mounted directly to the tensioner ring. In these systems, a riser disconnect detected by the CPI linear position sensor will cause the valve to limit the oil-flow and the riser will not gain momentum. The controlling system adjusts the position of the valves and the riser is brought up in a controlled way using input from CPI linear position sensors like the SL2000. Contact CPI for Questions About ATEX Rated, Subsea Capable, Harsh Duty Hydraulic Cylinder Position Sensors Our engineering team builds, installs, and qualifies these sensors uniquely into each application. Many options are available in the design of your sensor that can make it more robust, longer stroke, or even custom external mounting options for existing In-the-field cylinder applications. Please call our engineering team today to discuss your hydraulic accumulator based application or see all our harsh duty linear position sensors. Original content posted on https://www.cpi-nj.com/blog/marine-riser-and-tensioner-system-hydraulics-revisited/ One of the more challenging Hydraulic applications in the world exists far below the ocean, on the sea bed to be exact. A place where mother nature and the laws of entropy conspire to make all man made contraptions suffer, and challenge the ingenuity of engineers and scientists on a daily basis.
One such contraption is the large piston based hydraulic accumulators used in undersea mining and drilling operations as part of critical blowout preventer systems. In principle the operation of these systems is rather simple: The large hydraulic accumulator stands by full charged, ready to deliver massive force to the blowout preventer when a failure in the integrity of the pipeline is detected. The proper operation of the preventer, will prevent millions of gallons of crude oil from spilling into otherwise pristine waters. The failure of the blowout preventer on the other hand, can cause spectacular failures and environmental disaster as is all too well remembered from the Deepwater Horizon debacle that cost 11 lives and untold damage to wildlife and local ecology. Deploying Hydraulic Accumulators in a Sub-Sea Application Because all hydraulic Accumulators leak over time, they must be periodically replaced to insure that charge pressure has not dropped as to make the cylinder ineffective in an emergency. Imagine the cost involved of going down to the sea bed every 6 months to pull up and replace these accumulators, "just to be sure" they are in working condition. A better solution uses a CPI SL-1500 sensor on the sea bed to detect the position of the piston in the accumulator. As the pre-charge pressure of the accumulator leaks, the CPI sensor sends back extremely accurate position signals which tell technicians when they "really" have to replace an accumulator. By having real data on accumulator pressure, CPI sensors can save drilling operators hundreds of thousands of dollars by allowing them to intelligently delay the replacement of these Hydraulic cylinders until it is really needed. Alternately they can prevent a safety disaster by allowing operators to detect early failures of these accumulators. For more information on our Subsea sensors like the SL - 1500, visit our hydraulic accumulator applications page or visit www.cpi-nj.com. This content was originally published at https://www.cpi-nj.com/blog/the-challenge-of-subsea-position-sensing/ |
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