Downhole monitoring of real time pressure and temperature enables the operator to determine how the Progressive Cavity Pump (PCP) system is performing at its current settings. The pressure reading indicates both the pump intake pressure and the height of the fluid level above the pump. A predetermined fluid level (or pump intake pressure) can be maintained by slowing or speeding up the pump RPMs.
Maintaining the proper fluid level maximizes the pump performance and/or maintains the proper back pressure on the reservoir, which optimizes the well’s total production. When the downhole signal is hooked up to the R&MES Variable Frequency Drive (VFD), the internal software can automatically change the speed of the pump to optimize performance of the well.
General Design
R&MES’ Downhole Monitoring System consists of a digital electronic pressure and temperature gauge that is run into the well with the PCP completion string. A conductor cable is attached to the gauge to continuously transmit the data to the surface. The cable is a copper conductor insulated in a stainless steel tube. The cable is attached to the tubing string during run-in operations of the pump with protectors at each collar to prevent damaging the cable.
Deployment Applications
Maximum Operating Temperature: 260F (126C)
Maximum Pressure: 3,000PSI
Vertical or Deviated Wells
Integrated with Guardian II VFD or standalone
Real time pressure, temperature, vibration while operating
Shut-in / Build-Up Testing
System Components
1. Sensor – The downhole sensor provides accurate pressure and temperature readings to the surface at a rate of up to one reading per second. The rugged design ensures a long life and reliable data. The sensor is digital, which allows for multiple sensors to be run in the same well using only one cable.
2. Gauge Carrier - The gauge is secured inside a welded tube and mounted on the tubing string using a sidemount carrier to protect the sensor during run-in and extraction. This carrier is normally ported to allow intake pressure to the gauge. When discharge pressure readings are desired, the same mandrel can be changed to read the internal tubing pressure. Wells requiring intake and discharge sensors have a cable Y-splice attached to the carrier above the sensors.
3. Conductor Line – The downhole data is transmitted to the surface using the sensor conductor line. The line consists of an insulated copper wire inside a durable stainless steel tube. It is secured to the production tubing with protectors attached around the tubing collars during run-in. For applications where extra protection is needed, an additional hard polypropylene jacket (yellow) is molded over the line for extra abrasion resistance.
4. Cable Protectors – Protectors are needed for the sensor cable to prevent it from being pinched where it crosses the tubing collars during run-in operations. The greatest protection is provided by the cross-coupling clamps. Clamp sizes are determined by the size of the production string.
Some applications permit the use of a less expensive method of cable protection. Banded protectors are lightweight and require a metal band threaded through each end of the protector to secure it across the collar and hold the cable in place. These protectors can be appropriate for use in wells without much deviation.
5. Cable Exit Bushing – Where the sensor cable leaves the wellbore to continue to the data acquisition device, an exit bushing is needed to provide a seal around the cable. The type of bushing to use depends on where the cable exits the wellbore: either through the tubing hanger and out through the wellhead (Wellhead Exit Bushing), or through the casing (Casing Exit Bushing).
6. Gauge Interface Card – The surface data for the sensor is acquired through a gauge interface card. This circuit board outputs pressure and temperature to the VFD via a RS485 connection, allowing the drive to display downhole readings and control the pump RPMs based on the pump intake pressure. This real-time interface card can be mounted inside the drive or on the side of the drive if necessary. A data memory module and separate LCD display are available options.
7. Spooling / Tensioning Unit – The cable installation is accomplished with the use of a spooling / tensioning unit that spools out the conductor line as the pump / gauge system is being lowered into the wellbore. The pneumatic spooling unit runs off of the rig air system and provides a constant tension during run-in ensuring an effective installation. It is also used during extraction for an orderly spooling of the cable, preserving it for multiple runs of the same conductor line.