Connecting fibre optic communications on deepwater subsea pump project
Customer’s problem
BP has been producing oil on the King field in the Gulf of Mexico since 2002. In order to increase recovery and extend the economic life of the field, the company embarked on a project to install two subsea multi-phase booster pumps. As part of this project, there was a requirement to provide communications for monitoring pump speed and lubricant oil pressure. In order to ensure high transmission speed, fibre optics were specified, and Expro was selected as one of the connector vendors.
Expro’s solution
The solution comprised a number of connectors and ancillary equipment from Expro’s FoeTRON product range, including an umbilical termination unit, optical fibre management units, and wet mate hybrid electro-optic connectors, some utilising both electrical and optical elements. All components were interconnected using oil filled pressure balanced hoses.
Results
The system was successfully deployed in October 2007.
These challenges came mainly as a result of a shore-based underwater trials programme devised to replicate the operational interface prior to subsea installation. The objective of the trials was to demonstrate that successful mating and demating of a wet mate plug/receptacle connector pair could be achieved for a specified number of mate/demate cycles against a defined operational interface provided by a ROV.
Consultation with the customer took place to review the impact on the impending deployment and to make proposals for risk mitigation. It was mutually agreed to proceed with deployment but with a revised approach to ROV actuation, thereby eliminating the potential for damage as experienced in the trials.
Technologies used
The FoeTRON connector range has, at its heart, a method which provides accurate and repeatable subsea mating and aligning of two single mode optical fibres, the core of which are only nine microns in diameter. Standard telecommunications style ceramic ferrules and aligning split sleeves are housed within oil filled housings, utilising Expro’s renowned CE (controlled environment) principle – this ensures all critical components are protected at all times from seawater ingress, and are pressure balanced to minimise stress and allow use in deepwater (the water depth on the King field ranges from 1600 to 1800m). Expro’s AquaTRON oil filled hose is used as a conduit throughout, and at the critical umbilical termination area, an epoxy based penetrator design is used as a pressure barrier.
Due to the effects of pressure on optical joints, investment had to be made in high strength fusion splicing and recoating equipment, to ensure the optical performance was not affected during the life of the product. Test and measuring equipment was also required, with optical loss test sets being required for FAT, and OTDRs (Optical Time Domain Reflectometer) for site terminations.
Clamp-on real-time production surveillance
Customer’s problem
These gas fields in the UK have been in operation since the early 1980’s. The fields’ combined reserves are among the largest in the UK shelf and production from these assets plays a key role in satisfying UK national gas demand. The customer is responsible for the management of a field comprising a Central Production Platform (CPP) and five un-manned satellite platforms. One platform is connected directly to the CPP via a gantry. The remaining platforms are several miles from the CPP and produced gas is transported to the CPP via 24” lines on the seabed.
Over the last 20 years the production rates have dropped across the field and original processing equipment, including test separators, have had to be de-commissioned and removed from the platforms. Due to the lack of measurement equipment, the customer had no effective way of measuring individual well production. The customer considered installing invasive meters (vortex instruments) however the cost and complexity of installation and the prospect of lost production during installation made that option unattractive.
Expro’s solution
As the customer had no way of identifying the flow rates from each remote platform, or indeed each individual well, in 2008 they embarked on a trial of Expro’s PassiveSONAR™ meter installed on a 24” line from one platform to the CPP, cross checking the flow rates from the meter against the main CPP separator.
This trial proved very successful and through testing by difference, the customer was able to check flow rates from each of the 12 individual wells. As the field is required to provide increased production to match UK national demand, it was imperative that the customer develop a surveillance strategy to support that goal. In 2009, the customer embarked on a project to:
monitor individual well production performance
identify wells affected by salt build up and target them for workover
workover using fresh water flushing to remove or reduce halite deposits
Ultimately, this project involved the installation and evaluation of Expro’s 8” ActiveSONAR™ meters on two wells where the halite deposit problem was particularly severe. The evaluation was a success, and the customer is installing meters on an additional 12 wells in this field.
Results
Both the ActiveSONAR and the PassiveSONAR meters installed on the platform showed very close agreement with the available flow references. In particular, the ActiveSONAR meter showed very good low flow monitoring capabilities, with measurements down to 1.7 feet per second at 25 barg with relatively high liquid loading.
The results proved that Expro’s clamp-on sonar technology offers a convenient, cost effective way to provide wellhead surveillance on offshore platforms. The sonar meter’s ability to provide accurate readings at low flow conditions was also proven. The presence of liquids in the gas stream did not impact the functionality of the sonar meter. The ActiveSONAR meters are now installed for permanent production surveillance. The meters were tied into the customers’ platform DCS system using existing protocols and channels with minimal additional work required.
During testing of the Passive and ActiveSONAR meters, the customer observed that some wells were more susceptible to flow reduction than others, in some instances losing production completely. Based on this information, Expro’s Well Test Team were invited to use their innovative downhole video tool to investigate the cause of the reduced flow rates on one well. This video showed that the well perforations and the riser were slowly being choked by salt deposits.
Having completed the video, the Expro Well Test Team was then mobilised to provide a fresh water flushing service for the well. This service successfully removed the salt deposit, returning production rates to normal levels.
Technologies used Both ActiveSONAR and PassiveSONAR meters were successfully employed by Expro Meters for wellhead production surveillance. PassiveSONAR is the technology that pioneered clamp-on sonar metering. It uses passive listening technology to determine volumetric flow rate. PassiveSONAR is well-suited for high rates and high liquid loadings.
The ActiveSONAR meter uses pulsed-array sensors to track the speed of coherent flow structures. The technology offers enhanced performance for surveillance applications where low flow rates and thick walled pipes present measurement challenges for traditional clamp-on meters. Expro’s downhole video tool was used to discover the root cause of the reduced flow rates on wells affected by salt deposits. Fresh water flush kit was used to remove the salt deposits and bring the wells back into normal production.
Clamp-on sonar surveillance to quantify effectiveness of gas well deliquification
Customer’s problem
As production rates decline over the natural life of a gas well, gas flow velocities can decrease to the point at which they are insufficient to lift produced reservoir liquids. These liquids then build-up within the well bore, back-pressuring the well and further reducing production rates. Left unchecked, this build-up of liquids can eventually “kill” the well.
Our customer was experiencing declining gas production on a dry gas reservoir platform. The declining production was attributed to the build-up of liquids within the well bore and the customer was preparing to undertake a deliquification campaign to increase production.
While many options are available to remove the liquids from the well bore, the customer opted to use foam treatment to remove liquids from their wells. In this procedure, chemical foaming agents are injected into the liquid column, foaming the liquids. In this foamed state, the liquid is more readily lifted from the well by the produced gas. As the liquid column unloads, gas production is increased.
As part of the deliquification program, the customer opted to deploy a temporary well test separator to measure the effectiveness of the foam treatment in enhancing production. While conventional test separators are an effective means of measuring gas well production rates, conventional well test packages can significantly increase the cost of deliquification programs. Therefore, the customer was interested in identifying and validating a more cost-effective means of establishing the effectiveness of their deliquification program.
Expro’s solution Expro Meters provide clamp-on sonar surveillance to measure gas production rates from gas and gas condensate wells. Using clamp-on sonar flow meters and global service delivery capability, Expro Meters provide well test quality surveillance of produced gas rates with a single field service technician using helicopter deployable equipment on a one day call-off basis.
Having successfully trialled Expro Meters surveillance services on a gas production platform using an in-line venturi meter as a reference, the customer was interested in evaluating Expro Meters’ ability to provide cost effective surveillance to monitor the effectiveness of their deliquification program.
To evaluate the clamp-on wellhead sonar surveillance service, a sonar meter was clamped-on to temporary pipe work on the inlet of the test separator. In this configuration, the results from the sonar meter could be compared directly with the results from the gas leg of the separator. Additionally, a sonar meter was installed on production piping to provide a measurement of well production without the restriction of the well test package.
Results Expro Meters’ clamp-on sonar meters were tested on four wells, with each operating over multiple flow rates. Gas rates provided by the sonar meters were within 5% of the gas rates reported from the test separator, validating the suitability of sonar meters to provide clamp-on gas flow rates with comparable accuracy to a well test separator.
Sonar meters provided an additional benefit by providing real-time gas flow rates from the moment the well was opened up and throughout the evaluation period. The compact and lightweight sonar equipment was deployed and operational within one day of call-off. This small footprint and rapid deployment capability makes sonar surveillance particularly well-suited for the operational constraints of normally unmanned platforms. The clamp-on sonar surveillance provided by Expro Meters was shown to provide a more convenient and cost-effective means of quantifying the effectiveness of well deliquification than conventional well test separators.
The test results gave the client a clear picture of well performance, and provided timely indication of the effectiveness of the deliquification program. This deliquification program resulted in an over 50% increase in production.
Technologies used
Expro Meters deployed both ActiveSONAR™ and PassiveSONAR™ technologies during the test. The combination of the two technologies ensures robust measurement over a wide range of gas, liquid and foam production conditions.
PassiveSONAR is the technology that pioneered clamp-on sonar metering of the predominant phase in a multiphase environment. It uses passive listening technology to determine volumetric flow rate. The technology is well-suited for high rates and high liquid loadings.
ActiveSONAR is the next generation of clamp-on Sonar technology. ActiveSONAR uses pulsed-array sensors to track the speed of coherent flow structures. The pulse array technology provides enhanced signal to noise providing flow rate measurement down to very low flow rates with high turndown capability.
Clamp-on sonar well testing on a mature gas condensate field
Customer’s problem
Marathon Oil UK owns a 38 percent interest in the East Brae Field, a mature gas-condensate field in the Central North Sea. Marathon has undertaken several projects in the East Brae Field to maximise production from this field, balancing the need for periodic well testing and the requirement to optimise production from the field’s low pressure wells.
Marathon has modified its production facilities to enable the test separator to be operated at a reduced pressure thereby allowing it to act as a low pressure production separator to sustain or boost production from the field’s low pressure wells. With the test separator operating in this mode, Marathon can maximise production from its struggling well stock.
Although overall field production is increased, the conversion of the test separator into a low pressure production separator precludes its use for production surveillance. In order to measure the production on a well by well basis, the low pressure separator has to be temporarily reverted into a test separator, causing decreased production of the low pressure wells during this period. This results in deferred production during well testing. Ideally, Marathon seeks a well testing solution that would allow it to continue to produce all wells at the optimum production rates during well testing periods.
Expro’s solution
Expro proposed that their sonar surveillance services could be used in place of the test separator for well testing. This testing would allow the well production rates to be accurately determined without the trade-off of decreased production during well testing.
A trial of Expro’s ActiveSONAR™ and PassiveSONAR™ meters has been implemented on two separate occasions on the East Brae Platform by Expro Meters’ expert Surveillance Engineer to:
Prove that the meters can be applied to East Brae wells to determine well performance (accuracy +/- 10%)
To prove the applicability of the flow meters over wells with a wide range of gas/liquid ratios
To evaluate the merits of both the ActiveSONAR and PassiveSONAR flow meters
Minimise the production losses associated with traditional well testing
The meters were installed and supported by one engineer and rigged up ready for operation in a matter of hours.
Results Both the ActiveSONAR and the PassiveSONAR meters installed on East Brae showed very close agreement with recent test separator values for the predominant gas phase. If the gas trends for a well are in line with expectations then the test can be used for allocation purposes and well performance monitoring. If the test result is outside of expectations then the well will be flagged for a full two-phase well test in the test separator when an opportunity arises.
The ActiveSONAR and PassiveSONAR meters took less than one hour each to rig up. The kit is packaged appropriately for convenient transport by helicopter. The clamp-on well testing can be performed by one trained Expro Field Surveillance Engineer.
Based on contracting with Expro to provide clamp-on well testing services, Marathon has the potential to save over £150,000 for each testing campaign.
Technologies Used Both ActiveSONAR and PassiveSONAR meters were successfully trialled by Expro Meters for wellhead production surveillance.
PassiveSONAR is the technology that pioneered clamp-on Sonar metering. It uses passive listening technology to determine volumetric flow rate. PassiveSONAR is well-suited for high rates and high liquid loadings.
The ActiveSONAR meter uses pulsed-array sensors to track the speed of coherent flow structures. The technology offers enhanced performance for surveillance applications where low flow rates and thick walled pipes present measurement challenges for traditional clamp-on meters.
Expro Meters automated well test reporting tools were used to generate a clear, concise and accurate well test report for the customer on a timely basis.
Connectors & Measurements
Connecting fibre optic communications on deepwater subsea pump project
Customer’s problem
BP has been producing oil on the King field in the Gulf of Mexico since 2002. In order to increase recovery and extend the economic life of the field, the company embarked on a project to install two subsea multi-phase booster pumps. As part of this project, there was a requirement to provide communications for monitoring pump speed and lubricant oil pressure. In order to ensure high transmission speed, fibre optics were specified, and Expro was selected as one of the connector vendors.
Expro’s solution
The solution comprised a number of connectors and ancillary equipment from Expro’s FoeTRON product range, including an umbilical termination unit, optical fibre management units, and wet mate hybrid electro-optic connectors, some utilising both electrical and optical elements. All components were interconnected using oil filled pressure balanced hoses.
Results
The system was successfully deployed in October 2007.
These challenges came mainly as a result of a shore-based underwater trials programme devised to replicate the operational interface prior to subsea installation. The objective of the trials was to demonstrate that successful mating and demating of a wet mate plug/receptacle connector pair could be achieved for a specified number of mate/demate cycles against a defined operational interface provided by a ROV.
Consultation with the customer took place to review the impact on the impending deployment and to make proposals for risk mitigation. It was mutually agreed to proceed with deployment but with a revised approach to ROV actuation, thereby eliminating the potential for damage as experienced in the trials.
Technologies used
The FoeTRON connector range has, at its heart, a method which provides accurate and repeatable subsea mating and aligning of two single mode optical fibres, the core of which are only nine microns in diameter. Standard telecommunications style ceramic ferrules and aligning split sleeves are housed within oil filled housings, utilising Expro’s renowned CE (controlled environment) principle – this ensures all critical components are protected at all times from seawater ingress, and are pressure balanced to minimise stress and allow use in deepwater (the water depth on the King field ranges from 1600 to 1800m). Expro’s AquaTRON oil filled hose is used as a conduit throughout, and at the critical umbilical termination area, an epoxy based penetrator design is used as a pressure barrier.
Due to the effects of pressure on optical joints, investment had to be made in high strength fusion splicing and recoating equipment, to ensure the optical performance was not affected during the life of the product. Test and measuring equipment was also required, with optical loss test sets being required for FAT, and OTDRs (Optical Time Domain Reflectometer) for site terminations.
Clamp-on real-time production surveillance
Customer’s problem
These gas fields in the UK have been in operation since the early 1980’s. The fields’ combined reserves are among the largest in the UK shelf and production from these assets plays a key role in satisfying UK national gas demand. The customer is responsible for the management of a field comprising a Central Production Platform (CPP) and five un-manned satellite platforms. One platform is connected directly to the CPP via a gantry. The remaining platforms are several miles from the CPP and produced gas is transported to the CPP via 24” lines on the seabed.
Over the last 20 years the production rates have dropped across the field and original processing equipment, including test separators, have had to be de-commissioned and removed from the platforms. Due to the lack of measurement equipment, the customer had no effective way of measuring individual well production. The customer considered installing invasive meters (vortex instruments) however the cost and complexity of installation and the prospect of lost production during installation made that option unattractive.
Expro’s solution
As the customer had no way of identifying the flow rates from each remote platform, or indeed each individual well, in 2008 they embarked on a trial of Expro’s PassiveSONAR™ meter installed on a 24” line from one platform to the CPP, cross checking the flow rates from the meter against the main CPP separator.
This trial proved very successful and through testing by difference, the customer was able to check flow rates from each of the 12 individual wells. As the field is required to provide increased production to match UK national demand, it was imperative that the customer develop a surveillance strategy to support that goal. In 2009, the customer embarked on a project to:
Ultimately, this project involved the installation and evaluation of Expro’s 8” ActiveSONAR™ meters on two wells where the halite deposit problem was particularly severe. The evaluation was a success, and the customer is installing meters on an additional 12 wells in this field.
Results
Both the ActiveSONAR and the PassiveSONAR meters installed on the platform showed very close agreement with the available flow references. In particular, the ActiveSONAR meter showed very good low flow monitoring capabilities, with measurements down to 1.7 feet per second at 25 barg with relatively high liquid loading.
The results proved that Expro’s clamp-on sonar technology offers a convenient, cost effective way to provide wellhead surveillance on offshore platforms. The sonar meter’s ability to provide accurate readings at low flow conditions was also proven. The presence of liquids in the gas stream did not impact the functionality of the sonar meter. The ActiveSONAR meters are now installed for permanent production surveillance. The meters were tied into the customers’ platform DCS system using existing protocols and channels with minimal additional work required.
During testing of the Passive and ActiveSONAR meters, the customer observed that some wells were more susceptible to flow reduction than others, in some instances losing production completely. Based on this information, Expro’s Well Test Team were invited to use their innovative downhole video tool to investigate the cause of the reduced flow rates on one well. This video showed that the well perforations and the riser were slowly being choked by salt deposits.
Having completed the video, the Expro Well Test Team was then mobilised to provide a fresh water flushing service for the well. This service successfully removed the salt deposit, returning production rates to normal levels.
Technologies used
Both ActiveSONAR and PassiveSONAR meters were successfully employed by Expro Meters for wellhead production surveillance. PassiveSONAR is the technology that pioneered clamp-on sonar metering. It uses passive listening technology to determine volumetric flow rate. PassiveSONAR is well-suited for high rates and high liquid loadings.
The ActiveSONAR meter uses pulsed-array sensors to track the speed of coherent flow structures. The technology offers enhanced performance for surveillance applications where low flow rates and thick walled pipes present measurement challenges for traditional clamp-on meters. Expro’s downhole video tool was used to discover the root cause of the reduced flow rates on wells affected by salt deposits. Fresh water flush kit was used to remove the salt deposits and bring the wells back into normal production.
Clamp-on sonar surveillance to quantify effectiveness of gas well deliquification
Customer’s problem
As production rates decline over the natural life of a gas well, gas flow velocities can decrease to the point at which they are insufficient to lift produced reservoir liquids. These liquids then build-up within the well bore, back-pressuring the well and further reducing production rates. Left unchecked, this build-up of liquids can eventually “kill” the well.
Our customer was experiencing declining gas production on a dry gas reservoir platform. The declining production was attributed to the build-up of liquids within the well bore and the customer was preparing to undertake a deliquification campaign to increase production.
While many options are available to remove the liquids from the well bore, the customer opted to use foam treatment to remove liquids from their wells. In this procedure, chemical foaming agents are injected into the liquid column, foaming the liquids. In this foamed state, the liquid is more readily lifted from the well by the produced gas. As the liquid column unloads, gas production is increased.
Expro’s solution
Expro Meters provide clamp-on sonar surveillance to measure gas production rates from gas and gas condensate wells. Using clamp-on sonar flow meters and global service delivery capability, Expro Meters provide well test quality surveillance of produced gas rates with a single field service technician using helicopter deployable equipment on a one day call-off basis.
Having successfully trialled Expro Meters surveillance services on a gas production platform using an in-line venturi meter as a reference, the customer was interested in evaluating Expro Meters’ ability to provide cost effective surveillance to monitor the effectiveness of their deliquification program.
To evaluate the clamp-on wellhead sonar surveillance service, a sonar meter was clamped-on to temporary pipe work on the inlet of the test separator. In this configuration, the results from the sonar meter could be compared directly with the results from the gas leg of the separator. Additionally, a sonar meter was installed on production piping to provide a measurement of well production without the restriction of the well test package.
Results
Expro Meters’ clamp-on sonar meters were tested on four wells, with each operating over multiple flow rates. Gas rates provided by the sonar meters were within 5% of the gas rates reported from the test separator, validating the suitability of sonar meters to provide clamp-on gas flow rates with comparable accuracy to a well test separator.
Sonar meters provided an additional benefit by providing real-time gas flow rates from the moment the well was opened up and throughout the evaluation period. The compact and lightweight sonar equipment was deployed and operational within one day of call-off. This small footprint and rapid deployment capability makes sonar surveillance particularly well-suited for the operational constraints of normally unmanned platforms. The clamp-on sonar surveillance provided by Expro Meters was shown to provide a more convenient and cost-effective means of quantifying the effectiveness of well deliquification than conventional well test separators.
The test results gave the client a clear picture of well performance, and provided timely indication of the effectiveness of the deliquification program. This deliquification program resulted in an over 50% increase in production.
Technologies used
Expro Meters deployed both ActiveSONAR™ and PassiveSONAR™ technologies during the test. The combination of the two technologies ensures robust measurement over a wide range of gas, liquid and foam production conditions.
PassiveSONAR is the technology that pioneered clamp-on sonar metering of the predominant phase in a multiphase environment. It uses passive listening technology to determine volumetric flow rate. The technology is well-suited for high rates and high liquid loadings.
ActiveSONAR is the next generation of clamp-on Sonar technology. ActiveSONAR uses pulsed-array sensors to track the speed of coherent flow structures. The pulse array technology provides enhanced signal to noise providing flow rate measurement down to very low flow rates with high turndown capability.
Clamp-on sonar well testing on a mature gas condensate field
Customer’s problem
Marathon Oil UK owns a 38 percent interest in the East Brae Field, a mature gas-condensate field in the Central North Sea. Marathon has undertaken several projects in the East Brae Field to maximise production from this field, balancing the need for periodic well testing and the requirement to optimise production from the field’s low pressure wells.
Marathon has modified its production facilities to enable the test separator to be operated at a reduced pressure thereby allowing it to act as a low pressure production separator to sustain or boost production from the field’s low pressure wells. With the test separator operating in this mode, Marathon can maximise production from its struggling well stock.
Although overall field production is increased, the conversion of the test separator into a low pressure production separator precludes its use for production surveillance. In order to measure the production on a well by well basis, the low pressure separator has to be temporarily reverted into a test separator, causing decreased production of the low pressure wells during this period. This results in deferred production during well testing. Ideally, Marathon seeks a well testing solution that would allow it to continue to produce all wells at the optimum production rates during well testing periods.
Expro’s solution
Expro proposed that their sonar surveillance services could be used in place of the test separator for well testing. This testing would allow the well production rates to be accurately determined without the trade-off of decreased production during well testing.
A trial of Expro’s ActiveSONAR™ and PassiveSONAR™ meters has been implemented on two separate occasions on the East Brae Platform by Expro Meters’ expert Surveillance Engineer to:
The meters were installed and supported by one engineer and rigged up ready for operation in a matter of hours.
Results
Both the ActiveSONAR and the PassiveSONAR meters installed on East Brae showed very close agreement with recent test separator values for the predominant gas phase. If the gas trends for a well are in line with expectations then the test can be used for allocation purposes and well performance monitoring. If the test result is outside of expectations then the well will be flagged for a full two-phase well test in the test separator when an opportunity arises.
The ActiveSONAR and PassiveSONAR meters took less than one hour each to rig up. The kit is packaged appropriately for convenient transport by helicopter. The clamp-on well testing can be performed by one trained Expro Field Surveillance Engineer.
Based on contracting with Expro to provide clamp-on well testing services, Marathon has the potential to save over £150,000 for each testing campaign.
Technologies Used
Both ActiveSONAR and PassiveSONAR meters were successfully trialled by Expro Meters for wellhead production surveillance.
PassiveSONAR is the technology that pioneered clamp-on Sonar metering. It uses passive listening technology to determine volumetric flow rate. PassiveSONAR is well-suited for high rates and high liquid loadings.
The ActiveSONAR meter uses pulsed-array sensors to track the speed of coherent flow structures. The technology offers enhanced performance for surveillance applications where low flow rates and thick walled pipes present measurement challenges for traditional clamp-on meters.
Expro Meters automated well test reporting tools were used to generate a clear, concise and accurate well test report for the customer on a timely basis.