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Abstract BP Amoco's Pompano Phase II subsea development is located in the Gulf of Mexico in Block 28 of the Mississippi Canyon. The water depth is approximately 1,865 feet. The subsea template is tied back 4.5 miles to the Pompano platform located in Vioska Knoll Block 989. Phase II development is a 10-slot, integrated template/manifold. When the tubing retrievable safety valve (TRSV) in the primary and secondary production bores in two of the subsea wells failed, the wells had to be shut-in. An innovative through-flowline (TFL)-deployed insert surface-controlled subsurface safety valve (ISCSSV) enabled BPAmoco to restore operability and integrity to these wells. Root cause analysis had determined that declining reservoir pressures leading to excessive control-line differential pressures compromised at least of at least one of the tubing retrievable safety valves run with the original completions in 6 of the 8 subsea wells. Several options for remediation were considered:Floating rig interventions at an estimated cost of $6–10MM per well, or Codevelopment with an oilfield engineering/service company of a TFL-deployed insert SCSSV. The second option was chosen, and involved both design work, as well as a rigorous test program. The development and installation of these inserts allowed production in two subsea shut-in wells to be restored. This operation was the first in the Gulf of Mexico in which a TRSV lockout and the insert of a 3-in. insert flapper safety valve was deployed. BP Amoco's TFL requirements have led to significant enhancement of TFL technology in general, and the maturation of this project was able to provide BPAmoco with capability to realize a substantial saving in operating costs. Introduction The Pompano subsea production/manifold was installed in 1995 approximately 4.5 miles southeast of the platform. During the design of the subsea system, paraffin deposition in the wellbore and flowlines had been a prime concern of the project team. Because of this concern, the subsea system was designed to allow for through-flow-line (TFL) well servicing (Fig. 1) for removal of paraffin in the wellbores and flowlines in the event the primary paraffin prevention methods that had been designed into the system were insufficient or failed. The completion methods for paraffin inhibition included downhole chemical injection and insulation of the annulus using gelled mineral oil to keep wellhead temperatures above the cloud point. Since an initial requirement for the design of the subsea production manifold was to be able to perform all service functions from the host platform, the TFL paraffin control contingency would require that paraffin scraping be performed remotely from the platform. After three years of production, it was noted that several of the wells had developed leaks between the TRSV control line and production tubing. When pressure could no longer be maintained within the control lines to keep either of the dual TRSVs open in one well, BP Amoco launched an investigation to determine the root cause of the problem. The determination was finally made that excessive pressure differential between the control line and the wellbore due to reservoir pressure decline after the years of production had caused the seals in the TRSV to leak. Field procedures were then changed to monitor the pressure differential closely and to adjust as needed to meet the design specifications of the valve.
Sucker-rod artificial lift is one of the methods to lift hydrocarbons from a well to the surface, when the natural pressure from the reservoir cannot guarantee free flow. Presently, on the Oil and Gas market there is no downhole safety valve capable of closing and sealing on a reciprocating sucker rod string. This paper shows the design of an innovative Insert Sucker Rod Surface Controlled Sub Surface Safety Valve (ISRSCSSV)  capable of closing and sealing on a 1” sucker rod body, protecting the environment from spills due to uncontrolled blow out that may occur during the phases of oil production.
The ISRSCSSV  is composed of the following main sections: external housing, piston flow tube, sealing pads. The fail-safe design criteria implies that the ISRSCSSV  is normally closed, the pressure from the control line drives the piston flow tube connected to the sealing pads to the safety valve open position. The innovation resides in a variable geometry sealing mechanism, able to shut in the annular area between the 1” sucker rod and the valve external housing. The sealing path is composed of a segmented tapered pads system located at the end of the elastic fingers, travelling along a cone housing.
The ISRSCSSV  is interchangeable with a WRSCSSV, but, its installation and retrieving procedures collides with the insert rod pump anchor installation/retrieving procedure, so, an innovative insert rod pump was designed (Hybrid Pump) so that after installation through the sucker rod string, it acts as a tubing pump.
The uniqueness of this fail-safe safety valve is in the fact that it can be run downhole with the same sucker rod pumping string.
The ISRSCSSV  combined with the Hybrid Pump determines a new approach for retrofitting existing wells completed for spontaneous flow without costly workover interventions, representing a first fundamental step towards the application of the dual barrier policy on production wells.
Economic advantages: the innovation described, allows to recover a quantity of oil from marginal wells no longer having the energy to produce in free flowing, bringing more oil on the market at a sustainable production cost.
The first safety valve prototypes have been made and tested on a custom-built test bench and using a pilot well equipped to simulate real working conditions, initial results are very promising: tests of the sealing mechanism on the 1” rod have shown 0 leakage both with water and with nitrogen.
For deepwater field developments, subsea production systems are frequently envisaged by operators. A basic architecture consists of a central manifold gathering the production of several wells (satellite and/or template wells) and exporting, it to a process facility This scheme allows a large flexibility for the field development Today, installed subsea manifolds are not vex-$ numerous However, their number is expected to increase in the next couple of years.
The need to have cost-effective systems led oil companies to revise their philosophy reliability, simplicity and maintainability are now the main objectives in addition to the reduction of investment and operation costs For that purpose, new concepts and new technology for subsea production equipment have to be proposed New ideas such as insert components, running tools or specialized ROVs, flowlme/umbi1ical pulling-in and connection systems, operating robots, and new control system technology has been investigated and are presented in this chapter.
WHY MODULAR SUBSEA MANIFOLDS?
Drilling is now performed in deeper and deeper water, and any hydrocarbon strike in great water depth leads operators and equipment suppliers to develop various systems or concepts to bring such fields on stream In particular, subsea production technology is more and more considered as a viable alternative when the water depth increases It can permit the replacement of huge fixed platforms by simpler equipment lying on the sea bed Moreover, subsea technology permits a better exploitation of shallow reservoirs satellite wells are drilled vertically into different parts of the reservoir, which could not be reached by deviated drillings from a single fixed platform
Such subsea wells have to be linked to a surface facility Two alternatives are possible either individual flowlines link each well independently to the surface, or production of several wells is brought to a central point where it is commingled in a common export line towards a surface facility.
Since it is normally required that it shall be possible to isolate each well from the others, the junction of the satellite well flowlines and the main export line will require valves The structure receiving the valves, the piping, the flowline connecting equipment etc is the manifold. It is often also a central point for other functions, such as TFL-servicing, dispatching of water injection or gas-lift lines to certain wells, and dispatching of remote control links to the wells The manifold structure may also include subsea template wells In all cases, manifolds aim at reducing the number of production and control lines, and limiting (or suppressing in some cases) the surface equipment
Subsea equipment needs maintenance As it is considered difficult or even impossible to repair seabed equipment, a modular arrangement is used allowing the retrieval of defective equipment which can be repaired or replaced on the surface That reduces the duration of sea operations and improves the ability to maintain equipment in good and safe conditions Another reason for interest in a modular arrangement is the flexibility given for a field development Additional producing wells or injection wells can be envisaged in a step-by-step development.
Pilone, Salvatore (ENI) | Luppina, Salvatore (ENI) | Ricci Maccarini, Giorgio (ENI) | Sanasi, Carla (ENI) | Guglielmo, Carmelo (ENI) | Imbò, Pasquale (ENI) | Orsini, Paolo (Sivam) | Mennilli, Giuseppe (Fore Sivam Group) | Mauriello, Marco (Fore Sivam Group) | Schiavi, Andrea (Fore Sivam Group)
This paper summarizes the innovative peculiarities and the result of field trial installation on ENI well in South Italy of the new Insert Sucker Rod Surface Controlled Subsurface Safety Valve ISRSCSSV.
The ISRSCSSV, combined to a modified lock mandrel, is sucker rod retrievable and is possible to install in a WRSCSSV landing nipple. It is a normally closed failsafe safety valve so the CL pressure keeps the valve open (
The innovation resides in a variable geometry sealing mechanism, able to shut in the annular area between the sucker rod and the valve external body. The sealing path is composed of a segmented tapered pads system located at the end of the elastic fingers, travelling along a cone housing. The ISRSCSSV combined with the Hybrid Pump determines a new approach for interventions on existing wells completed for spontaneous flowing without workover, representing a first fundamental step towards the application of the dual barrier policy in production wells. The Innovation allows safely operating wells and recovering oil otherwise not economically advantageous (
The ISRSCSSV applies when need to convert a spontaneous flowing o ESP wells to the sucker rod artificial lift.
After the manufacturing of the ISRSCSSV, the related modified lock mandrel prototypes and the dedicated test fixture, the functional test performed as per
ISRSCSSV represents the first safety valve existing in the body of literature for wells with sucker rod artificial lift system, allowing the compliance to the dual barrier policy. Moreover, this approach gives the possibility to install and retrieve the safety valve always with the rods string, with considerable time and subsequent cost saving, safeguarding the protection of the environment and the Oil Company image (
The wire-line tubing perforator is an mechanically operated tool that is run onan ordinary steel measuring line into the tubing of a well, under pressure, todrive into a wall of the tubing, and securely lock in place, a tapered,cylindrical insert containing and orifice. Use of the perforator obviates thenecessity of pulling and rerunning the tubing to install jet collars or flowvalues, reduces the cost, and simplifies the task, of placing an oil well ongas-lift operation. More important, however, is the use of the tool with aremovable check value and stop, to provide a means of washing drilling mud fromthe annulus between the tubing and casing, and to complete the well for gaslift operation without exposing the producing formations to the mud column andwithout moving the tubing string.
This paper discusses the origin, development, and mechanics of the wire-lineperforator, the various purposes for which the tool was designed, and themethod of selecting orifice sizes for any depth, and gives the results obtainedthus far in practical application.
Origin and Development
Several years ago, a tool that could be lowered on an ordinary steel measuringline into the tubing of a well under pressure was designed and constructed forthe purpose of punching a hole in the tubing walls above a shale bridge thathad completely plugged the tubing of a well under pressure was designed andconstructed for the purpose of punching a hole in the tubing of a well in theLong Lake field, East Texas. The well was in a low, swampy area, whichexcessive rainfall had caused to be inaccessible by car or truck for about fourmonths. The only equipment at the well site consisted of an ordinary steel wireline that had been carried there to measure the depth of the bridge. Since apulling unit could not be moved to the well site, and as the pressure on thecasing was 2100 lb. per sq. in., it became apparent that the only way out ofthe predicament was to make a perforating tool that could be lowered into thetubing on a measuring line and operated under pressure. Thus, the firstwire-line tubing perforator was designed and built as an expedient, and was notused extensively until it had been redesigned to meet more frequent andincreasingly urgent needs.
Until recently, it was necessary to pull the tubing to install jet collars orflow valves when a well was to be placed on gas lift. Because most companieseither maintained or had access to pulling units and crews for this work littleor no thought had been given to eliminating or even simplifying this task. Whenthe manpower and steel storage became so acute, however, many operatorssuddenly found themselves without facilities to equip their wells for gaslifting. The wire-line tubing perforator already had been tried and provedsuccessful, therefore operators immediately requested its use to punch gas-jetholes in the tubing, to eliminate the pulling and running of tubingstrings.
The first deficiency revealed by more general use of the perforator lay in theinability to regulate the size of the hold punched through the tubing.