Factores Pronósticos Y Predictivos De Sobrevida

Subsea On-line Multiphase Fluid Sampling and Analysis 2.9.1

(SOFA)

The Subsea On-line multiphase Fluid sampling and Analysis (SOFA) system designed by Christian Michelsen Research in cooperation with the University of Bergen, is an autonomous metering station for permanent installation subsea. The SOFA project was planned to carryout representative fluid analysis. As can be seen in the Figure 2.26, the SOFA device is installed in the flow line and will be able to take a sample of the flow which then is stored for the time necessary to permit the separation of the different phases. The small gravitational separator tank in the SOFA device allows for multiple measurements designed to characterise the fluid. After the measurements are achieved, the sample is released into the flow, followed by the capture of a new sample intake (Erik et al., 2010).

List Benefits of Accurate Sampling 1.

Enhancement of oil recovery by securing detailed knowledge about individual well for content analysis

2.

Accurate fluid samples work to maintain lifetime accuracy and value of multiphase measurement systems by providing a source of verification and calibration

3.

Allocation and fiscal data points are provided through component analysis of hydrocarbons to determine the quality from each well

4.

Mitigate flow assurance issues by use of chemical and salinity analysis, for effective dosage of chemical injection strategy

5.

Optimized subsea processing and reducing environmental hazards through sampling efficiency of separation and waste water purity

6.

Acquiring accurate fluid properties from representative subsea samples reduce uncertainties in reservoir management which thus lead to increased oil recovery (IOR) and improved economics

7.

Subsea fluid sampling leads to significant cost savings in operational management on deepwater development

Figure 2-26 Sketch of SOFA Design for Continuous Sampling and Analysis of Multiphase Flow (Erik et al., 2010; Taylor and France, 2009)

Although fluid characterization is and has been the main focus for this subsea fluid sampling research, representative sampling of the flow can give valuable additional information. This information is however, available also from commercially available multiphase flow meters which have a requirement for periodic configuration and calibration. CFD modeling was used in the first design of the sampling probe on the SOFA, and such simulations will also be useful in the further developments of the fluid sampling system (Erik et al., 2010; Stephane et al., 2010). This may provide an integrated fluid sampling approach in providing solutions on challenges faced by the subsea industry.

Miniature Mass Spectrometer Applied to Subsea Sampling 2.9.2

The University of Liverpool had made a breakthrough in the miniaturisation of the mass spectrometer which is used mainly to identify sample compositions. It can detect and quantify the trace levels of oil recovery and production to be maximised, and discharge of hydrocarbons, as well as other unwanted contaminants which need to be minimised (Taylor and France, 2009). A Quadrapole retrofitted section of this spectrometer can be seen in Figure 2.27. The subsea industry could profit from this technology, as it could provide alternative method for the accurate characterisation of reservoir fluids.

Figure 2-27 Quadrapole (Taylor and France, 2009)

With the joint industrial project (JIP) support from BP, BG Group, Chevron, ConocoPhillips, and ENI, a full matrix of field trials were carried out in 2009 at Opus Plus Limited, in Orkney (ITF, 2009). Thus, the continued progress of this innovative technology could bring about viable alternative solutions for representative fluid analysis in future for the subsea industry.

2.10 Innovative Dedicated Fluid Sampling

The subsea flow control module has been on development in the past 5 years. But the cost of integration is high on CAPEX with increased OPEX on intervention operations. A major contribution to knowledge from this research is on the innovative application of this flow control module to the subsea production system (SPS). A new solution with sampling points (all related ROV interfaces, barriers etc.) packaged in a ‘Dedicated Fluid Sampling – Flow Control Module (FCM)’, was ‘conceptualised’ from this research studies to provide the benefit of ‘interchangeability’ with the standard production FCM (MPFM and Choke), captured as an optimised fluid sampling solution during concept selection phase of a deepwater project in West Africa. The FCM on the SPS is retrievable, so designing a ‘dedicated fluid sampling FCM’ was conceived in this research as a novel application to make subsea fluid sampling adaptable to the specific design of a production XT, which thus provide a suitable interface on ROV deployed sampling operations (Pinguet et al., 2014; Sbordone et al., 2012).

The principal for the FCM is to install components which may be retrieved several times during the life of the equipment. The design of the FCM is

based on a vertical deepwater Xmas Trees which is now available as ‘Enhanced Horizontal Xmas Trees’ (EHXT). The EHXT lower frame is designed in such a way as to support the addition of a FCM. The FCM design supports the ready removal and replacement of key EHXT equipment (chokes, MPFM, acoustic sand detector) as a single entity. It can be installed and retrieved on its own, or when fitted to the XT (Fenton, 2009; Bradley et al., 2006; Vick and James, 1995; Sbordone et al., 2012).

The Figure 2.28 presents the ‘dedicated fluid sampling FCM’ hardware with sampling hub or stab plate, developed with one of the EPC contractors on a deepwater project FEED. In the architecture, two sampling tubes with multiple quick connect (MQC) plates is designed to allow fluid sampling access to the production flowstream. This provides the possibility for retrofit into existing XT system on Brownfield, or Greenfield conceptual design with retrievability of the FCM technology. However, this solution could also be applied to other applications such as acid stimulation on the wellhead, etc. (Hall, 2011; Pinguet et al., 2014).

Figure 2-28 Dedicated Fluid Sampling FCM with Sampling Stab Plate (Source: Deepwater project)

The new conceptualised ‘dedicated fluid sampling FCM’ is significant, as it would enable improved representative sample capture, with tailored ROV interface valves for fluid sampling in the SPS. Therefore this novel approach provides the right operational access for production fluid sampling to maximise MPFM accuracy without need for conventional shut-in or introduction of external components to interrupt the process flowstream and hence production (Hall, 2011; Sbordone et al., 2012; Pinguet et al., 2014). With this sampling solution, the offshore industry would be able to adapt subsea fluid sampling operations interchangeably to different production XTs, to retrieve representative samples for meter measurements verification and thus, for proper assessment of fluid properties on production facilities.