1. Preparation for Field Trials
Objective: To prepare and qualify the OIWM for safe and reliable use in a field trial

Fouling
During the CoSWaSS trials a coating of corrosion products and salt deposits partially obscured the optical window and promoted oil filming. The coating caused a change in the response of the OIWM to oil concentration during the tests. Two methods of correcting for the presence of fouling were devised, one used signal analysis to correct the OIWM measurements and the other used maintenance intervention to physically clean the window area.
A short study funded by CoSWaSS is currently ongoing which is due for completion end September 2001 which will recommend one or more optimum technologies. Further investigation of the types of fouling likely to occur and methods of prevention or removal will be required to define and implement the best solution(s) for the OIWM. The investigation will identify the most prevalent types of fouling and the strategies which may be used to prevent the fouling, or to remove the fouling from the optical window. Help will be sought from participants in providing data on types and quantities of fouling/ scaling encountered in practice and in accessing existing emerging technologies. Once the most appropriate anti-fouling technology has been identified, it will be implemented in an OIWM for a field trial.

Concentration Algorithm
During the CoSWaSS trials the influence of various parameters, such as temperature, pressure and produced water salinity on the OIWM response were characterised. Resulting from this characterisation a prototype algorithm for predicting the oil concentration in a produced water stream has been derived. The algorithm will be further refined, implemented into the OIWM software and then tested during the field trial.

Field test site
Suitable test sites will be sought from the project sponsors from the start of the project. During this stage in the project the best match to the requirements will be identified. As part of this process the deviations between the OIWM specification and the test site's required standards will be identified, and a work package to carry out any required modifications will be specified. A draft specification for a field trial site is attached as Appendix 2.

OIWM modifications
The specified OIWM modifications, expected to at least require qualification of the OIWM prototype for hazardous area use, will be made during this task. Other required changes, such as the addition of a modem to permit remote access, will be made simultaneously. Once the modifications and qualifications have been achieved, the OIWM will be re-built and characterised in readiness for a field trial.

2. Field Trial 1
Objective: Determine the effectiveness of the anti-fouling technology and the suitability of the OIWM for field use

The trial will be planned for a six month duration on a topsides produced water re-injection or discharge line. Following installation and commissioning the topsides prototype OIWM will be left to be run by the site operations group, with data analysis and support provided by KOP throughout the trial. A report will detail the performance of the system during the trial and describe any improvements required prior to qualification of the final OIWM design.

3. OIWM modifications
Objective: Implement changes which are required as a result of the field trial and concurrent design work; re-build and re-characterise in readiness for a further field trial.

It is anticipated that some modifications may be required to improve the OIWM performance in combating fouling and scaling, or in other functional aspects. As it is not possible to define these changes prior to the field trial, the cost of this segment of work is estimated.

4. Subsea OIWM design
Objective: A specification for the subsea OIWM will be produced, and this will form the basis for the subsea design package.

The design of the OIWM will be largely common between topsides and subsea versions. A basis of design will be formulated for the OIWM and will cover the requirements for topsides, subsea and down-hole versions of the instrument. From this overall basis of design the subsea specification will be produced. The design work for the subsea OIWM is anticipated to fall into three main categories; system and electronics design; software design; and packaging design.

Electronics and system design
As a result of the testing carried out on the CoSWaSS OIWM, some of the current electronics may be redundant. If significant redundancy can be identified there will be benefits to reliability in simplifying the system design. In addition there may be significant benefits to be gained in re-design of some system components for the subsea OIWM to improve reliability and to reduce the size and weight of the packaging required.

Software design
Good software design is critical to the reliability and successful operation of subsea instruments. The software will be split into modules allowing operation of the OIWM in different modes. These modes will allow zero calibration, normal operation and software download so that should software up-grades become available these can be downloaded into the in-situ instrument. The software will be ported onto the KOP standard subsea operating system and will provide an interface compatible with subsea control modules.

Subsea packaging design
As part of the marinisation process the OIWM will be packaged into a suitable containment for subsea application. The containment has to fulfil key criteria as defined in the basis of design. The containment will protect the instrument from the external environment, maintain a stable internal environment and ensure that temperature fluctuations, shock and vibration do not adversely affect the integrity of the instrument. The experience which KOP has accumulated over many years of designing, building and deploying subsea electronics will be used to ensure the highest standard of design for the subsea OIWM.
The qualification procedure against which the subsea OIWM will be tested to prove its design will be defined against the basis of design. The subsea OIWM will be tested against the qualification procedure to ensure the integrity of the instrument is adequate for subsea use.

5. Field Trial 2
Objective: Determine the effectiveness of the modifications to the OIWM following the first field trial. Feed in any design improvements required prior to finalising the design of the subsea OIWM as the trial progresses.

The trial will be similar to the first field trial, planned for a six month duration on a topsides produced water re-injection or discharge line. Following installation and commissioning the OIWM will be left to be run by the site operations group, with data analysis and support provided by KOP throughout the trial. A report will detail the performance of the system during the trial. It is proposed that the unit used will still be the topsides OIWM since subsea design and implementation will not be complete before the start of this trial - although the steering group may determine any changes as the project progresses.

6. Qualification
Objective: Qualify the subsea OIWM for immunity to environmental factors which may adversely influence its performance and for performance in measurement of oil in water

Environmental qualification
Once equipment is deployed subsea it becomes very time-consuming and expensive to retrieve for repair or modification. Because of this the qualification of equipment is of prime importance. The subsea OIWM will be put through similar qualification tests to other KOP subsea electronics. The tests will cover operation at low and high temperature extremes, thermal cycling, storage at low and high temperature extremes, operation during various vibration modes, shock testing, pressure and hyperbaric testing. The subsea OIWM interfaces to control systems will also be verified and the OIWM will be qualified by testing against relevant EMC directives.

Duty qualification
Following completion of the environmental qualification, the subsea OIWM will be put through a qualification process to ensure that the instrument's capability to measure oil in water concentration has not been diminished by any design changes. The qualification will characterise the OIWM responses to temperature, pressure and produced water salinity and ensure these match with previous versions of the instrument. Following completion of the characterisation the OIWM will be qualified for stability and repeatability. The final qualification test will be a flow test in oily water to define the measurement performance of the subsea OIWM.