EESIFLO Water Cut Meters

Producers normally want to supply oil instead of water to their clients.  Oil containing water has a lower BTU value and also water can cause corrosion in pipelines. Refineries are always looking for ways to avoid expensive downtime and water is found commonly in hydrocarbon production. Water can cause difficulties in bother upstream and downstream processes. On the upstream side, three phases separators and two phase separators might be a commonly used to effect separation of product but when the pipeline contains oil that has amounts of  water still remaining, watercut meter might be used to determine the condition of the oil in the pipeline.

Fig 1.1 High Pressure Intrinsically safe watercut meter in Duplex Stainless steel

BS&W  and LACT UNITS During certain custody transfer operations there can be a need to know the amount of water that is present in the crude.  A common solution is the use of  LACT units  (lease activated custody transfer). A typical LACT Unit incorporates a BS&W (basic sediment and water) Monitor which is a water cut meter but the purpose of this meter is to measure the water content in the oil when it reaches a set point. When the set point is reached a valve is triggered and the product is diverted. The EASZ-1 watercut meter is available in both low and high cut models. It is important in these applications that the meter employed must be able to determine low contents of water e.g below 1%.  The EASZ-1 is an excellent device for these applications and is an intrinsically safe device certified to ATEX, IECEX, CSA and Russian GOST standards. Over the years, several methods have been used measure water/oil mixtures and the most common method is the direct  measurement of the the dielectric constant of the mixture of oil and water. An equation is applied  to determine the composition.  It is a known fact that water is a polar molecule and has a dielectric constant of around 80, while oil is a non-polar molecule and has a dielectric constant of around 2. An increase in a  small amount of water in  oil immediately changes the dielectric constant of the mixture dramatically. With new and improved technology including the advances in circuit stability EESIFLO International has continually developed its range of watercut meters to measure water/oil fractions in low and high ranges with unsurpassed accuracy and stability. The proof of a meter’s ability to measure accurately with repeatable results is seen when a producer is able to correlate representative samples with the current online measurement.

MIXING AND REPRESENTATIVE SAMPLES

Water in hydrocarbons has always been something to consider carefully in the oil industry and a common problem is water in crude oil. How it is measured or reported can affect either the buyer or seller financially. This may include:

1. Custody Transfer
2. Allocation
3. Plant Balance (refinery input)
4. Product Quality
5. Sediment & Water
6. Shrinkage (entrained gas)
7. API gravity
8. Contractual requirements

A barrel of water, can cost considerably more than a barrel of oil. Someone has to pay for the oil, pay for the water, pay for the disposal of water and pay for the process contamination. Everyone is looking for a quick fix and even today we find contracts written around spot sampling which can be completely unreliable if the sample is non representative of the liquids in the process stream. The lab results are thus invalid and the frustration simply increases because the measurements unfairly affect someone’s wallet. Could this be your wallet?

Fig. 1.0 Separation occurs in oil/water processes and spot sampling using the above method misses “bottom” water.

Laboratory analyses are generally accurate but are quite useless if the sample being analyzed is not representative of the TOTAL FLUID FLOW

The same applies online. Fig 1.1 World class watercut meter measuring a non-representative distribution of water and oil. Inevitable and problematic watercut measurements ,arguments, doubts and wasted time and money.

Fig 1.1

Additionally we have problematic calibration if watercut meters are calibrated to lab results from non representative spot sampling. Spending the money on a highly accurate instrument that is not sensing at a point where we have a homogeneous mixture is an exercise in futility.

The problem becomes chronic as oil wells depressurize and watercut increases to the point when there is more water than oil being produced . In small pipes the chances of getting proper mixing in a higher watercut situation is doubtful and in large (greater than 6 inches) pipes it is a pipe dream. Honest field operators will be familiar with the problems of laboratory prepared spot samples for calibration never tallying with the reported watercut .

The only known solution is to mix, so that our sampling or watercut instruments are gathering samples or data in a volume area where sample is representative and homogeneous! Whether we are taking spot samples, grab sampling or installing watercut meters, the same will apply if we have an uneven or unpredictable water distribution in the crude oil stream. Manufacturers of static mixers have proved this fact time and time again over the years.

There is adequate data to show that mixing should not be considered an option since API chapter 8 stipulates a need for mixing in the implementation of crude oil grab samplers. If this is true for composite sampling, then the same logic would normally apply to representative online watercut measurements.

EESIFLO manufactures the EASZ-1 loop powered watercut monitors and inline static mixers and complete MBW systems which can incorporate any measuring instrument that we manufacture or the measurement instruments of your choice .The complete spool pieces can be fabricated and shipped and installed as a one piece system.

MBW systems are manufactured or fabricated in EESIFLO’s Singapore fabrication facility but can be supplied as a complete package through our global network .For more information, send an email with your basic requirements to Dave Hughes EESIFLO International Pte Ltd Oil and Gas Division Manager 60 Kaki Bukit Place #02-19 Eunos TechPark Singapore, SG 415979 Telephone: +65-6748 6911 Fax: +65-6748 6912 Email dave@eesiflo.com