X-ray or gamma ray systems or devices – Specific application – Absorption
Patent
1997-06-10
1998-10-13
Porta, David P.
X-ray or gamma ray systems or devices
Specific application
Absorption
378 51, G01N 2312
Patent
active
058223908
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a mixer and apparatus for analysing fluid flow.
One situation in which fluid flow analysis is important is in the production of oil from an oil well, or group of oil wells. Oil is commonly found mixed with water and gas thus providing a three phase fluid flow. Clearly, it is important to be able to determine how much of the fluid flow is constituted by each of the three phases.
Known apparatus for phase fraction analysis comprises two gamma radiation sources with associated detectors, which are spaced apart along a pipe in the flow direction. The sources emit radiation at different energies. The signals from the detectors are proportional to the gamma radiation received and hence indicate the radiation absorption from the flow. This information enables the phase fractions of the flow to be determined. The phase fractions of the flow may vary widely with time as the flow passes the detectors due the occurrence of slug flow, for example, and the analysis is consequently subject to inaccuracy, particularly as the relationship between radiation absorption and the amount of fluid intercepting the beam is exponential.
According to the invention there is provided apparatus for analysing fluid flow in a pipe comprising at least one radiation source to direct radiation through the flow, and at least one radiation detector positioned to receive from the source or sources radiation which has passed through the flow, the source or sources emitting radiation at least at two different energies, the or each detector providing a signal to processing means, the processing means being arranged to process the signal to provide a series of chronological values and to group the values by magnitude for analysis by analysis means.
As the signal becomes a series of values which are grouped, the analysis means can conduct a more sophisticated analysis than simple averaging and a more accurate analysis can be conducted. Preferably, the analysis means is arranged to determine the phase fractions in the flow. Alternatively, or in addition, the analysis means may be arranged to determine the type of flow e.g. slug flow or stratified flow. In addition the analysis of the signals by grouping provides information on the variation of composition of the mixture with time. For example in slug flow the oil/water ratios in the slug and in the thin film between slugs can be individually determined.
Preferably, radiation from the or each source will be measured over a series of short time intervals. In one embodiment, a single detector is provided. In that case, two sources may be provided, each emitting radiation at a different energy. In the prior system, necessary separation of the two sources lead to errors as the radiation beams did not "see" the same section of flow. Because of the processing and analysis which is carried out by the apparatus of the invention, this necessary separation is possible without incurring errors.
As an alternative to two sources, a single source can be used which is arranged to emit radiation of at least two different energies, e.g. a caesium source emitting radiation at 32 keV and 661 kev.
The apparatus is principally intended for use with three phase flow and so preferably radiation at only two different energies is emitted by the source or sources.
The radiation may be X-ray and/or gamma radiation.
The apparatus may include a mixer and means for sensing pressure drop across the mixer. This enables velocity calculations to be carried out when combined with means for sensing liquid hold-up. The sensing means are preferably associated with the analysis means which is arranged to determine flow rate. The means for sensing the liquid hold-up may comprise at least one radiation source to direct radiation through the flow to at least one radiation detector positioned to receive radiation which has passed through the flow from the or each source.
In one embodiment, the apparatus includes only two sources and only two detectors and the analysis means is arranged to determine both phase fractio
REFERENCES:
patent: 4228353 (1980-10-01), Johnson
patent: 5689540 (1997-11-01), Stephenson et al.
Harrison Paul Stephen
Hewitt Geoffrey Frederick
Mark Philip Antony
Parry Susan Joan
Shires George Lister
I.C. Consultants Limited
Porta David P.
LandOfFree
Apparatus for analyzing fluid flow does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for analyzing fluid flow, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for analyzing fluid flow will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-321474