Measurement of fluid flow,especially for small values of flow rate,is important and,at the same time,a difficult task [1,8-11].The need for reliable measurement of this parameter is especially important for operating well logging.There are many flow measurement methods that are based on measuring the flow rate when the cross-sectional area is known.A wide-spread thermo-anemometer method was obtained in the study of producing wells.Its operation is based on the dependence of the body heat transfer on the flow velocity of its cooling fluid flow [3-5].Thermal anemometers are used to detect inflow and uptake intervals; determination of leakage of the column under low-rate conditions,when mechanical flow-meter is ineffective.The sensors are reliable,compact,have low inertness.But with all the advantages,thermal anemometers have their own limitations: 1.Only the first inflow interval is well defined,then the sensitivity decreases sharply; 2.The change in ambient temperature can be perceived as a change in the composition or velocity of the fluid,which reduces the efficiency of determining the radial flow; 3.The instrument's readings are strongly influenced by the axial flow of the liquid In this regard,the development of more effective thermal anemometer sensor remains an urgent task.In this case,the development of an azimuthally-distributed thermal anemometer of indirect heating is one of the possible ways [6,7].The main idea of the method The essence of the idea of an azimuthally distributed thermal anemometer is as follows: The thermoanemometer has not one thermosensitive element,but four,which are located symmetrically and evenly in one plane of the cross section of the body(Figure 1(B)).Let's assume that the thermal anemometer(figure 1(A))is in the production well.Accordingly,there is an axial flow(ascending),and also a radial flow(inflow of liquid).The sensor goes down to the required depth,and after turning on the heater it starts to rise at a constant speed.In the presence of an upward flow of liquid Q1(Figure 1),the temperature difference of the outer surface of the sensor body,registered by the temperature-sensitive elements 1 and 2,3 and 4,will be zero.In this case,the electronic information processing device will indicate the absence of a lateral fluid flow.If,in addition to the flow Q1,there is also a flow of fluid Q2,directed perpendicular to the sensor housing,the cylindrical surface from the side of the oncoming stream Q2 will be cooled more intensively,due to which its temperature will be lower than the surface temperature of the cylinder on the diametrically opposite side.This temperature difference is recorded by the corresponding thermo-sensitive elements,and the electronic information processing device will indicate the presence and direction of the lateral fluid flow.The greater the number of pairs of thermosensitive elements,the more certain it is possible to register the presence of a side stream,with the other things being equal(the diameter and thickness of the shell walls,the length of the sensor working surface)and more accurately determine the vector of its direction.It is possible to improve the accuracy of determining the direction of the lateral fluid flow,carrying out by means of an electronic device the processing of information from thermocouples according to a given algorithm.
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