Bottom Hole Flow Surveys for Determination of Fluid and Gas Movements in Wells

The need for instruments to measure the movement of fluids and gas in wellshas been recognized by engineers for many years. Information regarding flow inthe producing interval has a direct bearing on completion practices in newwells and also provides information on the production characteristics of thewell. Many hours of engineering time are spent in planning and completing wellsbut knowledge as to whether or not the original planning has produced thedesired results has not always been complete. Many questions such as thefollowing often arise: Why is it that two wells are completed under supposedlyidentical conditions, yet one well is a good one and the other is a poor one. Are the sands that look the best on the electric log contributing to theproduction? These and many other conditions in the producing well need to beunderstood in order to develop more efficient production practices and toimprove on methods of completing new wells. It is the purpose of this paper tobriefly describe one type of instrument, outline the methods of running theequipment and show the results of surveys made under various conditions. Withan understanding of the use of this type of survey its importance can beevaluated in relation to the problems encountered by the operator. Description of Instrument The instrument is a velocity recorder employing a clock-controlled 16mm filmfor recording the rpm of an extremely sensitive rotor which is rotated by theflow of fluids or gas in a well. The helical-vaned rotor and shaft, weighingone-half of one ounce are an integral unit exposed to the well fluids and arethe only moving parts not enclosed in the fluid-tight housing. No packing orfluid seal of these parts is necessary and the shaft is mounted top and bottomon special jeweled bearings. Fig. A is the lower part of the instrument showingrotor and shaft with the protecting housing sleeve removed. The rpm of therotor is recorded on the moving film by a combination electrical and opticalsystem. The record is a series of dashes on the film, each dash and spacerepresenting twenty (20) revolutions of the rotor. T.P. 2644