GB1237050A - Method of investigating well blast conditions - Google Patents

Abstract

1,237,050. Acoustic inspection devices. MOBIL OIL CORP. 4 July, 1969 [5 July, 1968], No. 33862/69. Heading H4D. A method of investigating a cased well including a tubing string 23 (Fig. 1) extending through a producing zone 14 comprises positioning a sound detector 30 inside the string adjacent the zone and monitoring the sound created by the impingement of the well production stream from the producing zone on the exterior of the string. Hence the possible clogging of perforations 28, resulting in excessive flow velocity of the well stream through unclogged perforations and consequent abrasion of the tubing string, can be detected. In the dual completion well shown, two production zones 14, 16 are packed-off at 24, 26 and feed tubing strings 22, 23 independently. Zone 16 is shut off during the investigation, while detector 30 on support/conductor line 32 is moved in steps or continuously along string 23 and detected signals are fed to surface logging equipment. At the surface the signals are amplified at 40 (Fig. 2), rectified at 42 and fed to chart recorder 44. Sheave 33 provides depth synchronization of recorder 44 and operates depth indicator 52. An adjustable frequency-filter 48 may be used to eliminate irrelevant noise signals and its effect can be monitored on oscilloscope 51 whose trace may be photographed. In various modifications detector 30 output may be displayed on a meter whose readings are recorded as a function of depth, fed to earphones, or magnetically recorded for later playback and visual readout or for frequency analysis or signal enhancement on a computer, and the sound parameter logged may be the peak amplitude, the average amplitude or the root mean square amplitude. Detector 30 may comprise a radially-sensitive lead zirconate cylindrical transducer and may include the rectifier 42.