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GAMMA RAY <br />cu <br />1900 r-r- <br />2000 <br />2100 <br />2200 <br />2300 <br /> <br />NEUTRON CALIPER <br />Eigure 1J <br />well and indicates a hole in the casing fxom 2, 025 to 2, 028 feet. Another hole exists from Z, 116 <br />to 2, 120 feet. An examination of the lengths of the joins in which the holes exist indicates cor- <br />rosive action rather than parting of the pipe. <br />An unusual condition that existed in a producing well is displayed in Fig. 14. The well had <br />been a producer since its original completion date. Ten and three fourth-inch casing was the long <br />string with six-inch transit used as a liner. The production had declined remarkedly at the time <br />of logging Curves # 1 and # 2, a Gamma Ray-Neutron Log. Curve # 3, a Caliper Log, recorded on <br />the same [rip to the well indicated a sizeable build-up inside [he liner and casing. An inspection <br />at the surface indicated a gyp forming on the casing. Immediately, the well was conver[ed to an <br />injection well. The injection rate s[arted slow and gradually rose to the expected rate. Ten <br />months after injection was started, Curve # 4 was recorded with [he Caliper indica[ing well bore <br />diameters comparable to nominal casing diameters. <br />Figure 15 is a sketch of a Cemen[ Bond tool in a cased well bore. The Cement Bond tool is <br />an acoustic device utilizing a single [ransmi[ter and receiver. The spacing between the [ransmit- <br />ter and receiver is normally six fee[. The tool is centralized in [he casing and utilizes the fluid <br />in the well bore to [ransfer [he acoustic signal to the pipe and the medium beyond the pipe. A <br />borehole gain in the receiver section that may be controlled at the surface is most essential. At <br />the surface an ocilloscope is utilized to monitor the recorded signal. An electronic gate in the <br />surface equipment is utilized. The width and position of the gate can be varied in time. The am- <br />pli[ude of the received signal is recorded as dte amplitude log. The transit [ime for arrival of the <br />firs[ event is recorded as the [ransit time curve. <br />65 <br />