WEIGHT DROP SEIS SOURCE TESTS IN WELLS

Institut Francaise du Petrole and other sponsors have developed and field tested a weight drop source for well seismic operations. The source is designated Clubs, for clamped underground borehole source. It is designed for well seismic application and is particularly useful in crosshole seismic surveying. The sponsors used the device in two oil wells in France, performing more than 1,600 shots in 30 hr without failure. The source was lowered in a 7 in. cased, poorly cemented borehole at

March 25, 1991

2 min read

Institut Francaise du Petrole and other sponsors have developed and field tested a weight drop source for well seismic operations.

The source is designated Clubs, for clamped underground borehole source. It is designed for well seismic application and is particularly useful in crosshole seismic surveying.

The sponsors used the device in two oil wells in France, performing more than 1,600 shots in 30 hr without failure. The source was lowered in a 7 in. cased, poorly cemented borehole at depths of 4,2605,750 ft.

It produced P and S waves that were recorded by a four level, three component Multilock geophone system 1, 1 501,960 ft from the source (OGJ, Jan. 14, p. 73). The device created consistent reflected P and S wave fields.

IFP developed the instrument as a result of a project supported by the European Economic Community, the French government, Compagnie Generale de Geophysique, Gaz de France, and Ste. Nationale Elf Aquitaine.

The Clubs source, linked with surface equipment via a conventional seven conductor logging cable, can work in 7-8.5 in. boreholes, It emits a broad spectrum of 10-400 hz and is harmless to casing and cement.

The source, which fires at the rate of two shots-min, is self-contained and therefore capable of an unlimited number of shots at one depth and in the same borehole.

The depth limit is about 6,500 ft, and the device has been used trouble free to 5,750 ft.

Comprising the source are an electric motor, hydraulic pump and winch, and a clamping module equipped with six coupling pads.