Abstract: A technique facilitates conveyance of equipment along a wellbore or other tubular structure. A tractor is provided with a plurality of wheels oriented to engage a surrounding wall. Rotation of the wheels drives the tractor and causes longitudinal movement of the tractor with respect to the surrounding wall via a tangential force created between each wheel and the surrounding wall. Each wheel comprises teeth having a wheel tooth geometry which enhances cooperation with the surrounding wall. For example, the wheel tooth geometry may be designed to cooperate with the tangential force to push debris out of the teeth of each wheel during rotation of the wheel along the surrounding wall. In some applications, the wheel tooth geometry is designed to present a plurality of raised, rounded surfaces which engage the surrounding wall with a low stress impact.

Abstract: A technique facilitates conveyance of equipment along a wellbore or other tubular structure. A tractor is provided with a plurality of wheels oriented to engage a surrounding wall. Rotation of the wheels drives the tractor and causes longitudinal movement of the tractor with respect to the surrounding wall via a tangential force created between each wheel and the surrounding wall. Each wheel comprises teeth having a wheel tooth geometry which enhances cooperation with the surrounding wall. For example, the wheel tooth geometry may be designed to cooperate with the tangential force to push debris out of the teeth of each wheel during rotation of the wheel along the surrounding wall. In some applications, the wheel tooth geometry is designed to present a plurality of raised, rounded surfaces which engage the surrounding wall with a low stress impact.

Abstract: A seismic sensor contains a geophone (4) disposed within a housing (12). The sensor is also provided with locking means (14, 19, 21) that can either lock the geophone 4 relative to the housing, or can allow the geophone to rotate within the housing. The geophone (4) is enclosed in a casing (1) which is so constructed that the overall mass distribution of the casing and geophone is uneven. The casing and geophone assembly thus adopts a preferred orientation when the sensor is unlocked. A liquid can be disposed within the housing, so that the casing (1) and geophone (4) can float when the sensor is unlocked.

Abstract: A seismic sensor contains a geophone (4) disposed within a housing (12). The sensor is also provided with locking means (14, 19, 21) that can either lock the geophone 4 relative to the housing, or can allow the geophone to rotate within the housing.

Abstract: A method for land seismic data acquisition is provided, together with a seismic cable and a cable spool vehicle for use in the method. In performing the method, the cable spool vehicle mechanically deploys seismic cable with attached sensors according to a desired geophysical spread and at a rate dependent upon the speed of movement of the vehicle substantially without tension in the cable. The cable spool vehicle also allows mechanical pick-up of the seismic cable together with the sensors after the seismic data acquisition.