This group of products is used on the leading edge of a casing tube string to advance it through the overburden layer and into the bedrock by means of rotational drilling. Depending on the range of application, the cutting media on the core bit may take the form of synthetic diamond, tungsten-carbide particles or tungsten-carbide elements.
Diamond Impregnated Casing Shoes
The diamond impregnated casing shoe is the most commonly used as it has the widest range of application and is generally the most efficient tool for advancing casing through overburden layers. Dimatec manufactures two types of diamond impregnated casing shoes that may be used with all sizes of standard casing tubes.
In addition to casing shoes, Dimatec also manufactures diamond impregnated rod shoes. In terms of design, rod shoes are very similar to casing shoes and differ only in their thread connections. Rod shoes are used where wireline drill rods are used as casing tubes.
The basic construction of these casing shoes and rod shoes features a sintered powdered metal crown that is fused to a steel tool body or shank. The powdered metal crown is composed of two layers: the “matrix” layer which cuts the overburden and the “backing” layer which connects the matrix layer to the steel tool body and serves to support the gauge diameter protection hard materials.
D-Series Casing Shoes / D-Series Rod Shoes
This economical diamond impregnated casing shoe / rod shoe is available for use with all standard casing tube sizes and a limited number of wireline drill rod sizes. The Dimatec ‘D-Series’ casing shoe is intended for use in applications where the casing tubes are to be permanently left in the drill hole.
Dimatec ‘D-Series’ casing shoes and rod shoes are supplied with a:
- Flat-Face (Style ‘F’) crown profile.
- Regular (Style ‘W’) waterway configuration.
- 0.12 inch (3 mm) diamond impregnation depth.
The matrix layer on all sizes of Dimatec ‘D-Series’ diamond impregnated casing shoes contains a mixture of mesh-size synthetic and natural diamond crystals that are uniformly distributed and embedded in a powdered metal bond.
Unlike the matrix layer, the backing layer does not contain diamond crystals distributed throughout its volume. The backing layer is also composed of a powdered metal bond material and has good wear resistance properties. The exposed outside and inside gauge diameter surfaces of this layer are set with a combination of thermally stable polycrystalline synthetic diamond elements and tungsten-carbide wear pads. These gauge setting materials assist in maintaining the critical gauge diameters throughout the life of the shoe.
Super Duty Casing Shoes / Super Duty Rod Shoes
Dimatec ‘Super Duty’ diamond impregnated casing shoes and rod shoes are available for use with all standard DCDMA casing tube sizes and a limited number of wireline drill rod sizes. The Dimatec ‘Super Duty’ casing shoe is manufactured with a more aggressive matrix layer than the ‘D-Series’ type and is intended for use in thick overburden layers that may contain boulders.
Dimatec ‘Super Duty’ casing shoes and rod shoes are supplied with a:
- Modified V-Ring (Style ‘VC’) crown profile.
- Regular (Style ‘W’) waterway configuration.
- 0.24 inch (6mm) diamond impregnation depth.
The matrix layer on all sizes of Dimatec ‘Super Duty’ diamond impregnated casing shoes contains mesh-size synthetic diamond crystals that are uniformly distributed and embedded in a powdered metal bond.
Unlike the matrix layer, the backing layer does not contain diamond crystals distributed throughout its volume. The backing layer is also composed of a powdered metal bond material and has good wear resistance properties. The exposed outside and inside gauge diameter surfaces of this layer are set with a combination of thermally stable polycrystalline synthetic diamond elements and tungsten-carbide wear pads. This gauge setting is considerably more dense than the setting on a comparably sized ‘D-Series’ casing shoe. These gauge setting materials assist in maintaining the critical gauge diameters throughout the life of the shoe.
Although hard-metal strips that are used to armor coat the steel tool body are normally not provided on Dimatec ‘Super Duty’ casing shoes and rod shoes, this option is available at an additional cost and is recommended when drilling through extremely abrasive and unconsolidated conditions.
Tungsten-Carbide Casing Shoes
This type of casing shoe uses seismic grade tungsten-carbide as the cutting media. Tungsten-carbide does not possess the hardness of diamond and as such has a limited range of application as a drill tool cutting media. Tungsten-carbide casing shoes are however a very cost effective means of drilling through softer unconsolidated formations. There are two types of tungsten-carbide casing shoes produced by Dimatec: the “carbide-chip” and the “saw-tooth” types.
In addition to casing shoes, Dimatec also manufactures tungsten-carbide rod shoes. In terms of design, rod shoes are very similar to casing shoes and differ only in their thread connections. Rod shoes are used where wireline drill rods are used as casing tubes.
Saw-Tooth Tungsten-Carbide Casing Shoes and Rod Shoes
These tools are set with large, rectangular-shaped tungsten-carbide elements that are physically embedded into the crown of the tool. The bit face has an aggressive saw-tooth pattern with integral canal type waterways. The bit crown itself is composed of a tough, wear resistant metal-bond matrix material. The gauge diameters of the tool are also heavily set with tungsten-carbide wear pads.
The application of this type of tool is primarily in geotechnical soil investigation or for advancing casing tubes through overburden layers that are composed mainly of clay, sand, gypsum or soft shale
Carbide-Chip Casing Shoes and Rod Shoes
The cutting media used in this type of casing shoe are crushed tungsten-carbide chips that are suspended in a metallic alloy that is fused to the steel body of the tool. Typically, these tungsten-carbide chips have a granular size 0.08 to 0.20 inch (2 to 5mm) and have a totally random orientation within the bit crown. The face profile is somewhat irregular and the waterways are of the standard canal type (Style “W”) design.
This type of casing shoe crown has considerably more cutting edges than the “saw-tooth” variety and as such has a wider range of application that includes slightly harder sedimentary formations.
Carbide-chip casing shoes are similar to impregnated diamond casing shoes in that the bit crown is composed of several layers of cutting media. The tool face regenerates itself with new cutting edges by wearing away the metallic alloy during operation to continually expose new layers of carbide-chips until the tool crown is consumed.
