Casing and liner drilling bits and reamers

A casing bit reamer for drilling a casing section into a subterranean formation by enlarging a borehole, comprising:

• a pilot section, at least a portion thereof configured to be drilled therethrough by way of a drilling tool having a drilling profile defined by a drilled surface that would be formed by a full rotation of the drilling tool about a drilling axis, the pilot section having an inner profile, an outer profile, a nose portion, and a first cutting structure;
• wherein the first cutting structure comprises:
• a plurality of generally radially extending blades disposed on the nose portion, wherein at least one of the plurality of blades carries a plurality of cutting elements;
• and
• at least one gage section, the at least one gage section defining a pilot gage diameter;
• wherein each of the plurality of cutting elements contains an amount of abrasive material;
• wherein a first portion of the plurality of cutting elements is disposed generally within the at least a portion of the pilot section that is configured to be drilled through;
• wherein a second portion of the plurality of cutting elements is disposed generally peripheral to the at least a portion of the pilot section that is configured to be drilled through;
• wherein a majority of the cutting elements of the first portion is configured differently than a majority of the cutting elements of the second portion;
• and
• wherein the amount of abrasive material contained by each of the cutting elements of the first portion of the plurality of cutting elements is less than the amount of abrasive material contained by each of the cutting elements of the second portion of the plurality of cutting elements;
• a reamer section longitudinally adjacent the pilot section comprising a tubular body including a second cutting structure thereon;
• wherein the second cutting structure comprises:
• a plurality of generally radially extending blades disposed on the tubular body, wherein at least one of the plurality of blades of the second cutting structure carries one or more cutting elements;
• and
• at least one gage section, the at least one gage section of the second cutting structure extending longitudinally from the reamer section and defining a reaming diameter that is larger than the pilot gage diameter.

A casing bit reamer for drilling a casing section into a subterranean formation by enlarging a borehole, comprising:

• a pilot section, at least a portion thereof configured to be drilled therethrough by way of a drilling tool having a drilling profile defined by a drilled surface that would be formed by a full rotation of the drilling tool about a drilling axis, the pilot section having an inner profile, an outer profile, a nose portion, and a first cutting structure;
• wherein the first cutting structure comprises:
• a plurality of generally radially extending blades disposed on the nose portion, wherein at least one of the plurality of blades carries a plurality of cutting elements;
• and
• at least one gage section, the at least one gage section defining a pilot gage diameter;
• wherein a first portion of the plurality of cutting elements is disposed generally within the at least a portion of the pilot section that is configured to be drilled through;
• wherein a second portion of the plurality of cutting elements is disposed generally peripheral to the at least a portion of the pilot section that is configured to be drilled through;
• wherein a majority of the cutting elements of the first portion is configured differently than a majority of the cutting elements of the second portion;
• wherein at least one of the cutting elements generally within the at least a portion of the pilot section that is configured to be drilled through comprises a first grade of cutting element related to at least one inherent quality related to wear characteristics, and at least one of the cutting elements generally peripheral to the at least a portion of the pilot section that is configured to be drilled through comprises a second grade of cutting element related to at least one inherent quality related to wear characteristics, wherein the at least one inherent quality of the second grade of cutting element is generally different than the at least one inherent quality of the first grade of cutting element;
• wherein the at least one inherent quality related to wear characteristics of the first grade of cutting element is generally inferior to the at least one inherent quality related to wear characteristics of the second grade of cutting element;
• a reamer section longitudinally adjacent the pilot section comprising a tubular body including a second cutting structure thereon;
• wherein the second cutting structure comprises:
• a plurality of generally radially extending blades disposed on the tubular body, wherein at least one of the plurality of blades of the second cutting structure carries one or more cutting elements;
• and
• at least one gage section, the at least one gage section of the second cutting structure extending longitudinally from the reamer section and defining a reaming diameter that is larger than the pilot gage diameter.

A casing bit reamer for drilling a casing section into a subterranean formation by enlarging a borehole, comprising:

• a pilot section having an inner profile, an outer profile, and a nose portion, the pilot section having a first cutting structure thereon;
• wherein the first cutting structure comprises:
• a plurality of generally radially extending blades disposed on the nose portion, wherein at least one of the plurality of blades carries one or more cutting elements, at least one rotationally trailing groove formed in at least one of the plurality of blades;
• and
• at least one gage section, the at least one gage section defining a pilot gage diameter;
• a reamer section longitudinally adjacent the pilot section comprising a tubular body including a second cutting structure thereon;
• wherein the second cutting structure comprises:
• a plurality of generally radially extending blades disposed on the tubular body, wherein at least one of the plurality of blades of the second cutting structure carries one or more cutting elements;
• and
• at least one gage section, the at least one gage section of the second cutting structure extending longitudinally from the reamer section and defining a reaming diameter that is larger than the pilot gage diameter.