A system for improving drill bit performance, having processors and memory storing instructions to obtain a wear report for a drill bit, wherein the wear report includes wear characteristics of the drill bit and drill operating parameters under which the drill bit was used; compare the wear characteristics of the drill bit to a threshold for acceptable drill bit wear; and adjust drill operating parameters based on the wear characteristics of the drill bit. The instructions to obtain the wear report for the drill bit include instructions to analyze images of the drill bit to identify wear characteristics; identify wear patterns based on the wear characteristics of the drill bit; identify probable drilling conditions based on the wear patterns; and generate the wear report for the drill bit based on the images of the drill bit, the wear characteristics of the drill bit, and the probable drilling conditions.

Downhole monitoring systems are described. The systems include a downhole string disposed in a borehole, the string having a downhole tool and the borehole has fluid therein. A sacrificial electrical sensor element is arranged in or on the string. The sacrificial electrical sensor element includes magnetic material at least partially exposed to the fluid and at least one coil arranged in magnetic communication with the magnetic material. A controller is configured to provide an electrical current into the coil, measure an electrical property of the coil that is based on the magnetic material in magnetic communication with the coil, and determine a wear state of the downhole tool based on the measured electrical property.

Downhole monitoring systems are described. The systems include a downhole string disposed in a borehole, the string having a downhole tool and the borehole has fluid therein. A sacrificial electrical sensor element is arranged in or on the string. The sacrificial electrical sensor element includes magnetic material at least partially exposed to the fluid and at least one coil arranged in magnetic communication with the magnetic material. A controller is configured to provide an electrical current into the coil, measure an electrical property of the coil that is based on the magnetic material in magnetic communication with the coil, and determine a wear state of the downhole tool based on the measured electrical property.

A sensor element for a cutting tool (100) has a hard portion (110) having a sensing surface (112), first and second electrodes (120, 130), first and second sets of thermocouple wires (122, 132) and an electrically insulating portion. The first and second electrodes (120, 130) are arranged to allow electric current to flow when the sensing surface (112) contacts external material in response to the cutting tool engaging the external material. A first thermocouple junction (124) is operable to indicate a temperature of the first electrode and a second thermocouple junction (134) is operable to measure temperature of the second electrode.

A sensor element for a cutting tool (100) has a hard portion (110) having a sensing surface (112), first and second electrodes (120, 130), first and second sets of thermocouple wires (122, 132) and an electrically insulating portion. The first and second electrodes (120, 130) are arranged to allow electric current to flow when the sensing surface (112) contacts external material in response to the cutting tool engaging the external material. A first thermocouple junction (124) is operable to indicate a temperature of the first electrode and a second thermocouple junction (134) is operable to measure temperature of the second electrode.

Drill bit wear can be quantified through an analysis of chemical reactions that occur during drilling. A detector measures the molar composition of a dissolved gas sample. From the molar composition, the moles of hydrogen, ethylene, and propylene in the dissolved gas sample are determined. A thermal cracking reaction and a thermal decomposition reaction determine moles of hydrogen produced during drill bit wear based on the moles of ethylene and propylene. The moles of hydrogen produced is subtracted from the total moles of hydrogen to determine moles of hydrogen produced by metal oxidation. A metal-water reaction determines the moles of metal that have been oxidized. This can be converted into mass or volume of metal loss to quantify drill bit wear.

Drill bit wear can be quantified through an analysis of chemical reactions that occur during drilling. A detector measures the molar composition of a dissolved gas sample. From the molar composition, the moles of hydrogen, ethylene, and propylene in the dissolved gas sample are determined. A thermal cracking reaction and a thermal decomposition reaction determine moles of hydrogen produced during drill bit wear based on the moles of ethylene and propylene. The moles of hydrogen produced is subtracted from the total moles of hydrogen to determine moles of hydrogen produced by metal oxidation. A metal-water reaction determines the moles of metal that have been oxidized. This can be converted into mass or volume of metal loss to quantify drill bit wear.

The invention discloses a mechanics calculation method of drill bit tooth considering rock dynamic strength and mixed crushing mode, including: Step S1: selecting a target drill bit tooth and a target rock, and determining a type of target drill bit tooth, a geometry of the target drill bit tooth, a rock type and rock parameters of the target rock; Step S2: calculating a horizontal cutting force of the target drill bit tooth according to a horizontal cutting mechanics calculation method of drill bit tooth; Step S3: calculating a vertical penetration force of the target drill bit tooth according to a vertical penetration mechanics calculation method of drill bit tooth; Step S4: calculating a resultant force experienced by the target drill bit tooth according to a resultant force calculation method of drill bit tooth. The invention provides a calculation method for accurately obtaining drill bit tooth mechanics under different working conditions.

The invention discloses a mechanics calculation method of drill bit tooth considering rock dynamic strength and mixed crushing mode, including: Step S1: selecting a target drill bit tooth and a target rock, and determining a type of target drill bit tooth, a geometry of the target drill bit tooth, a rock type and rock parameters of the target rock; Step S2: calculating a horizontal cutting force of the target drill bit tooth according to a horizontal cutting mechanics calculation method of drill bit tooth; Step S3: calculating a vertical penetration force of the target drill bit tooth according to a vertical penetration mechanics calculation method of drill bit tooth; Step S4: calculating a resultant force experienced by the target drill bit tooth according to a resultant force calculation method of drill bit tooth. The invention provides a calculation method for accurately obtaining drill bit tooth mechanics under different working conditions.

Various embodiments include apparatus and methods to estimate properties of rock, drill bit, or a combination thereof associated with a drilling operation. The properties can include, but are not limited to, rock chip size, drill bit dullness, drilling efficiency, or a combination selected from rock chip size, drill bit dullness, and drilling efficiency. The estimate may be accomplished from correlating detected acoustic emission with detected electromagnetic emissions. In various embodiments, formation brittleness may be determined. The various estimates may be used to direct a drilling operation. Additional apparatus, systems, and methods are disclosed.