Abstract: The present invention provides a bottom-hole impact-rotation stepping combined unloading rock-breaking efficient drilling system, including a housing, a drive assembly, a universal joint, a transmission shaft, a rotational impact assembly, and a drill bit; the transmission shaft is connected with the housing; the rotational impact assembly includes a rotational transmission assembly for conveying a rotational power to the drill bit and an impact assembly for providing a high frequency axial impact power to the drill bit; when the rotational transmission assembly rotates along with the transmission shaft, the impact assembly applies a high frequency impact force along a drilling axial direction to the rotational transmission assembly; an annular drill bit is disposed at an outer end of a drill bit body of the drill bit; a central drill bit is slidably disposed on an inner ring end surface of the annular drill bit; an inwardly-recessed cylindrical region is formed between a head end of the annular drill bit and

Abstract: A risk assessment-based design method for a deep complex formation wellbore structure includes: (1) preliminarily determining casing layers and setting depths; (2) calculating to obtain the risk coefficients of each layer of casing; (3) analyzing and coordinating, according to the principle that a shallow casing shares more risks and a deep casing shares less risks, the risks of each layer of casing: determining whether the risk coefficients of each layer of casing are greater than a safety threshold value K; checking the setting depth: if the safety coefficient of an ith-layer casing satisfies RNi>K, selecting a casing layer with the minimum safety coefficient from upper casing layers, and deepening the setting depth h of the casing layer; and (4) repeating the steps (2) to (3) until the casing risk coefficients of each layer of casing are less than the safety threshold value K.

Abstract: A drill bit performs pilot rock-breaking using an outer annular drill bit and breaks a central rock pillar using a central drill bit mounted in the middle of the annular drill bit and located inside a drill bit body to induce unloading of a bottom hole stress. A method mixes rock debris produced by rock breaking of the central drill bit as abrasive with the drilling fluid flowing into the entire drill bit as abrasive jet liquid phase to form an abrasive jet. The method includes obtaining an annular borehole by braking, and breaking the rock pillar at the inner side of the annular borehole to induce unloading of the bottom hole stress, mixing the rock debris produced by breaking the rock pillar at the inner side of the annular borehole as abrasive with the drilling fluid entering the drill bit to form an abrasive jet.

Abstract: A drill bit performs pilot rock-breaking using an outer annular drill bit and breaks a central rock pillar using a central drill bit mounted in the middle of the annular drill bit and located inside a drill bit body to induce unloading of a bottom hole stress. A method mixes rock debris produced by rock breaking of the central drill bit as abrasive with the drilling fluid flowing into the entire drill bit as abrasive jet liquid phase to form an abrasive jet. The method includes obtaining an annular borehole by braking, and breaking the rock pillar at the inner side of the annular borehole to induce unloading of the bottom hole stress, mixing the rock debris produced by breaking the rock pillar at the inner side of the annular borehole as abrasive with the drilling fluid entering the drill bit to form an abrasive jet.

Abstract: The present invention discloses a drilling speed increasing device driven by a downhole motor for generating shock vibration. The device uses the rotational energy of a screw motor as power to drive a lower vibration starter to rotate. Vibration starting steel balls have the function of reducing friction in the interior. During axial reciprocating motion of the upper vibration starter, a spring matched with the upper vibration starter is periodically compressed to generate spring energy. The spring energy reacts on the lower vibration starter and a main shaft connected with a drill bit, so as to periodically provide drilling pressure for the drill bit. Periodic motion of the upper vibration starter and the spring produces periodic axial vibration on the tool.

Abstract: A risk assessment-based design method for a deep complex formation wellbore structure includes: (1) preliminarily determining casing layers and setting depths; (2) calculating to obtain the risk coefficients of each layer of casing; (3) analyzing and coordinating, according to the principle that a shallow casing shares more risks and a deep casing shares less risks, the risks of each layer of casing: determining whether the risk coefficients of each layer of casing are greater than a safety threshold value K; checking the setting depth: if the safety coefficient of an ith-layer casing satisfies RNi>K, selecting a casing layer with the minimum safety coefficient from upper casing layers, and deepening the setting depth h of the casing layer; and (4) repeating the steps (2) to (3) until the casing risk coefficients of each layer of casing are less than the safety threshold value K.

Abstract: A depressurization device for downhole annulus drilling fluid includes a central shaft and a barrel body sheathed outside the central shaft, the central shaft includes a force transmission shaft and a liquid separation piston; the barrel body includes a spline barrel, an elastic element protection barrel, a connector and a depressurization barrel; the elastic element protection barrel and the connector are sheathed outside the force transmission shaft; an elastic element is arranged between the elastic element protection barrel and the force transmission shaft; the depressurization barrel is sheathed outside the liquid separation piston; a first liquid storage chamber and a second liquid storage chamber are formed; a first inlet passage and a first drain passage are formed on the connector; a second inlet passage and a second drain passage are formed on the depressurization barrel; suction valves are arranged on the first inlet passage and the second inlet passage; and, second drain valves are arranged on the

Abstract: A screw drill bypass valve comprising a valve body, the valve body is internally provided with a first-level valve core and a second-level valve core, a first-level spring is arranged between the first-level valve core and the second-level valve core, a second-level spring is arranged between the second-level valve core and a valve seat, and a rigidity of the second-level spring is greater than that of the first-level spring; the first-level valve core is provided with an inner bypass hole, the valve body is provided with an outer bypass hole, and the inner bypass hole is conducted with the outer bypass hole when a flowing pressure within a fluid channel of drilling fluid disappears; the second-level valve core is provided with an inner diversion hole, the valve body is provided with an outer diversion hole.

Abstract: A depressurization device for downhole annulus drilling fluid includes a central shaft and a barrel body sheathed outside the central shaft, the central shaft includes a force transmission shaft and a liquid separation piston; the barrel body includes a spline barrel, an elastic element protection barrel, a connector and a depressurization barrel; the elastic element protection barrel and the connector are sheathed outside the force transmission shaft; an elastic element is arranged between the elastic element protection barrel and the force transmission shaft; the depressurization barrel is sheathed outside the liquid separation piston; a first liquid storage chamber and a second liquid storage chamber are formed; a first inlet passage and a first drain passage are formed on the connector; a second inlet passage and a second drain passage are formed on the depressurization barrel; suction valves are arranged on the first inlet passage and the second inlet passage; and, second drain valves are arranged on the

Abstract: The present invention discloses a drilling speed improvement device capable of producing both hydraulic pulse and impact vibration. The device has a pressure transfer rod that is arranged at an upper end of a lower joint. A spring chamber is formed among a drill body, the pressure transfer rod and the lower joint. A spring is arranged in the spring chamber. A communicating hole is formed in the drill body. A piston is arranged at an upper end of the pressure transfer rod. A pressure bearing head is arranged at an upper end of the piston. A pressure bearing base is arranged on the inner side of an upper joint. Drill bit impact loads and drilling fluid pulse jets are modulated by the longitudinal vibration energy of a drill stem, the rock breaking efficiency of a drill bit is improved by both dynamic and static loads, and harm caused by vibration of the drill stem is reduced.

Abstract: The present invention discloses a drilling speed increasing device driven by a downhole motor for generating shock vibration. The device uses the rotational energy of a screw motor as power to drive a lower vibration starter to rotate. Vibration starting steel balls have the function of reducing friction in the interior. During axial reciprocating motion of the upper vibration starter, a spring matched with the upper vibration starter is periodically compressed to generate spring energy. The spring energy reacts on the lower vibration starter and a main shaft connected with a drill bit, so as to periodically provide drilling pressure for the drill bit. Periodic motion of the upper vibration starter and the spring produces periodic axial vibration on the tool.

Abstract: The present invention discloses a drilling speed improvement device capable of producing both hydraulic pulse and impact vibration. The device has a pressure transfer rod that is arranged at an upper end of a lower joint. A spring chamber is formed among a drill body, the pressure transfer rod and the lower joint. A spring is arranged in the spring chamber. A communicating hole is formed in the drill body. A piston is arranged at an upper end of the pressure transfer rod. A pressure bearing head is arranged at an upper end of the piston. A pressure bearing base is arranged on the inner side of an upper joint. Drill bit impact loads and drilling fluid pulse jets are modulated by the longitudinal vibration energy of a drill stem, the rock breaking efficiency of a drill bit is improved by both dynamic and static loads, and harm caused by vibration of the drill stem is reduced.

Abstract: Disclosed are a screw drill bypass valve with a large displacement diversion function and a method of using same.

Abstract: A weight-on-bit self-adjusting drill bit includes a reaming bit, a WOB adjusting element, a transmission mechanism and a pilot bit and a pulsating impact generating mechanism; the pulsating impact generating mechanism includes a centralizing element, a driving element, a rotating element and a throttling element which are placed and connected successively, the centralizing element, the driving element and the rotating element are connected successively, the throttling element is in clearance fit with the rotating element, both of the centralizing element and the throttling element are respectively provided with a flow-through passage for the drilling fluid to flow through, the driving element drives the rotating element to rotate, the rotating element rotates relative to the flow-through passage on the throttling element.

Abstract: The present application relates to a weight-on-bit self-adjusting drill bit, namely a pulsed jet type weight-on-bit self-adjusting drill bit, comprising a reaming bit, a WOB adjusting element, a transmission mechanism and a pilot bit and a pulsating impact generating mechanism; the pulsating impact generating mechanism comprises a centralizing element, a driving element, a rotating element and a throttling element which are placed and connected successively, the centralizing element, the driving element and the rotating element are connected successively, the throttling element is in clearance fit with the rotating element, both of the centralizing element and the throttling element are respectively provided with a flow-through passage for the drilling fluid to flow through, the driving element drives the rotating element to rotate, the rotating element rotates relative to the flow-through passage on the throttling element.

Abstract: A system for improving a drilling speed by using drill string vibration comprises a downhole drill string vibration-reduction and supercharging device, and an ultra-high pressure bit device used for a downhole supercharger. Also disclosed is a method for improving a drilling speed by using drill string vibration. Related embodiments are also disclosed.

Abstract: A system for improving a drilling speed by using drill string vibration comprises a downhole drill string vibration-reduction and supercharging device, and an ultra-high pressure bit device used for a downhole supercharger. The downhole drill string vibration-reduction and supercharging device comprises a high-pressure runner (16). The ultra-high pressure bit device used for the downhole supercharger comprises an ultra-high pressure drilling fluid transmission runner. The ultra-high pressure drilling fluid transmission runner comprises an ultra-high pressure drilling fluid runner (25), a high-pressure resisting hose (28) and a high-pressure resisting rigid tube (30).