Well drilling tool and method for determining parameter thereof

A drilling tool, comprising:

• an upstream drilling string;
• a downstream drilling bit;
• and
• a percussive device connected between the upstream drilling string and the downstream drilling bit,
• wherein in a first state, an elastic compression force is generated within the upstream drilling string by the percussive device, and
• in a second state, the upstream drilling string releases the elastic compression to apply impacts on the downstream drilling bit through the percussive device,
• wherein the percussive device comprises:
• a rotary driving part configured to be rotatable about its axis;
• a rotary working part, which has an upper end in engagement with a lower end of the rotary driving part and a lower end connected with the downstream drilling bit, wherein the rotary working part is configured to be driven by the rotary driving part to rotate about its axis, and axially movable relative to the rotary driving part;
• and
• a percussion generating part arranged around the rotary working part, the percussion generating part having an upper end abutting against the upstream drilling string and a lower end abutting against the rotary working part,
• wherein in the first state, the percussion generating part moves upstream so that the upstream drilling string is generated with the elastic compression, and
• in the second state, the upstream drilling string releases the elastic compression, so that the percussion generating part moves downstream to apply impact on the rotary working part,
• wherein the rotary driving part comprises a cylindrical driving rod, which has an upper end coupled with a power source, and
• the rotary working part comprises a cylindrical rotary rod, which has an upper end in engagement with a lower end of the driving rod through a driving key, and a lower end connected with the downstream drilling bit,
• wherein the upper end of the rotary rod is inserted into the lower end of the driving rod and provided at an outer side thereof with the driving key extending along an axial direction of the rotary rod, and the lower end of the driving rod is provided at an inner side thereof with a driving slot extending along an axial direction of the driving rod, wherein the driving key is fitted in the driving slot, so that the rotary rod is fixed relative to the driving rod along a circumferential direction, and movable relative thereto along the axial direction,
• wherein the percussion generating part comprises a percussive sleeve, which is arranged around the rotary rod, and has a first sleeve segment with a relatively small inner diameter and a second sleeve segment with a relatively large inner diameter, the second sleeve segment being arranged below and connected with the first sleeve segment, wherein an upper driven tooth is formed at an inner side of the percussive sleeve in an area connecting the first sleeve segment with the second sleeve segment,
• the rotary rod includes a first rotating segment with a relatively small outer diameter and a second rotating segment with a relatively large outer diameter, the second rotating segment being arranged below and connected with the first rotating segment, wherein a lower driving tooth is formed on an outer side of the rotary rod in an area connecting the first rotating segment with the second rotating segment, and
• the lower driving tooth and the upper driven tooth are configured to be in cooperation with each other, so that when the rotary rod rotates relative to the percussive sleeve, the percussive sleeve reciprocates axially relative to the rotary rod under the cooperation between the lower driving tooth and the upper driven tooth.