Forward and reverse circulation assembly for core drilling tools and coring operation method utilizing the same

A forward and reverse circulation assembly for core drilling tools, comprising:

• an outer tube body;
• an inner receiving body, configured to accommodate rock cores, provided inside the outer tube body, and a drilling fluid channel is provided between the inner receiving body and the outer tube body;
• at least one longitudinal fluid acceleration groove is provided on an outer peripheral wall of the inner receiving body, and the at least one longitudinal fluid acceleration groove is configured to form a negative pressure zone by increasing a local flow velocity when a drilling fluid flows through;
• a reverse circulation channel, which communicates a lower rock core inlet of the inner receiving body with the negative pressure zone, and is configured to use a suction effect generated by the negative pressure zone to extract some drilling fluid and rock cores upwards from the rock core inlet, thereby forming a local reverse circulation;
• wherein a mainstream drilling fluid that has not formed the local reverse circulation continues to flow along the drilling fluid channel to form a forward circulation;
• wherein the inner receiving body comprises a recycling tube, a docking part is provided at a lower end of the recycling tube;
• the docking part is sleeved with a core taking tube, the at least one longitudinal fluid acceleration groove is provided on an outer peripheral wall of the docking part;
• wherein the forward and reverse circulation assembly further comprises an annular sealing member that is arranged around the docking part and adjacent to the at least one longitudinal fluid acceleration groove;
• wherein the annular sealing member divides the drilling fluid channel into a first channel located above the annular sealing member and a second channel located below the annular sealing member;
• a water inlet groove is provided at an upper edge of the docking part, and the at least one longitudinal fluid acceleration groove is connected below the water inlet groove;
• the water inlet groove and the at least one longitudinal fluid acceleration groove jointly communicate the first channel and the second channel.