Abstract: A method for creating branch fractures in an oil well, including: injecting a first pad fluid containing a first absorbent resin to a first position of the main fracture; injecting a second pad fluid containing a second absorbent resin to a second position of the main fracture; after the second absorbent resin absorbs water and expands to form a first plugging layer, injecting a third pad fluid free of absorbent resin to the main fracture to build up a pressure at the first plugging layer; exerting the pressure to sides of the main fracture to form a first branch fracture; breaking the first plugging layer to generate a fragment; bridging the fragment to the first absorbent resin to form a second plugging layer; and injecting a third pad fluid to build up a pressure to form a second branch fracture at the first position.

Abstract: Disclosed is a device and method for measuring the magnitude of a seepage force and its influence on effective stress of a formation. The measuring device includes a lower bearing platform having a pressure testing device fixed on an upper part thereof, and a water storage chamber mounted with a seepage water discharge pipe. A confining pressure loading chamber is mounted on the upper part of the lower bearing platform, and the lower bearing platform is used for placing a sample which has 11 measuring points distributed at equal intervals on an outer wall thereof. An upper and a lower permeable pressure-bearing steel sheet are placed on an upper and a lower end surface of the sample, respectively. The invention can improve the validity and accuracy of measurement and make the calculation result of the test more accurate.

Abstract: A method for creating a branch fracture with temporary plugging and pressure buildup using super absorbent resin, comprising: setting a fracturing packer to fracture a target layer by pad fluid to form a main fracture; injecting into the main fracture pad fluid mixed with salt-intolerant super absorbent resin and performing replacement till depth of the main fracture, and then injecting pad fluid mixed with strong salt-tolerant super absorbent resin; after the strong salt-tolerant super absorbent resin absorbs water and expands to form a temporary plugging layer, re-injecting the pad fluid to create a branch fracture with pressure buildup; and lifting injection pressure to break up the temporary plugging layer formed by the strong salt-tolerant super absorbent resin to form residue, transporting the residue to the depth of the main fracture to bridge the temporary plugging layer formed, and re-building up pressure to create a branch fracture.

Abstract: Disclosed is a device and method for measuring the magnitude of a seepage force and its influence on effective stress of a formation. The measuring device includes a lower bearing platform having a pressure testing device fixed on an upper part thereof, and a water storage chamber mounted with a seepage water discharge pipe. A confining pressure loading chamber is mounted on the upper part of the lower bearing platform, and the lower bearing platform is used for placing a sample which has 11 measuring points distributed at equal intervals on an outer wall thereof. An upper and a lower permeable pressure-bearing steel sheet are placed on an upper and a lower end surface of the sample, respectively. The invention can improve the validity and accuracy of measurement and make the calculation result of the test more accurate.