The string for multi-layer negative pressure perforation in one trip in extended-reach directional wells

An extended reach well has large borehole deviation and long displacement, so in the process of perforation completion, the lowering of cable depth correction device and the setting of conventional packer are difficult and the precise negative-pressure perforation cannot be realized, which brings great difficulties to the production of bottom-water oil reservoirs and thin oil reservoirs. In order to realize precise negative-pressure perforation in extended reach wells, the conventional perforation strings were comparatively analyzed firstly. Then, based on the characteristics of extended reach well, the non-rotating setting packer and the logging tool while drilling were introduced, the construction parameters and procedure were optimized, and a set of scheme on multi-layer precise negative perforation in one trip in the extended reach well was optimally designed. And it was tested on site by three well times with daily liquid production of 400 m³/d and water cut less than 10%. The field tests indicate that perforation depth can be determined more accurately by comparing the logging data of drilling with that of perforation, the non-rotating setting packer is advantageous with simple operation and high success rate of one-trip setting. In addition, flowback of crude oil after perforation reveals the effect of negative pressure. It is demonstrated that this perforation string can be better applicable in extended reach wells.