Abstract

It's a difficult problem all the time to shape and enlarge the hole diameter of casing damage well with a small diameter in the workover job of casing damage well. In the light of the condition of increasingly serious casing damage in Xingbei Oilfield, six kinds of composite drilling tools were designed and applied since 1999. The in-site applications show that the technique can obtain a better result in shaping and enlarging the hole diameter of small-diameter casing damage well. The structure of 6 combined drilling tools and the field application. are described in the paper.

Introduction

Xingbei oilfield is the most serious casing damage region in Changyuan of Daqing.102 wells has been enlarged the hole diameter during 1996–1998, of which 38 wells above 90mm with a success rate of 86.8%;10 wells 81–90mm with a success rate of 30%; 19 wells 71–80mm with a success rate of 16%;35 wells below 70mm with a success rate of 8.6%. Therefore, in order to improve restoring rate, the study on expanding the hole diameter of casing damage well must be strengthened.

The Structure of Composite Drilling Tools for Treating Casing Damage Wells With Small Diameter

  1. Hammer pre-treatment shaping composite drilling tool. Hammer pre-treatment shaping composite drilling tool is mainly made up of eccentric tube expander and jarring device. Eccentric tube expander helps insert small diameter broken joint. The main effect of jarring device is to transfer torque during looking for broken channel, eusure eccentric tube expander to insert broken channel. transmit the impact pressure of drilling pipe on the eccentric tube expander during jarring and tube expanding, avoid eccentric tube expander separating from broken channel because of lifting drilling tool during expanding tube.

  2. Constant bit weight pre-treatment milling combined drilling tool.Constant bit weight pre-treatment milling combined drilling tool is mainly comprised of needle probe milling cone, floating coupling and bit weight controller. Needle probe milling cone includes mainly milling cone and guide rod, its feature is that the guide rod can always guide milling cone in the broken channel, avoid deflection milling from casing. Floating coupling is a kind of free joint that not only transfers torque but also can deflect within a range of 10 °, its feature is that it can solve the problem needle probe milling cone isn't concentric with drilling pipe and break needle probe milling cone. Bit weight controller is equal to a expansion joint which can transfer big torque with an effective trip of 1.8m.The feature is to ensure a constant bit weight, avoid fluctuation caused by weight indicator and manual operation factor, improve milling efficiency, extend service time of milling tool, reduce greatly the frequency of driller operating brake handle, alleviate labor strength.

  3. Constant bit weight, forced centralizing, casing milling composite tool. Constant bit weight, forced centralizing, casing milling composite tool consists of dual-type milling barrel, drill collar, rolling centralizer and bit weight controller.

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