Drilling and Completion System of Shale Gas Based on Drilling Robot With Multi-Branch Micro-Wellbores

Abstract

In this paper, a new technology for shale gas & oil well drilling, completion and stimulation is formed. A drilling micro-robot was proposed and equipped between the micro-bit and coiled tubing drilling strings. Drilling robot helps the micro-bit to drill high-density multi-branch micro-wellbores. After drilling, a directional blasting in each branch micro wellbore, is performed to frack the shale formation. The drilling robot and blasting completion tool were designed and manufactured, and the initial performance parameters was obtained.

Shale gas hydraulic fracturing needs substantial water consumption and seriously pollutes the environment. Drilling costs of a micro-well (diameter less than 89mm) can be reduced by 30-40%. The use of blasting fracturing technology can not only save water resources, but also can minimize the environmental and reservoir pollution. It is expected that the cost of blasting fracturing is only about 30% of the cost of conventional hydraulic fracturing, and also thousands of water are saved. Therefore, multi-branch micro-wellbore combining with blasting fracturing are an important research direction of shale gas exploitation.

Some preliminary conclusions were obtained. (1) The structure of drilling robot was designed and manufactured (maximum diameter 80mm, length 5m, traction force more than 60000N, orientation accuracy less than 5°). (2) A closed-loop control system composed of feed control system, orientation control system and ground control system was proposed. The control system can achieve semi-automatic or fully automatic drilling operations. (3) A blasting fracturing tools was designed, including the branched wellbore identification system, the branch hole reentry structure and the explosive loading mechanism.

This paper makes the following contributions: (1) A new shale gas & oil exploitation technology by multi-branch micro-wellbores has the advantages of economy, environmental protection and safety. (2) A drilling robot is developed for automatic traction and drilling orientation in micro-wells. (3) A multi-branch micro-well blasting method is also proposed.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018