Practice of drilling optimization system in the development of unconventional oil and gas resources in China

ZHANG Fuxiang1 ZHENG Xinquan2 LI Zhibin1 CHEN Jianlin3 LI Qing3 LU Zongyu3 GONG Xiangmin1 CAO Xinyu1

(1.Strait Energy Co., Ltd.)
(2.PetroChina Exploration & Production Company)
(3.PetroChina Xinjiang Oilfield Company)

【Abstract】Compared with North America, the exploration and development of unconventional oil and gas resources in China started relatively late. Shale gas exploration and development began at the beginning of the “12th Five-Year Plan” period. The exploration and development of tight oil, tight gas, and shale oil started at the beginning of the “13th Five-Year Plan” and developed rapidly during the “13th Five-Year Plan.” In particular, the developments of shale gas in Sichuan and Chongqing, conglomerate oil field in Mahu sag in the Junggar Basin, and shale oil reservoir in Jimsar have entered the stage of large-scale development, becoming the most important field of oil and gas production increase in the end of the “13th Five-Year Plan” and the period of “14th Five-Year Plan” of CNPC. Compared with conventional oil and gas resources, unconventional oil and gas resources have poor reservoir conditions, which requires large-scale “horizontal well + volume fracturing” to achieve effective development. However, due to the limitations of rig equipment and the performance of horizontal well drilling tools, especially the limitations of the concepts and methods, the issues of low drilling efficiency and long well construction period are common in unconventional horizontal wells in China. Generally, the drilling period of horizontal well is 60–90 days, with vertical depth of 2 000–3 000 m and horizontal section length of 1 500–2 000 m. In North America, the drilling period of a horizontal well can be basically controlled within 15–25 days, with vertical depth of 2 000–3 000 m and horizontal section length of 2 000–3 000 m. A drilling rig in China can only drill 2–3 horizontal wells a year, while in North America a drilling rig can complete 15–20 horizontal wells a year. With the large-scale development of unconventional oil and gas resources in China, the contradiction of drilling rig shortage is increasing. Drilling efficiency has become a bottleneck problem that seriously restricts the rapid and large-scale production of unconventional oil and gas resources in China. There are two advantages for the great improvement of drilling efficiency of horizontal wells in North America: management and technology. For technology, there are mainly five aspects: The first is the continuous upgrading of drilling rig supporting capacity; the second is the improvement of the reliability and stability of downhole tools; the third is the large-platform factory operation; the fourth is the remote real-time support and decision-making system, and the fifth is the application of the concepts and methods of systematic drilling optimization. In 2018, Strait Energy Co., Ltd. cooperated with K&M drilling engineering consulting company of the United States to introduce internationally-advanced concepts and methods of systematic drilling optimization. The pilot test of drilling speed increase of horizontal wells was first carried out in Changning Shale Gas Co., Ltd. in Sichuan–Chongqing area, and in the conglomerate oil field in Mahu sag in Xinjiang, which greatly shortened the well construction period and verified the feasibility of systematic drilling optimization methods in the development of unconventional oil and gas resources in China. In order for further promotion, in 2019, the test of speed increase in the whole block was carried out in the conglomerate oil field in Mahu sag, which also achieved remarkable results. It further proves that the concepts and methods of systematically optimized drilling speed increase are scientific, universal and replicable, which is an important practice from experience drilling to scientific drilling, and shows a very promising popularization and application prospect.

【Keywords】 unconventional oil and gas resources; shale revolution; systematic drilling optimization; well construction cost;

【DOI】

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This Article

ISSN:1672-7703

CN: 11-5215/TE

Vol 25, No. 02, Pages 96-109

March 2020

Downloads:3

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Article Outline

Abstract

  • 0 Introduction
  • 1 Overview of unconventional oil and gas development in the United States
  • 2 Concepts and methods of systematic drilling optimization
  • 3 Pilot tests on concepts and methods of systematic drilling optimization in China
  • 4 Promotion of concepts and methods of speed increase in systematic drilling optimization in the Mahu conglomerate oil field
  • 5 Conclusions
  • References