Accurate Geosteering Technology for Deep Shale Gas Based on XRF Element Mud Logging

TANG Cheng1 WANG Zhizhan2 CHEN Ming3 WANG Chongjing1 LIANG Bo1 SHI Qiang1

(1.Geological Logging Branch, Sinopec Xinan Oilfield Service Corporation, Mianyang, Sichuan Province, China 621000)
(2.Sinopec Research Institute of Petroleum Engineering, Beijing, China 100101)
(3.Oil and Gas Exploration Management Department, Sinopec Southwest Oil & Gas Company, Chengdu, Sichuan, China 610041)

【Abstract】During the drilling of the deep shale gas horizontal wells in the Weirong Shale Gas Field in southern Sichuan, it is very difficult to accurately identify the marker bed, determine the bit position and judge the penetrating state of the bit. To solve this problem, we used X-ray fluorescence (XRF) element mud logging data to establish a three-terminal chart, an element intersection chart and a three-dimensional element display chart, as well as a quantitative calculation model of evaluation parameters such as rock density and gas content. The geosteering technology has been formed by such a principle: A three-terminal chart was used to identify the key marker beds before window-entering; the element intersection chart was used to guide the accurate window-entering of horizontal wells; the three-dimensional element display chart was used to determine the penetration of the bit in a horizontal section; the shale density, gas content, etc., were used to guide the optimization of horizontal wellbore trajectories. This technology has been applied in 18 horizontal shale gas wells in the Weirong Shale Gas Field, with the average drilling rate of the target up to 98.06%. Research results showed that the technology could improve the rate of encountering high-quality reservoirs by accurately identifying the marker bed, determining the bit position and judging the penetrating state of the bit.

【Keywords】 deep shale gas; XRF element mud logging; interpretation chart; mathematical model; geosteering; Weirong Shale Gas Field;

【DOI】

【Funds】 Sinopec Scientific and Technological Key Project (P17014-9)

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This Article

ISSN:1001-0890

CN:11-1763/TE

Vol 47, No. 06, Pages 103-110

November 2019

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Article Outline

Abstract

  • 1 Stratigraphic features
  • 2 Technical difficulties of geosteering
  • 3 Accurate geosteering technology
  • 4 Field application
  • 5 Conclusions and recommendations
  • References