RSS with Near-Bit GR Imaging Assist Accurate Steer Drilling in Shale Gas Project in Sichuan: A Fit-For-Purpose Solutions for Shale Gas Drilling Case Study

Abstract

The Sichuan Basin is the major target for shale gas exploration in China because of its rich gas stored in unexploited black shale with multiple bed series. National Shale Gas Exploitation Areas have been established since 2012, the proved geological shale gas reserves is 9210×108 m3 and 90.25×108m3 annually output has been achieved by the end of 2017. The operating Sichuan Basin shale gas area located in the major compression tectonic experienced multiple geological structure movements in Earth history, showing characteristics of high steep structure with faults greatly developed. It's proven that the key factors in exploiting these targets are well acknowledged by the efforts to land and expose the lateral within the sweet zone. To successfully place lateral in reservoirs from geological perspective must overcome challenges of high uncertainty structure identification to make soft landing and maximize horizontal exposure in the sweet zone. While it comes to shale gas reservoir, to pave the way for fracture operation and achieve good well completion, the drilling requires a relative gentle well path, keeping well path inclination with limitation, which requires to make azimuth turning to achieve this. To ensure the optimum placement of the well in sweet zone, the integration of rotary steerable drilling system (RSS) with borehole images measurements in real-time have been implemented with the employment of well placement technique. The borehole image portrays structural profile while drilling whilst the rotary steerable drilling system provides accurate trajectory control. With the help of borehole image and proactive log correlation, the trajectory can be landed precisely into desired best quality reservoir, although the formation dip and actual target depth become much different with geological prognosis. During the lateral section, the trajectory was also controlled effectively in the high-quality reservoir despite of structural variation and reservoir property change. Through use of Fit-For-Purpose solution it effectively improves drilling efficiency and positively impacts well production. These achievements subsequently help to optimize wells deployment plan and wells with longer lateral horizontal section were planned for greater predictable production rate.

Study on Key Technologies of Geosteering for Shale Gas Horizontal Wells in the Complex Structural Area of Block H in Western Hubei-Eastern Chongqing

“…This is like controlling an airplane from the tail section (noncockpit), without “look-ahead” capability, which may affect the accuracy of geosteering and the actual effect of crossing high-quality reservoirs. In this case, major oil and gas companies have developed geosteering technologies for ahead-of-the-bit investigation, namely, ahead-of-the-bit drilling technology, along-the-bit seismic ahead-of-the-bit technology, and azimuthal electromagnetic wave ahead-of-the-bit technology. − …”

“…In this case, major oil and gas companies have developed geosteering technologies for ahead-of-the-bit investigation, namely, ahead-of-the-bit drilling technology, along-the-bit seismic ahead-of-the-bit technology, and azimuthal electromagnetic wave ahead-of-the-bit technology. 31 − 34 …”

“…Ahead-of-the-bit drilling technology refers to a method and corresponding equipment used in drilling operations to obtain formation data ahead of the drill bit at an earlier stage in the drilling process. 31 This technology enhances the predictive capabilities of geosteering, allowing operators to refine the trajectory during the geosteering phase in horizontal sections. As a result, it ensures a higher probability of intersecting premium reservoirs and produces a more regular wellbore.…”