Page 398 - Fundamentals of Gas Shale Reservoirs

378 GAS SHALE CHALLENGES OVER THE ASSET LIFE CYCLE

several drilling days. A rotary steerable system 10. The type of wellbore completion used directly affects
(RSS) is typically more efficient due to its automatic efficiency during the fracturing process.
steering capability and results in a much better hole 11. Each completion technique has its own benefits and
condition than provided by motors. considerations, dependent on application and the
• Drilling optimization increases drilling efficiency current phase of the asset life cycle.
and reduces days on wells (cost). 12. Use plug‐and‐perf during appraisal phase to provide
• Effective well placement using reservoir navigation flexibility of stage placement, resulting in more time
maximizes reservoir exposure and locates the well to gather data.
in the sweet spots. 13. Ball‐activated systems provide efficiency during
• Environmentally friendly WBM, which is more development phase (when more information is
economic and provides the preferred characteristics known about the reservoir). This type of completion
of an OBM, is recommended for drilling the curve system is preferred by operators in liquids plays.
and lateral. 14. Coiled tubing–activated systems offer accuracy and
4. A successful fracture stimulation is the one that contingency options and can result in optimized fracs
increases productivity index as well as ultimate during the development phase. These systems can be
recovery of a producing well in an economic, safe, and run in both open‐hole and cased hole completions.
environmentally friendly manner. This involves not
only executing a proper treatment design but also the Production Phase
placement of the frac stages at the proper place along
the horizontal lateral. 1. Monitor and control the flowback rate of the com-
5. Overcoming all of the hydraulic fracturing challenges pleted well in order to optimize total recovery and pre-
of (a) achieving designed fracture geometry, (b) trans- vent well damage.
porting proppant to the right location, (c) achieving 2. Periodically, run PLTs to assess production problems
final conductivity, (d) encountering expected reservoir and consider possible remedial well work.
properties, and (e) avoiding geohazards will certainly 3. Manage the complete water cycle—sourcing for dril-
lead to the “optimum fracturing treatment.” ling and fracture water; lifting, treating, handling,
6. The design of the frac begins with collecting a number storage, and disposal of well flowback water.
of key parameters about the reservoir and the well. 4. Install artificial lift if required.
These data are used as input in a fracture simulator 5. Implement production chemical monitoring and
(recommended) to design the treatment with proper treatment equipment and programs.
frac fluid, proppant, additives, and pumping schedule. 6. Protect the environment throughout all operations,
There is no optimum, one‐size‐fits‐all stimulation especially when hydrocarbons and water are brought
design for shale wells; each frac design is dependent to the surface.
on the parameters of a specific well in a specific
formation, at a specific location, and for the type of
produced fluid expected. Rejuvenation Phase
7. Use microseismic while implementing the frac in 1. Evaluate wells as re‐frac candidates. Select the appro-
order to obtain near real‐time information to control priate wells and conduct the re‐frac operation. Refracs
frac direction and limit loss. Microseismic also pro- have been determined to be the one significant method
vides an approximate stimulated reservoir volume for to arrest the rapid decline in shale wells and increase
input into a reservoir simulator to determine predicted production rate.
recovery. 2. Redevelopment (probably infill drilling) can be con-
8. In order to place the frac stages and perforation clus- sidered when the primary development in the sweet
ters in the optimum location along the lateral, the lat- spots of the field have been or are nearing depletion.
eral should be characterized in order to obtain critical
information about natural and conductive fractures
and reservoir characteristics. ACkNOWLEDGMENTS
9. Characterizing the lateral to obtain these two different
data aspects can be accomplished by running an LWD This author would like to thank the management of Baker
high‐definition image log (for fracture information) Hughes for allowing him to write and contribute this chapter
and running advanced mud logging with cuttings anal- to the book. I would also like to thank and show my appreci-
ysis (mineralogy and reservoir data). ation to the members of the Baker Hughes Unconventional