American Oil and Gas Reporter - April 2015 - 134

SpecialReport: Performance Drilling

Program Optimizes Bakken Drilling
By Matthew Isbell,
Ramiro Ndong,
Ryan Miller,
Isaac Fonseca,
Doug Tinsley,

HOUSTON-Oil and gas operators are
leading the way in developing and applying drilling optimization systems, allowing them to collaborate more effectively with service companies as well as
improve their drilling economics. They
have combined their efforts with those
of large equipment manufacturers that
have extensive knowledge of solutions
provided by advanced technology. Together, these entities can address the
drilling challenges of each application
and establish new performance indicators
that push the boundaries.
Hess Corporation's optimization program is a drilling-specific approach to
the continuous improvement cycle. It
adopts key elements from programs for
managing rate of penetration, lean manufacturing concepts, and the operator's
drilling needs and practices. The program
uses "plan, do, check, adjust (PDCA)"
as the four basic phases, with additional
drilling-specific activities covered in each
step.
A drilling-specific, continuous improvement process was implemented on
a five-well project in Dunn County, N.D.,
to understand the impact of drilling dynamics and system interaction on drilling
objectives and value drivers. Multiple
downhole dynamics recorders validated
the improvement process by monitoring
bottom-hole assembly characteristics and
operating practice effectiveness. Key performance indicators (KPIs) were established, based on vibration levels from
the downhole dynamics recorders, drilling
hours, and interval hours.
The test program demonstrated the
importance of program tools such as a
"driller's road map," which was refined
from a benchmark well drilled with regular
drill-off tests to encourage a consistent
approach to operating practices. The BHA
characteristics, operating practices, and
drill bits were identified as the ROP limiters after analyzing the KPIs. This resulted
in inconsistent runs and vibration damage
to the drill bit cutting structures.
Tests with three basic BHA configurations identified drilling system vibration

characteristics, which were optimized to
yield the best results. ROP limiters identified by data analysis were addressed,
and significant adjustments were made
to the BHA and operating parameters as
the PDCA cycles progressed. A "lessons
learned" catalog documented key changes
and performance impacts.
The optimization cycle yielded an average 33-hour reduction in drilling time
per well for the first pad compared with
the rig's benchmark well. This resulted
in saving $88,335 a well, for a total
savings of $353,340 for the first pad.
The optimization project continues to
fine tune the driller's road map. Improved
performance and cost savings were sustained throughout the optimization process,
and larger gains are expected to be realized
in future drilling.
Creating Value With PDCA
The basic PDCA improvement workflow creates and protects value by identifying and addressing waste. The process
is useful to identify and address value
limiters to provide continuous improvement.
The continuous improvement cycle
can start with any of the PDCA phases,
depending on the need of the drilling
program:
* Plan (optimize the system to improve its function and develop an implementation plan);
* Do (implement the plan, monitor
its execution, and implement corrective
action when needed);
* Check (analyze and recap results,
capture lessons, and drive improved practice); and
* Adjust (identify and remove a limiter, and find system limits and limiting
factors).
Value limiters are processes, materials,
tools or practices that restrict the value
of a well. There is always a controlling
limiter determining value. Limiters usually
are part of the planned operations.
ROP limiters are one form of value
limiter. Other drilling value limiters are
wellbore placement in the reservoir that
limits ultimate production, flat time or
nonproductive time that introduces cost
and delays, and the cost of tools and
equipment for a specific drilling operation.
Applying optimization strategies can mitigate limiters.

134 THE AMERICAN OIL & GAS REPORTER

This process is beneficial in developing
a better understanding of system interaction
with drilling objectives and value drivers.
In this case, it led to an understanding of
drilling system inefficiency where the
wasted energy damaged system components and limited ROP.

Trouble Zone Drilling Challenges
Rock formations south of North Dakota's Lake Sakakawea trend are deeper
than the formations to the north, presenting
a variety of drilling challenges. Drilling
multiple stringers of rock midway through
the vertical interval always resulted in
damage to the drill bit and a trip to
replace it.
Two trouble zones were identified
from earlier offset wells. One or more
trips caused by low ROP were made
while drilling zone 1. Challenges in zone
2 were related to low ROP and low
drilling efficiency. A drilling days-versus-depth curve of offset wells illustrates
performance trends in the two zones (Figure 1). Drilling performance was known,
but the root causes generating this performance were not well understood.
Improvement project work started with
analyzing well records. The first well
was drilled with measurement tools and
numerous drill-off tests to generate a
benchmark. The benchmark well is referenced as well A. Three dynamics data
recorder (DDDR) sensors were placed in
the BHA for consistency of the dynamics
data analysis with the intention of running
the first two sensors in compression and
the third in tension.
The DDDRs are high-frequency, memory-mode, vibration logging devices that
can be placed in tools, tubulars or bits,
and acquire torsional, lateral and axial
vibration, downhole temperature, and
downhole revolutions per minute.
The five-well case study used the
DDDR tools to analyze drilling dynamics
data and follow the PDCA structure. A
similar interval was drilled on each well
with a different BHA design, based on
the lessons learned and operational feasibility. Data analysis often was completed
prior to the next well, so the PDCA cycle
proceeded at the pace of data analysis.
Benchmark Well Vibrations
Well A (the benchmark) was drilled
with BHA one, which included nine 61⁄2-

American Oil and Gas Reporter - April 2015

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