American Oil and Gas Reporter - June 2018 - 66

SpecialReport: Permian Basin Activity

Oxy Optimizes Delaware Basin Drilling

HOUSTON-The northern part of the
Delaware Basin in southeastern New Mexico
is a difficult geological area. The economic
success of unconventional development
projects is heavily dependent on minimizing
well cost, requiring complex optimizations
to horizontal drilling operations.
To achieve its objectives in the New
Mexico Delaware Basin, Occidental Oil
& Gas Corp. (Oxy) systematically has
made optimizations to well designs and
drilling practices as part of a continual
improvement process. This article presents
several of the optimizations developed
during the course of drilling 179 horizontal
wells from 2012 through late 2017 in
southeastern Eddy County, N.M. A variety
of wells were drilled in numerous areas,
but most were in the Cedar Canyon and
the Sand Dunes areas, where multiple
stacked productive intervals are a significant
factor in field development planning.
The work has addressed high-pressure
flows, lost circulation, salt and anhydrite,
and multiple drilling effects. Successful
practices defined from the study include
casing design and setting depths, bits,
rotary steerable systems (RSS), rig specifications, and pad layout. Mud systems
analyzed included brine, mixed-metal hydroxide, invert and direct emulsions.
Techniques to predict, prevent and mitigate
downhole vibration effects also were established, including bit and bottom-holeassembly design and operating practices.
By continually improving best practices
and well designs, overall drilling speed
was increased by 149 percent as measured
by feet per day during the five-year study
period. Average lateral lengths increased
from 3,000 feet in 2016 to 7,000 feet in
2017, with 10,000-foot laterals now common. Rig capabilities, pad layout, casing
designs, drilling fluids, drilling dynamics
and other designs and practices all have
been improved significantly over the past
three years as Oxy has implemented the
performance optimizations.
A methodical approach to vibrations
has proven critical to consistent horizontal
66 THE AMERICAN OIL & GAS REPORTER

drilling performance. Direct emulsion mud
also has shown promising results as a lowdensity fluid with a salt-saturated water
phase. Casing designs were optimized to
eliminate strings in some cases, and to
reduce hole sizes in other cases. Casing
programs evolved to include two-, threeand four-string designs, with some wells
requiring two intermediate strings in addition
to surface and production strings. Rig modifications also were required to support
long laterals and larger drill pipe sizes.
Total measured depths for the 179
wells range from less than 10,000 to
more than 20,000 feet, with measured
depths progressively becoming greater
over time. Vertical depths for wells in
the study are between 5,000 and 12,000
feet with lateral lengths classified into
three groups: laterals between 3,000 and
6,000 feet are considered "5K" laterals,
those between 6,000 and 8,000 feet are
"7.5K," and any lateral longer than 8,000
feet is considered "10K."
Drilling times varied throughout the
study period. The highest variation and
longest total days per well occurred in
2012 and 2013, the start of active horizontal drilling in the area. Drilling times
have improved dramatically as a result
of numerous performance optimizations
implemented since 2015. The most relevant
optimizations include:
* Well designs, specifically hole and
FIGURE 1
Stacked Producing Benches
In Sand Dunes Area

Brushy Canyon

Avalon

H
H

6,000 ft

By John Willis,
Diego Tellez,
Randy Neel,
Greg Caraway,
Derek Adam
and John Rodriguez

H
H
H
H

Proven Economic

Wolfcamp D

1st Bone Spring
2nd Bone Spring

3rd Bone Spring
Wolfcamp X-Y
Wolfcamp A

Wolfcamp D

casing sizes, and casing setting depths;
* Drilling operational improvements
in each hole section;
* Multiwell pad design considerations;
* Drilling fluids and cementing, particularly managing salt zones with water
flow and low-integrity fluid loss zones,
and achieving cement-to-surface in areas
with low formation integrity;
* Advanced rig designs integrating
key operational specifications;
* Vibration training, including implementing a certification process to attain
consistent application of advanced vibration control methods; and
* Downhole tool quality assurance
and quality control, including an inspection
program to complement vibration reduction for reducing downhole tool failures.
Stacked Intervals
As part of its 2.5 million net acre
position in the Permian Basin, Oxy holds
290,000 net acres on the New Mexico side
of the Delaware Basin along with 150,000
net acres on the Texas side. The Greater
Sand Dunes Field is typical of Oxy's New
Mexico Delaware Basin holdings. It exhibits
a common scenario of four proven formations-Brushy Canyon, Second Bone Spring,
Third Bone Spring and Wolfcamp X-Y-
and four more potential formations still
being delineated-Avalon, First Bone Spring,
Wolfcamp A and Wolfcamp D-over a
6,000-foot vertical column (Figure 1).
Oxy has identified more than 2,000
drilling locations in Greater Sand Dunes,
with development planning based on standard
one square-mile sections using multiwell
pads to accommodate the number of wells
per section required to develop each bench.
Wells are drilled across one section (5K
laterals), one-and-a-half sections (7.5K laterals) and two sections (10K laterals).
Another significant factor in operations
in New Mexico is federal governmentowned land, administered by the Bureau
of Land Management. In addition to
BLM's robust regulations on federal lands,
there is a large area of potash reserves in
the area, with several operating mines.
Drilling within potash areas must comply
with additional special rules to protect
the integrity of existing mines and maintain
the ability to mine new areas in the future.
Southeast New Mexico's sparse highway

American Oil and Gas Reporter - June 2018

Table of Contents for the Digital Edition of American Oil and Gas Reporter - June 2018