American Oil and Gas Reporter - April 2019 - 60

SpecialReport: Drilling Technology

Integrated Approach Characterizes Plays
By Troy Tittlemier,
John Speight,
Charles Hager
and Isaac Easow
MIDLAND-There are thousands of
feet of stacked unconventional targets
from the top of the Leonardian to the
base of the Wolfcampian in the southern
Delaware Basin. While the liquids-rich
Bone Spring and Wolfcamp formations
are the primary focus of horizontal activity,
operators in the basin also know there
are multiple prospective productive Paleozoic formations both above the Bone
Spring and Wolfcamp in the overlying
Delaware Mountain Group as well as below in underlying intervals from the Pennsylvanian down to the Ordovician-including the Mississippian Woodford.
In deeper Paleozoic formations below
the Permian-aged Bone Spring and Wolfcamp, the thermal maturity of the source
rocks increases and reservoir fluid is expected to be predominantly gas. There
are indications of potential liquid-rich
production in specific geological, structural
and thermal maturity settings, but only a
limited number of laterals have been
drilled and completed to date in deeper
Paleozoic formations across the basin.
To evaluate a project in a comparatively

new area in the southern Delaware Basin
with scarce offset well information, Trey
Resources implemented a comprehensive
reservoir characterization approach based
on advanced surface logging measurements collected while drilling one vertical
pilot and two horizontal wells targeting
the Wolfcamp and Woodford. Mud gas
geochemistry, fracture detection from
mud flow, chemostratigraphy and source
rock evaluation were used to characterize
both rock and fluid properties, and the
resulting data were integrated with openhole wireline log data to identify landing
targets and optimize completion design.
The integrated approach represents a
nonintrusive and cost-effective alternative
for reliable formation evaluation. The insights gained can help operators map regional hydrocarbon distribution, locate
fracture-prone reservoirs, predict fracturerelated porosity and permeability, identify
faults, estimate gas-to-oil ratios, identify
higher water production intervals, and plan
future drilling and completions strategies
for both primary and secondary targets.
In this project, the best points for
landing depths in both the Wolfcamp and
Woodford were selected by evaluating
reservoir quality, production potential,
reservoir compartmentalization, source
rock character, microfractures, estimated

FIGURE 1
Composite Log Showing Reservoir Fluid Characterization
Using Light Hydrocarbon Gas Data and Ratios
Gamma

Lith

XRD

TGAS vs ROP

TGAS Normalized

Middle Paleozoic

7,000 ft

Upper Paleozoic

Depth

Lower Paleozoic

60 THE AMERICAN OIL & GAS REPORTER

C1-C3

C4-C5

C6+

Haworth

Neutron Por Dens

reservoir fluid type, and predicted GOR.
The surface logging techniques also were
used to aid in geosteering the laterals
and provide inputs for reservoir quality
typing and well completion.
The objectives of the formation evaluation program included measuring hydrocarbons, gas isotope ratios and helium
in the formation from the drilling fluid,
organic and inorganic geochemical evaluation from drill cuttings, and formation
fracture detection from advanced flow
measurement of drilling fluid returns.
These acquired data were utilized to evaluate the fluid properties and reservoir
quality of each potential hydrocarbonbearing layer in the vertical well, which
then aided in selecting landing points
and designing completions for the two
horizontals.
Project Workflow
The workflow encompassed:
· Identifying formations with significant hydrocarbon saturation and evaluating
formation fluid composition and gas isotopic ratios in the vertical pilot;
· Utilizing fluid composition and isotopic data to predict reservoir fluid type;
· Collecting organic and inorganic
measurements from drill cuttings to characterize the chemical composition, bulk
mineralogy and source rock production
potential and maturity;
· Measuring the quantity/quality of
oil present in select samples to characterize
heavier hydrocarbons and integrate with
light hydrocarbons measured from mud
gas analysis;
· Identifying natural fractures using
surface flow measurements, X-ray fluorescence (XRF) and helium detection;
· Selecting landing targets for drilling
the laterals;
· Defining the target lithology with
chemostratigraphy in the vertical well
for geosteering the laterals; and
· Detecting drill bit metamorphism
and evaluating drill bit performance to
identify early bit wear and provide
geosteering inputs to steer away from
abrasive rock that prematurely wears bits.
With a lack of nearby offset wells
and reservoir characteristic information
available, the primary objective of the
formation evaluation program was to assess the hydrocarbon potential of various
formations in the upper and lower Pale-
American Oil and Gas Reporter - April 2019

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