American Oil and Gas Reporter - November 2015 - 82

SpecialReport: MWD/LWD Technology
can be inferred with the help of imaging software for wellbore
placement (Figure 2). The third and fourth tracks from the top
in Figure 1 represent the density and gamma data, respectively,
in which the dashed lines correspond to the predicted data, and
the solid lines illustrate the actual data.
Figure 1 illustrates that the predicted and actual data from the
third and fourth tracks show good correlation. The pink line represented in the fifth track outlines the well trajectory inside the
Lower Barnett Shale. The two tracks shown on the right display
the gamma and density data obtained from the offset vertical well.
The horizontal well was drilled above the Viola Limestone, which
has been known to contain mobile water. The Viola Limestone
is represented in light blue.
Petrophysical Data Evaluation

Because the case-study well lies outside the normal productive Barnett trend, full wireline and LWD quad-combo data were
acquired. To better understand well performance, it was necessary to evaluate the petrophysical data from the vertical offset and
horizontal wells. Figure 3 illustrates the evaluation of wireline
data acquired from the vertical offset well.
Track 1 in Figure 3 is depth, track 2 represents the gamma and
apparent water resistivity from the offset well, and track 3 illustrates resistivity. Track 4 details the density, neutron, and sonic
data acquired using wireline tools. Track 5 shows the petrophysical evaluation of mineralogy and fluid volumes, and track 6 repFIGURE 3
Fluid Volume, Mineral Evaluation and
Rock Mechanical Properties of Offset Vertical Well

resents the brittleness calculated from Poisson's ratio and
Young's modulus, taken from the sonic and density data. Track
7 also provides information on the fluid volumes taken from track
5, including Young's modulus and Poisson's ratio. Finally, the
closure pressure gradient profile is represented in track 8.
Closure stress as well as kerogen, mineralogy, and porosity
distributions were calibrated to the vertical pilot-hole logs and
full core properties.
The horizontal well was drilled between 7,700 and 7,750 feet
true vertical depth from the offset well. In that area and close by,
a higher stress zone was observed at approximately 7,710 and
7,800 feet TVD. Models demonstrate that these two zones restrict
the height of the fracture.
Hydraulic fracture simulator modeling performed at two depths
indicated that the zones located at 7,710 and 7,800 feet TVD were
fracture barriers. The results from the model indicated that the
water-bearing Viola Limestone would never be fractured from
the horizontal well.
After the petrophysical evaluation of the vertical offset well,
the same evaluation was performed on the horizontal well with
the acquired LWD data (Figure 4).
Track 1 in Figure 4 is depth, track 2 represents the gamma and
well path, and track 3 shows the true resistivity. Track 4 outlines
the density, neutron, and sonic data acquired with the LWD tools.
Track 5 illustrates the petrophysical evaluation of the mineralogy
FIGURE 4
Fluid Volume, Mineral Evaluation and
Rock Mechanical Properties of Horizontal Well

7,500

8,400

7,550

7,600

7,650

Top of
Lower
Barnett

10,000
10,400

7,750

10,800

7,800

7,900

82 THE AMERICAN OIL & GAS REPORTER

9,200
9,600

7,700

7,850

8,800

11,200

Viola
Limestone

11,600
12,000

American Oil and Gas Reporter - November 2015

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