American Oil and Gas Reporter - April 2020 - 57

pages 57-61_Layout 1 4/6/2020 2:55 PM Page 57

SpecialReport: Drilling Innovations
A case in point is a project onshore
Mexico that incorporated an advanced
point-the-bit RSS with a rugged measurement-while-drilling system to help the
operator drill a very challenging well
through several extremely hard formations
while achieving directional drilling and
wellbore placement objectives. Even with
the overall emphasis on wellbore quality,
the drilling portion of the project was
completed ahead of schedule and below
planned cost. The well was the area's
first horizontal application. It targeted a
Middle Cretaceous formation, and the
geologic conditions mirror those in some
U.S. resource plays with abrasive interbedded formations.

the hardness of the rock, as well as the
variety of rock types throughout the well.
By incorporating an MWD system that
could take resistivity logs while enabling
real-time monitoring of drilling parameters,
the operator sought to overcome the complex downhole drilling environment while
obtaining the information necessary to
effectively place the well as the RSS
geosteered through the lateral.
Optimizing ROP and extending equipment life by having this information were
secondary benefits that further reduced
drilling cost in line with the optimized
BHA design developed by the well planning and engineering analysis team.

Advanced RSS System

Figure 1 shows the well plan, including
the various formations and casing sizes.

FIGURE 1
Well Plan with Planned (Yellow) and Actual (Red) Trajectories
0
Upper Eocene
Middle Eocene

250
Lower Eocene
133⁄8"

500

Upper Paleocene

750

True Vertical Depth (m)

Recognizing that the well's lithology
would prove difficult to drill, the operator
decided to implement a fully automated
closed-loop, point-the-bit RSS to achieve
highly accurate steering in the complex
downhole environment. Another objective
for using RSS was to help reach the
drilling target and producing zone more
effectively while adhering, at minimum,
to planned drilling days. The RSS system
features a functionality whereby it can
be programmed at surface to hit a drilling
target and then effectively left on "cruise
control" until the target changes.
In this project, if the well path deviated
from the targeted zone, the system was
set to autocorrect its course without driller
input, automatically recalculating the trajectory every 96 seconds. This eliminates
the need for data downlinking to change
course or enter a cruise control mode,
which takes additional time.
In addition, incorporating an RSS with
an onboard guidance system enabled the
operator to control inclination and azimuth
via closed-loop communications with
surface and real-time feedback, enhancing
the ability to geosteer and place the well
correctly. The point-the-bit system proved
ideal for this application, where it was
crucial to drill a wellbore devoid of tortuosity and drilling dysfunctions.
The operator incorporated a rugged
MWD system into the BHA design to
provide real-time directional guidance
and geological information through the
problematic curve and lateral sections.
One major challenge in the project was

Case History

The yellow line indicates the operator's
planned trajectory, while the red line is
the actual well. Despite the difficult formations, the trajectory aligned almost
perfectly with the original plan.
Because of the formation's hardness,
conventional tools were not an option for
drilling the curve and lateral. The operator
had encountered extremely poor hole conditions, which were leading to increased
drag on the BHA, wellbore instability
and fluid loss. This was compromising
directional drilling efficiency as well as
persistently decreasing penetration rates,
which were affecting the well's cost versus
the authority for expenditure.
The project began with a comprehensive engineering analysis by teams in
both Houston and Mexico. The teams
examined the well plan, modeled and

1,000

1,250
Lower Paleocene

95⁄8"

1,500

Méndez Shale (Upper Cretaceous)

1,750
San Felipe Formation (Upper Cretaceous)
Agua Nueve Formation (Upper Cretaceous)

2,000

Upper Tamaulipas Formation (Middle Cretaceous)
Final survey at 2,893-m MD

41⁄2"

Projection to the bit at 2,910-m MD

0

150

300

450
600
Vertical Section at 326.12° (m)

750

900

1,050

APRIL 2020 57
American Oil and Gas Reporter - April 2020

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