English Edition (6 MB pdf) - Saudi Aramco

Leveraging Slim Hole Logging Tools in the
Economic Development of Ghawar Field
Authors: Izuchukwu Ariwodo, Ali R. Al-Belowi, Rami H. BinNasser, Robert S. Kuchinski and Ibrahim A. Zainaddin
ABSTRACT
Traditionally, brown field developments have often required
the plug back and sidetrack of existing drain holes, to target
any nearby opportunities. With advances in drilling tech -
nology, there is a general preference to drill small diameter
wells due to the comparative cost advantage.
In recent times, this preference has led some wireline service
companies to start to offer open hole formation evaluation
services with slim tools having a diameter in the 2” to 2½” range.
At present, most of the traditional petrophysical measurements
can be acquired utilizing slim tools. In addition, several
“specialized” measurements, such as cross dipole sonic, formation
pressure testing, and resistivity imaging can also be acquired. The
use of battery and memory technologies has allowed these tools
to be deployed using a broader range of conveyance techniques
allowing for reduced risk in the entry of slim hole wells.
The provision of slim hole logging services has created an
opportunity in the industry to leverage these tools for the
economic development of brown fields. Therefore, short
horizontal sidetracks and well reentries to test deeper horizons
can be drilled and logged successfully. Saudi Aramco has been
able to leverage these tools in its continued development of
the giant Ghawar field. Some of the development projects are
listed here:
• Some horizontal sidetracks with 3 7 ⁄8” hole sizes have
been drilled under higher doglegs than was previously
possible, and logged successfully.
• It is now possible to run well completions in newly
drilled wells that have a well control problem. A
provision is made to subsequently log these wells with
slim wireline logging tools.
• It is now possible to run a complete suite of wireline logs
across some old wells that were previously completed
without a full formation evaluation logging suite.
• Slim hole formation resistivity imaging services are now
being provided, to aid in the identification of borehole
breakout and fracture features that might affect the
well’s productivity.
• Slim hole formation pressure testing has been acquired
in slim hole wells to generate a pressure gradient,
determine oil mobility, and define oil-water contacts.
Several case studies will be used in this article to
demonstrate how Saudi Aramco has leveraged these slim
wireline tools to realize some development opportunities.
Also, examples will be used to show that these slim tools do
not compromise the quality of log data acquisition.
INTRODUCTION
Saudi Aramco has been producing oil and gas from its giant
fields for over 70 years. Over this time, some of these giant
fields have been developed to such an extent that they have
matured into brown fields. As is done with most brown field
development, Saudi Aramco engineers are continuously
striving to push and extend the economic productive life of
these fields, by the deployment of cost-effective, low risk
technologies.
One such cost-effective measure employed by Saudi
Aramco engineers is the workover reentry of some existing
producing wells, either to re-complete the next zone in the
well, or to sidetrack and extend the well’s reach to an existing
attic fluid elsewhere in the reservoir subsurface structure.
Sidetracking an existing well is often challenging, as it
requires the drilling of hole sizes smaller than the well
diameter at the sidetracking point. As a result:
• Because of hole size limitations, the sidetracking point is
often determined by the expected hole size of the final
target horizon. The well path is therefore planned from
the total depth (TD) to the sidetrack point back to the
motherbore.
• Drilling bottom-hole assemblies (BHAs), which were
generally large in diameter, do not allow for flexibility
in building angles fast.
• There is a high incidence of stuck pipes associated with
attempts to drill holes smaller than 5” in diameter.
• Special completions, like the slim smart completion
(SSC) could not be deployed in slim holes, due to
tubular and completion equipment size restrictions 1 .
This problem has since been mitigated with the
technological advancements in drilling and completion
engineering, which has opened the scope for drilling holes
smaller than or equal to 5”. As a result of these advance -
ments, petroleum engineers have found a high value from the
58 SUMMER 2010 SAUDI ARAMCO JOURNAL OF TECHNOLOGY