| Authors |
K. M. Al-Naimi, B. O. Lee, S. M. Shourbagi, Saudi Aramco, S. K. Kelkar, M.
Shaheen, Schlumberger, B. Johnston, Packer Plus Energy Services
|
| Preview |
Abstract
Horizontal completion technology has progressed dramatically over the last six
years, with the latest technical barriers being eclipsed with open-hole
technology. These completions have allowed multiple zones to be fractured and
the benefits of utilizing open-hole horizontal completion technology have been
well documented. The efficiencies and benefits of utilizing open-hole
completion with mechanical isolation, has lead to the operational benefits of
multiple fracturing operations being pumped in one continuous operation
equating to time savings, more efficient fractures, faster cleanup and less
safety hazards. Conventional methods of cementing a liner in place,
perforating, fracturing and repeating the process for the number of stages
required can be very time consuming with added expense of removing the frac
plugs with coiled tubing after the operations have been completed.
When drilling a horizontal well, there are two preferred completion options.
First, the horizontal section can be completed open-hole or with
slotted/preperforated liner. In these completions effective stimulation along
the horizontal wellbore is almost impossible. The second completion system,
cased/perforated liner, requires cementing the production liner and running
multiple isolation systems to effectively treat different sections of the
wellbore. Multiple coiled tubing trips and multiple rigup and rig-down of the
stimulation equipment is required. These multi-stage horizontal completions
take weeks to complete at high costs and elevated risks. Ultimately, the high
completion costs or the lack of production due to ineffective stimulation make
many reservoirs uneconomical to exploit.
This paper will discuss the new completion designed specifically for open-hole
fracturing of both sandstone and carbonate reservoirs. This innovative, field
proven system greatly increases the effectiveness of fracturing operations by
segmenting the lateral and producing mechanical isolation points in the
wellbore using the high performance open-hole packers. The system allows
precision placement of fracturing fluids to maximize post-fracture productivity
of the well. The completion system is run as part of an uncemented liner and
spaced out based on the required number of stages. Once in place the packers
are hydraulically set and fracturing treatments are pumped in separate stages
but as a single continuous operation. By eliminating cementing requirements,
natural fractures are undamaged and easily stimulated during pumping
operations.
Introduction
Over the last two decades many developments have enabled an accelerated growth
in horizontal drilling. Current drilling technologies have pioneered these
advancements to such an extent that drilling thousands of feet through a thinly
bedded hydrocarbon reservoir is not a challenge anymore. While horizontal
drilling has progressed over the last decade to become the field development
method of choice, in many cases, there have been certain limiting technologies
on the completion of horizontal wells that have proven to slow that growth.
This is primarily the ability to effectively stimulate or fracture different
intervals of the horizontal wellbore, particularly in reservoirs that are not
naturally fractured. The use of limited entry and bullheading techniques
provides little, if any, benefit compared to vertical wells. Post production
analysis on the deliverability
of horizontal wells in reservoirs such as matrix, heterogeneous and
non-conventional formations showed a direct correlation to the completion and
stimulation methods employed and their shortcomings in horizontal applications.
Thus, the additional economics required to drill a horizontal well was not
justified by the equal to or slightly better production results compared to
vertical wells.
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