Bunga Kekwa-Raya Fields

CASE STUDY
Bunga
Kekwa-Raya
Fields
Project Context
& Description:
Talisman Malaysia Ltd.
(TML) operated Block PM-3
CAA offshore eastern Malaysia, which is about 240
km northeast of Kertih, Terengganu. Over six wellhead platforms were installed to develop the Bunga
Kekwa-Raya Fields. The first development was in
2002 with the installation of Bunga Kekwa-A (BK-A)
platform with 10 wells. Subsequent field development plans installed Bunga Kekwa-C (BK-C), Bunga
Raya-B, Bunga Raya-C and Bunga Seroja-A wellhead
platforms to drill more wells of various utilities. Development drilling was carried out using the contracted jackup drilling rigs Harvey H. Ward and Roger W.
Mowell . Both rigs are identical in size and equipment
capability. TML drilled more than 100 km of 12 ¼”.
hole in over 60 development wells.
12 ¼” hole section associated with borehole cleaning.
In 12 ¼” holes, common values of flow-rate, combined with mud properties and drill string rpm, usually
maintain laminar or transitional mud flow.
However, in areas with cuttings dunes, at flow-rates
above 1,000 gpm and 110 rpm, the flow can become
turbulent and significantly increases pressure losses.
Typical well profiles include build-and-hold and holdand-drop (S profile) with inclinations up to 70° and
open-hole sections ranging from 1,000 meters to
2,500 meters. These wells were drilled with syntheticbased mud and a steerable assembly using standard
5”. drill pipe and 8”. drill collar in the BHA. Often, the
trip out from total depth was difficult due to numerous
tight spots, most likely caused by cuttings beds.
Reservoir targets in PM-3 area are of Middle Miocene
and Lower Miocene age with reservoir depths ranging
from 1,600 meters Total Vertical Depth to 3,000 meters
Total Vertical Depth. The stratigraphy of the Malay Basin
consists of a monotonous section of shales, sands
and coals, nearly all deposited in coastal plain to shallow
marine environments. Wells drilled in the PM-3 area
encountered normal or near-normal pressure regimes
with normal temperature gradient.
TML realized the importance of effective hole cleaning
to mitigate stuck-pipe incidents. The majority of BK-A
wells encountered frequent hole problems in the
Challenge:
Drilling dysfunctions experienced in 12 1/4” holes
difficulties tripping the drill string
in & out of hole
inefficient hole cleaning
excessive and erratic drilling torque
tight hole and stuck pipe events
Low drilling Rates of Penetration
less than optimum Rate of Penetration (ROP)
excessive Non Productive Time (NPT)
time spend not drilling
Difficulties running casing
pulled casing out of hole
O ffshore
Hydroclean®
Vallourec
Solution:
The profile’s HBZ protects the wellbore from the blades and provides optimized sliding properties, due to
the hardbanding’s low friction profile.
The conical design decreases friction from a fluid
bearing effect between the pipe and wellbore.
High velocity zone
of annular passage
Hydroclean®
recirculating
zone
Final cutting
bed height
Q
Ω
Dynamic recirculation
Two zones of full scooping
and lift of cuttings
Initial cutting ROP
bed height
Negative blade angles provide optimum scooping.
The conical design decreases friction.
Results
& Benefits:
Hydroclean® improved performance
in 4 key performance indicator categories:
cleaning efficiency
• increase cutting size indicator +14%
• decrease circulating time indication -52%
well bores quality & stability
• decrease in back-reaming time indicator -75%
20 hours or 11% operating time saved for
7 days of drilling.
time savings
• decrease in tripping time -49%
operational safety
• decrease in TD friction factor -60%
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Hydroclean® upset consists of two
distinct zones: the Hydro-Cleaning
Zone (HCZ) and the Hydro-Bearing Zone (HBZ).
When combined with flowrate and pipe rotational
speed, the bladed upsets improve hole cleaning in
the drilling and tripping phase.
The negative angle of the blades provides optimum
scooping, while the variable helix angle accelerates
the lifted particles and recirculates them into the
hole’s maximum fluid velocity zone.