Challenge: The GN-3 Shaker underwent a
field trial on a major operator land drilling site. The main trial objectives
were to test the flow rate handling capacity and make a qualitative assessment
of the solids handling and conveyance capacity of the GN-3 Shaker. Shaker
screen life was also measured and compared to historical benchmarks.
Solution: The GN-3 Shale Shaker is a
multi-deck shaker engineered to provide efficient solid separation. The Shaker Screen
was set in a parallel configuration, meaning the bottom decks were running in
parallel with each other and using the same mesh (for the majority of the
test). For this trial, the GN-3 unit was installed between the shaker cutting
tank and the first fluid storage silo. Tests were conducted on 12-8 and 6-in.
sections.
The GN-3 unit was rigged up to take 100% of
the flow from the bell nipple, with the three rig-owned units on standby, but
isolated. The mud system was KPM, a KCl polymer system. 28 gumbo screens with
0.8 x 118 mm openings were used on the scalping deck and the middle and bottom
decks were dressed with 84 XR screens. HC screens were later used in the
section due to their superior performance in sticky clays. For the first 40 m
(131 ft) drilled, the GN-3 unit was able to handle the complete flow rate of
2,500 L/min. At 40 m (131 ft), the screens partially blinded in unconsolidated
sands and the total flow rate was reduced to 1,250 to 1,500 L/min. The GN-3 unit
was able to handle 750-900 L/min of the total flow (60%). This result was
historically better than previous wells, where flow was usually limited to
<1,000 L/min in total due to excessive blinding across the three rig
shakers. Once into the Breda, Rupel and Asse clay formations the flow rate was
increased to 3,000 to 3,100 L.min in total, with the GN-3 unit treating 2,000
to 2,700 L/min (66 to 88% of total flow). Once into the lower Tertiary clays
and Upper Cretaceous chalk, the GN-3 unit was able to treat up to 3,400 L/min
(100% total flow) with 84/105 (need to specify HC or XR) mesh on the primary
decks.
8?-in. section: After a successful
cementation of the 9 in. casing and the installation of the BOP the section was
started with the GN-3 unit rigged up. The scalping deck was dressed with 38 XL
screens, while the middle and bottom decks were dressed with 165 XR and 165 HC
screens, respectively. The shoe track was drilled out with the previous KPM
water-based mud and then during the drilling out of the cement the well was
displaced to 1.25 SG VCM. Once the mud was displaced, drilling of the fresh
formation started. The mud system was VCM, a VERSACLEAN LTOBM system. From the
beginning of the 8?-in. section the GN-3 unit was able to process the total
flow rate from the well. The flow ranged from 1,600 L/min during rotary
drilling mode, up to 2,200 L/min while drilling in sliding/steering mode. The
GN-3 unit was positioned at the side of the 40 m3 rectangular cutting tank and
with 100% of the flow and a dry discharge, the cuttings were stacked in a small
area and potentially overflowing the cutting tank. Most of the time the
cuttings were manipulated to the sides to keep the shaker running, but at night
the third-party cuttings-moving equipment was not available so flow was
occasionally switched to the rig shakers to spread the cuttings across the
length of the tank.
6-in. section: The 7-in. liner was
successfully cemented and BOP pressure-tested. The section was started with the
GN-3 unit rigged up. During the drilling out of the cement the mud was weighted
up to 1.55 SG. Once the Mud Desilter weight reached 1.55 SG an FIT was performed
and drilling continued. The section was terminated early due to well-control
problems requiring increasing mud weights, and finally requiring a liner to
seal off a high pressure zone. The mud system was VCM., a VERSACLEAN LTOBM
system. From the beginning of the 6-in. section, the GN-3 unit was able to
process the total flow rate. The flow ranged from 500 L/min up to 900 L/min.
The GN-3 unit was positioned at the side of the 40 m3 rectangular cuttings tank
with 100% of the flow and a dry discharge; the cuttings were stacked in a small
area and potentially overflowing the cutting tank. Most of the time the
cuttings were manipulated to the sides to keep the shaker running, but at night
the third party cuttings-moving equipment was not available so flow was
occasionally switched to the rig shakers to spread the cuttings across the
length of the tank.
4 in. section: After the successful running
and cementation of 5 x 5 in. liner at a depth of 3,511 m (11,519 ft) the well
was displaced to VCM mud with a weight of 1.0 SG. Following a positive flow
check and leak off test, drilling ahead was permitted. Drilling ROP was
recorded from 1 to 20 m/hr. One bit trip was required and a fresh bit finished
the well rapidly at a TD of 3,705 m (12,155 ft). The scalping deck was dressed
with 38 XL screens and the middle and bottom decks with 230 HC screens.
The GN-3 unit was able to process the total
flow rate. The flow stayed at 500 L/min for the duration with rotary drilling
mode as there was no MWD tool in the hole.
The GN-3 Shaker handled approximately 95%
of the total fluid flow over the duration of the well. Primary objectives of
the test were met or exceeded, including:
No major QHSE concerns under normal rig
operations
Flowrate handling capacity was measured at
up to 3,400 L/min in the 12?-in. section with 38/84 mesh screens. Capacity was
2,300 L/min in the 8?-in. section with 38/230 to270 screens.
A qualitative assessment of the solid
handling and conveyance capacity showed excellent throughput characteristics Shaker
screen life was measured and compared with historical benchmarks. The coarser
meshes had screen(http://en.wikipedia.org/wiki/Screen) life extending to 120 hr
operating, and the finer meshes showed life spans of up to 120 hr in some
cases.
GN
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