0 1 2 3 4 5
Productivity Index Comparison in the West of Shetlands Area
10 15 20 25 30
Average PI = 1.5 5 0 -5 Production wells Production slot s > Productivity index and skin comparison. After the new completion that included the MudSOLV
ltercake cleanup service, ClearPAC uid system, the QUANTUM packer and the AllPAC screen system, the P110 well performed much better than the majority of the wells in Foinaven eld. It exhibited a higher productivity index (left) with a skin of zero (right). The productivity index comparison was made on 35 production slots, while the skin comparison was made on 28 production wells. In this case, production slots and production wells are not comparable.
Clay Volume 0
Porosity vol/vol 1
01 05 psi vol/vol 106 psi 0 Poisson’ s Ratio
Young’s Modulus 0.2
0.5
Unconfined Compressive Strength
Principal Stress X Principal Stress Y Principal Stress Z Pore Pressure
20,000 8,000 psi 18,000 Sand 0
Critical Drawdown Pressure psi
Safe Drawdown 20,000 X,500
technology, proper planning and an integrated approach to sand management resulted in suc- cessful packing of the entire interval. The new completion design in the Foinaven field performed extremely well compared with the average performance of more than 30 hori- zontal wells in the West of Shetlands area, for both oil production and sand-control effective- ness. An early buildup test revealed not only a zero skin compared with a 28-well average skin of +4.8, but also a higher productivity index (above). During the initial production test, the P110 well showed a rate of 20,500 B/D [3,260 m3/d] with a fully open choke. This was attributed to improved sand control and the reduced damage associated with the drilling and completion operations.
X,000 Testing Weak Sands X,500 G zone X,000 X,500 X,000 I zone
> Critical drawdown log for Trident Well 1. The data from the Trident Well 1 indicated that the Wilcox G zone is a serious risk because of potential formation collapse when exposed to excessive drawdown levels during MDT testing and sampling. The Wilcox I zone was substantially more competent. Clay volume and porosity are displayed in Track 1, computed Poisson’s ratio and Young’s modulus are presented in Track 2, calculated uncon ned compressive strength (UCS) is shown in Track 3, and the computed principal stresses and pore pressure are displayed in Track 4. Track 5 shows the critical drawdown pressures calculated from the sand-prediction modeling tool.
24
New applications for predicting sand failure con- tinue to emerge with the growing understanding of the relationship between stresses, reservoirs and completions. Operators evaluating deep- water wells in the Gulf of Mexico rely on a variety of downhole measurements to determine reser- voir characteristics, potential reserves, required production facilities and asset-development strategies. In many deepwater fields, the MDT tool has become a crucial provider of important reservoir information. Using this device, an oper- ator can determine reservoir pressure and permeability, evaluate whether the reservoir is damaged, and collect and analyze representative fl uid samples.33
In one of its many configurations, the MDT
tool deploys a small packer and probe device that presses against the borehole wall, isolating the probe from hydrostatic pressure so that forma- tion pressure can be measured. In weak or unconsolidated formations, the probes can become clogged, hindering testing and sampling. Depending on the specifi c well and reservoir, a dual-packer assembly may be preferable in weak
Total Skin Comparison in the West of Shetlands Area
Average skin = +4.8
Oilfi eld Review
Initial productivity index (PI) Measured depth, ft
P13 P17 P15 P16 P18 P21 P22 P24 P25 CP01 CP03 LP01 P23
WP02 CP05 CP02 CP09 LP03 CP08 WP03 CP06 P14
WP01 WP07 P26 P12 CP04 P11 CP07 P28 P41 P29 P210
P110 CP14
Skin
P15 P13 P17 P18 P22 P21 P25 P27z P24 P28 P41 P29 P210 P27y
C01 C03 C06
C07
C05 W02 L01 C11 C10
W05 W04 C12x C13
P110
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