30-in. casing at 288 ft MD 30-in. casing at 310 ft MD
13 3⁄ 8-in. casing at 5,185 ft MD 13 3⁄ 8-in. casing at 5,350 ft MD 7,688 ft MD 8,300 ft MD H-IA H-IA 9 5⁄ 8-in. casing at 8,473 ft MD
H-IIA H-IIB
10,152 ft MD
H-IIC H-IID H-IIE
H-IIA H-IIB
H-IIC H-IID H-IIE H-IIF
9,098 ft MD 9,255 ft MD 9,255 ft MD 7-in. liner at 7,867 ft MD
9 5⁄ 8-in. casing at 7,870 ft MD
> Selective lateral access. In the UAE Upper Zakum eld, ZADCO needed to reenter two multilateral wells. The rst well, drilled and completed with dual tubing, produced from four openhole laterals (left). The short string produced from a lateral in Reservoir H-IA, and the long string produced separate laterals in Reservoirs H-IIB, H-IIC and H-IID. ZADCO selectively acidized the H-IIC lateral using a Discovery MLT tool. The second well also had dual tubing (right). The short string produced a horizontal lateral in Reservoir H-IA. The long string produced from horizontal laterals in the H-IIC, H-IID, H-IIE and H-IIF reservoirs. ZADCO selectively acidized the H-IID and H-IIE laterals with a Discovery MLT tool.
tool in the UAE.22
Multilateral completions in the
Upper Zakum field tap several reservoir layers with as many as 12 laterals drilled from a single main wellbore (above). Previously, remedial access to individual branches was not possible, which prevented effective stimulation and production logging of individual laterals to evaluate treatment results and monitor production. Acid had to be bull- headed— pumped from surface— down wellbore tubulars or coiled tubing with the end of pipe near a lateral entrance.
The majority of the acid reaction occurred at
the entrance of the openhole section, leaving the remainder of the lateral branch untreated. This
practice also created large voids that could col- lapse and prevent future access to the lateral or restrict production. ZADCO successfully acidized openhole laterals in two offshore wells using Discovery MLT technology. In the fi rst use of this tool, ZADCO performed a selective treatment in one lateral of a well with four branches. In a second well, two of the fi ve laterals were treated individually. These jobs took seven days— four days of operations and three days of mobilization, demobilization and weather delays— and cost 65% less than using a drilling rig. Production increased by 11% in the
fi rst well and 30% in the second well, which paid back the investment in two days.
The Discovery MLT tool has proved to be a simple, cost-effective lateral reentry solution that helps maximize the productivity and performance of multilateral wells. In another UAE well for a different operating company, the Discovery MLT system helped selectively cement a lateral and shut off water production utilizing coiled tubing. In Oman, Petroleum Development Oman (PDO) successfully performed production logging in a Saih Rawl fi eld multilateral well.23
PDO selec-
tively reentered and logged three lateral branches to determine the water-injection profi le and identify possible fractures in the formation.
54
Oilfi eld Review
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76