Schlumberger

Performance Report: GLYDRIL-IDCAP D System Successfully Drills Reservoir, Offshore Vietnam

Challenge: Wells in the Rang Dong Field have produced a significant amount of sand during the last few years from a reservoir of inter‐bedded sand‐silt‐shale. The formation has up to 30% clay minerals content with wide ranging permeability and sand particle size. A sand control screen is required to prevent sand production.

Solution: An inhibitive water‐base reservoir drill‐in fluid (RDF) was needed to drill the reservoir section to minimize sand screen plugging resulting from clay swelling and dispersion, as well as provide good hole integrity. The GLYDRIL‐IDCAP D system was chosen since it could provide good inhibition while maintaining good filtercake cleanup efficiency using 10% HCl. From 40 to 50 lb/bbl (114 to 143 kg/m3) sized calcium carbonate was used to minimize invasion and formation damage. RDF quality control checks were routinely performed aboard the rig while drilling the reservoir section.

Result: The system performed as expected, with a total of 433 m (1420 ft) of reservoir horizontally drilled with no hole‐related problems. The operator achieved the expected production rates and proclaimed the well a 100% success.

Well Information
Location Rang Dong Field, Offshore Vietnam
Spud/completion August 2004
Interval drilled 8½‐in. horizontal hole for a total of 433 m (1420 ft) – from 2410 to 2843 m (7907 to 9327 ft)
Disposal method Discharged cuttings overboard

Extensive laboratory testing was performed prior to the drilling and completion of the well. Shale inhibition and solids contamination tests were done at the M‐I SWACO Regional Laboratory in Jakarta. Filtercake cleanup efficiency was evaluated and extensively tested at Constien & Associates Laboratory in Oklahoma, USA.

The GLYDRIL‐IDCAP D system was chosen since it could provide good shale inhibition while maintaining good filtercake cleanup efficiency with 10% HCl. A total of 433 m (1420 ft) of reservoir section was drilled with no hole‐related problems.

The initial dilution rate was 1.65 bbl/m (0.50 bbl/ft) drilled. The dilution rate was increased to 3.0 bbl/m (0.91 bbl/ft) drilled during the last 140 m (459 ft) because the formation being drilled was primarily siltstone. Dumping and dilution were performed simultaneously to keep the fluid properties within specification.

Although four VSM shakers, dressed with 185‐mesh DURAFLO screens, were available, only two were used while drilling the reservoir section. These two shakers could handle a 600‐gpm flow rate.

A 1.15‐sg (9.6 lbm/gal) filtered KCl brine was used as a completion fluid. The sand screen was set in place as programmed. Filtercake cleanup was performed twice with a 10% HCl solution. A 1.03‐sg (8.58 lbm/gal) filtered KCl brine was used as a packer fluid.

RDF Formulation:
Drill water as required
Soda ash 0.5 lb/bbl
KC1 10% w/w
GLYDRIL MC 3% v/v
IDCAP D 3.0 lb/bbl
FLO-VIS PLUS 1.5 lb/bbl
FLO-TROL 7.0 lb/bbl
SAFE-CARB 2 - 10.0 lb/bbl, CaCO3 Fine - 25 lb/bbl and SAFE-CARB 20 - 25 lb/bbl
Dilution: CaCO3 F - 30 lb/bbl & SAFE-CARB 20 - 30 lb/bbl
RDF Properties:
Fluid density 1.17 – 1.18 sg
6-rpm dial reading 11 - 14
API FL 3 – 4 mL
QAQC checks (every 2 – 3 hours):
Drill solids max 1.6%
MBT max 1.25 lb/bbl
CaCO3 47 – 55 lb/bbl
PPA test using 35μ ceramic disk (500 psi @ 200°F)
Spurt loss 1.2 – 2.4 mL
Actual 30-min 5.0 – 8.6 mL

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“The GLYDRIL-IDCAP D system was used to successfully drill an 8 ½-in. horizontal reservoir section, offshore Vietnam as programmed. The well was completed open-hole with a stand-alone sand screen.”
F. Huadi
Operations Engineer – Tech Support