Troublesome Formation Offshore Vietnam is No Match for ULTRADRIL Mud System | Schlumberger
Case Study
Location
Vietnam, Asia, Offshore
Details

Challenge: A joint operating company was looking for a high-performance water-base mud system to replace the silicate mud that has been used for a few wells.

Solution: M-I SWACO engineers re-introduced the high-performance ULTRADRIL mud system to this operator based on good performance of this fluid in the many wells in Vietnam drilled for other operators.

Results: Two wells were drilled successfully and trouble free.

Products Used

Troublesome Formation Offshore Vietnam is No Match for ULTRADRIL Mud System

Well Information  
Location Offshore Vietnam
Interval drilled 12 1/4-in. hole for 966 m (3169 ft) total depth (TD)
Interval drilled 8 1/2-in. hole for 1640 m (5381 ft) TD
Disposal method Discharged cuttings overboard
Mud weight 10.5 lb/gal
Completion/testing type NaC1 brine
Bottomhole temperature 130°C (266°F)
Water depth 79 m (259 ft)

The Situation

A joint operating company was looking for a high-performance water-base mud system to replace the silicate mud that has been used for a few wells. Equipment failures and torque issues were some of the drivers for this change and a highly inhibitive mud system is always preferred to drill in the reactive Bach Ho shale formation. The mud system also needed to be suitable for coring purposes.

The Solution

M-I SWACO engineers re-introduced the high-performance ULTRADRIL mud system to this operator based on good performance of this fluid in the many wells in Vietnam drilled for other operators. The operator showed some hesitation to run the ULTRADRIL mud system because of previous performance concerns; post-project investigation showed that drilling practices and poor hydraulics caused the performance problems. Following review of worldwide performance and the benefits of the ULTRADRIL system, the operator approved use of the fluid and the opportunity to prove fluid performance in this environment under the right drilling conditions.

The Results

Two wells were drilled successfully and trouble free. Casings were set on bottom with no problems, coring and all logging data was acquired successfully.

The mud system worked well in conjunction with running the PDC bit. Cuttings at the shakers were observed to be well-consolidated. There was very little indication of cavings while drilling the interval. Good penetration rates were achieved and the mud provided good hole cleaning throughout the interval. There was no indication of pipe sticking or friction.

The Details

High performance from this mud system significantly contributed to the success of drilling these two wells. The wells were drilled from two rigs with no mud-related problems. The operator agreed that ULTRADRIL fluid proved to be the right solution for replacing the silicate mud system that had been used on a number of previous wells. Superior inhibition and better rate of penetration was achieved in addition to less downtime from equipment failure due to the nature of silicate.

Lessons learned from the first project well emphasized the benefit of maintaining the key products at optimum level concentration throughout the drilling program.

12 1/4-in. section Well 1 Well 2 Well 3 Well 4 Well 5
Length, meters (ft) 2136 (7008) 2311 (7582) 1754 (5755) 966 (3169) 1575 (5167)
Mud type Silicate Silicate Silicate ULTRADRIL S/W - Gel
Mud weight, lb/gal 10.5 10.2 10.3 10.5 8.8
Volume built, bbl 7186 4930 4204 3276 8455
Volume used, bbl 3972 5368 4154 1186 8455
Dilution rate 1.9 2.3 2.4 1.2 4.5
8 1/2-in. section Well 1 Well 2 Well 3 Well 4 Well 5
Length, meters (ft) 170 (558) N/A N/A 683 (2241) 1640 (5381)
Mud type Silicate N/A N/A ULTRADRIL ULTRADRIL
Mud weight, lb/gal 10.4 N/A N/A 10.0 10.2
Volume built, bbl 368 N/A N/A 869 3319
Volume used, bbl 1378 N/A N/A 2959 3319
Dilution rate 1.8 N/A N/A 0.9 1.3

Average Concentration of Key Products

Product ULTRADRIL in 12 1/4-in.  ULTRADRIL in 8 1/2-in.
ULTRAHIB 3% 3.5% v/v
ULTRACAP 2.8 lb/bbl 3.0 lb/bbl
ULTRAFREE 1% v/v 2% v/v
“ULTRADRIL* fluid has proven to be very suitable for drilling offshore Vietnam on both performance and environmental fronts as compared to a silicate system.”Randy Lydda, M-I SWACO Project Engineer

Questions? We’ll be glad to answer them.

If you’d like to know more about the ULTRADRIL system and how it’s performing for our other customers, please call the M-I SWACO office nearest you.

Products Used

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