North Sea: Basol 2000 BDN, An Environmentally Acceptable Alternative

Published: 05/15/2013

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Introduction

A North Sea installation requested M-I SWACO to design a scale dissolver operation for a 7,500 m horizontal oil producer. The target for the scale dissolver job was to secure that wireline tools and perforation gun reached the desired depth. It was predicted that barium sulfate deposits along the wellbore would be an obstacle for reaching the desired depth with tools. The scale dissolver operation was followed by a wireline tool using tractor with mill down to the perforated area at 7,500 m MD to control that the perforating guns could be lowered into the well. Inhibited seawater was used to bullhead the dissolved deposits out in the formation. M-I SWACO was requested to supply environmental friendly chemistry to remove barium sulfate scale in the well.

Product Information

BASOL 2000 BDN is a scale dissolver based on inorganic salts and biodegradable polymers specially designed for North Sea conditions. The product is classified as environmental friendly, biodegradable chemistry. The product can be applied neat or diluted in water prior to use.

Description of the well

This oil producer has previously been scale squeezed 7 times prior to this operation. Due to a long shut in period of the well, the operator suspected barium sulfate deposits along the wellbore and that this could be of hindrance for the wireline tool. The length of well is 8,225 m MD with a 6 inches ID.

North Sea: Basol 2000 BDN, An Environmentally Acceptable Alternative
Figure 1: Well path

Details

CC-TURBOCLEAN was used to clean the deposits along the wellbore to secure better contact between barium sulfate scale and BASOL 2000 BDN. The BASOL 2000 BDN was injected through the kill line using cement unit down to the top of the perforation followed by a 36 hours soak period. After 36 hours, wireline engineers ran a wireline tool containing tractor and mill into the well. At 6,000 meters the pulling weight on the cable decreased as a result of the tractor hitting loose masses. The wireline tool was pulled and it was decided to bullhead the masses out in the perforation using seawater. 350 m3 seawater inhibited with 100 ppm SI-4470 was injected at a rate of 100 m3/h. After the seawater injection, wireline engineers ran the tool down to 7,500 meters without using mill or hitting any restriction in the well. The wireline tractor was pulled and inspected only to contain small pieces of hard materials claimed to be barium sulfate.

Conclusions

This operation demonstrated that BASOL 2000 BDN is a highly effective scale dissolver for barium sulfate scale throughout the wellbore at different temperatures. The environmental friendly BASOL 2000 BDN represents an environmentally acceptable alternative to nonbiodegradable chemistry chelants such as EDTA/DTPA.

Further information

For more details, please contact your local M-I SWACO office.

“Basol 2000 BDN scale dissolver successfully removes barium sulfate (BaSO4) scale in 7,500 m horizontal oil producer.”

Dan Vindenes, Account Manager Well Operations, M-I SWACO

Location
North Sea, Norway, Europe, Offshore
Details

Challenge: A North Sea installation requested M-I SWACO to design a scale dissolver operation for a 7,500 m horizontal oil producer.

Solution: CC-TURBOCLEAN was used to clean the deposits along the wellbore to secure better contact between barium sulfate scale and BASOL 2000 BDN.

Results: Demonstrated that BASOL 2000 BDN is a highly effective scale dissolver for barium sulfate scale throughout the wellbore at different temperatures.