News | February 22, 2018

Operator Achieves Optimal Hole Cleaning Using Two DAV MX CircSubs In Single Drill String

  • European operator boosts annular velocity in a challenging geothermal well and cuts hole cleaning time by 75% by running two CircSubs
  • Operator achieves significant increase in cuttings returns activating DAV MX CircSubs 

Churchill Drilling Tools, a leading oilfield service company specializing in drilling innovation, is partnering with operators to significantly improve hole cleaning and project performance by using its flagship DAV (Dart Activated Valve) MX CircSub.

Operators are increasingly recognizing the specialist support Churchill Drilling Tools delivers and the value the DAV MX brings when deployed in pre-planned activities as a cost effective method of hole cleaning and performance optimization.

The DAV MX’s resilience, versatility, speed and reliability, which are enabling clients to cut operating time, was put to the test recently by a European operator in a challenging onshore geothermal well in the Netherlands.

Optimal hole cleaning was essential given the challenging multi-tapered casing profile of the string.  By deploying two DAV MX CircSubs, the operator boosted annular velocity and optimized its hole cleaning process across two separate runs.  It cut the time to transport cuttings to the surface by around 50% if using a single CircSub and 75% if no CircSub was in the string.  In optimizing the hole cleaning process the operator also prevented any concern of managing a stuck pipe situation.

During the first 6” section drillout run the operator activated the lower DAV MX, positioned in the BHA, providing an annular velocity boost and flushed cuttings to above the 9 5/8” x 7” liner. The client then activated the upper DAV MX, placed higher up the drill string, to lift the cuttings to surface before cycling back to its closed position. The same sequence was carried out during the subsequent 6” x 8 1/2” hole enlargement run using another two CircSubs.  In total, four DAV MX CircSubs were successfully activated across the two runs.

The client said it was pleased with the DAV MX’s performance and observed a significant increase in cuttings returns after each activation.

The operator also used the lower placed CircSub’s unique lock open feature on each run for dry tripping, achieving safer rig floor conditions and cutting tripping out time. 

As always, the operator had a big safety margin because of the DAV MX’s Emergency Shut-Off Dart (ESD), a unique fail-safe feature used on the rare occasions an operator has to push beyond the performance envelope and the valve becomes damaged.  As usual, it was not deployed, but knowing the ESD could seal any leak paths, maintain thru-bore and allow the programme to continue without pulling out of hole, gave the operator additional confidence to complete an ambitious by-pass strategy.

Churchill’s European regional account manager, Corin Lewsey, said: “We’re pleased our DAV MX CircSub continues to help operators drill faster, more efficiently and at low risk. 

“In this case, the operator demonstrated that running two CircSubs in the string can be a more reliable and effective method of hole cleaning and saves significant rig time.  In 2018 we expect to see this trend increase significantly, especially among the many operators across the globe who are already running one DAV MX and benefiting from the tool’s simplicity, speed and reliability.”

In 2017 operators carried out more campaigns running the DAV MX than ever before.  Churchill is also seeing more of its CircSubs deployed in geothermal wells. Last year, the DAV MX was successfully deployed in the world’s deepest and hottest borehole, in Iceland, at a depth of 4,659m and 427º.

Corin continued: “Geothermal wells are an area of expansion for us and reflects the DAV MX’s ability to withstand even the most challenging of environments.  There is no other tool available that can match the resilience of our CircSub.”

He added: “More and more operators are benefiting from the value our DAV MX CircSub delivers across a wide range of applications and especially when deployed on a pre-planned basis.  The growing demand confirms the quality of our tool, our customer performance and the trust and confidence the industry has in our products.”

Churchill’s tools have the widest operating envelope in class.  Supported by the company’s experience, customer performance, quality and capability, Churchill’s smart dart activated DAV MX is a multi-functioning, multi-cycling circulation sub that delivers significantly improved performance and is simple to use. Fast, versatile and reliable, it can be run in most environments and in a wide range of applications.

SOURCE: Churchill Drilling Tools