Formate Matters: Issue Nine
Your resource for the latest cesium formate news and industry insights.
Browse through the articles below or download the complete issue.
- The fastest drill in the west +More
- Cabot expands infrastructure +More
- New drilling and completion method cuts Petronas' costs in Malaysia +More
- Beyond oilfield +More
- The heat is on +More
- New people +More
Since June 2013, DMK Drilling Fluids has successfully drilled over 100 wells with potassium formate brine in the Montney shale formation and other unconventional shale fields in western Canada for operators such as Paramount Resources, EnCana, Shell Canada and Progress Energy.
DMK chose solids-free potassium formate brines over invert oil-based muds for drilling long horizontal wells to increase speed and bit life in the hard abrasive shales of Montney. Nick Legacy, DMK Technical Manager, explains: “The benefits of drilling with high-density, solids-free brine have led to significant cost and time savings for operators. These savings come from increased ROP, longer bit life, record bit runs, improved horizontal wellbore cleaning, better casing cement jobs, lower surge/swab pressures, lower ECDs, effective formation inhibition, improved kick detection, ease of use and, most importantly, no corrosion damage.”
DMK uses potassium formate fluid without viscosifiers or fluid-loss polymers in its west Canadian drilling operations. Photo: Courtesy of Blackfox Images/Alamy.
Nick continues: “We have been able to knock days off each horizontal section as well as decreasing the number of bits needed. We typically see ROP improvements of 30 to 50% and bit runs that are consistently twice as long as those with OBMs. We clean and reuse our formate systems from well to well with the same brine system currently being used on over ten consecutive wells and counting”. The team at DMK believes the high thermal conductivity of potassium formate brine compared to oil-based muds provides more efficient bit cooling and might be one of the factors responsible for extending bit life.
Elie Meyer, when working as Senior Drilling Engineer with EnCana, also experienced significant ROP improvements and describes the effect of potassium formate fluid as a “step change” over earlier fluid solutions. He explains: “The fluid is inhibitive. After drilling, caliper logs displayed the same response as invert drilling caliper logs. The ROP improvement allowed us to cut our lateral drilling time in half! We then extended use of this fluid to the intermediate sections as well as the horizontals with similar results.”
Solids- and polymer-free
The secret of DMK’s success is its determination to run potassium formate brine as solids-free drilling fluid, utilising solids-control equipment and flocculants to maintain it in solids-free condition. Also, in a radical departure from convention, DMK uses formate fluid without viscosifiers or fluid-loss polymers. Nick Legacy says: “By using solids- free potassium formate brine to control density, we expose the disadvantages of relying on solid materials to increase fluid density. A fluid designed with a minimalistic rheological profile has many benefits. Fluid flow is almost always turbulent, even at fairly low pump rates, which provides excellent horizontal wellbore cleaning without cuttings beds forming. Having minimal suspension properties allows effective flocculation of solids on surface to maintain our solids-free system. Parasitic pressure losses in the circulating system are greatly reduced, which leads to lower system pressures."
Elie Meyer also notes these effects when working for Encana: “As the formate reduced circulating pressure by 20 to 30% compared to an OBM system at same density and flow rate, there was no need to upgrade the rig to drill the 3000 m laterals.”
Nick Legacy of DMK is optimistic about the future of potassium formate: “We have expanded on our success in Montney horizontals by exploring other areas and formations that may see improvements with the unique range of properties formate brines possess. As these brine systems can be very inhibitive, we have had success drilling intermediate and build sections with our formate mud systems. We are continuing to explore new applications and are testing new products to further improve performance and scope of our formate-based drilling fluids." For more information, visit DMK Performance Fluids.
Potassium formate brine increases drilling speed and reduces costs in abrasive Montney shales.
Following unprecedented demand for cesium formate, Cabot is undertaking substantial investment in both people and plant to expand and optimise its operations.
Nick Cross, President of Advanced Technologies and EMEA in Cabot Corporation and General Manager for Specialty Fluids, explains the increase in use: “Existing customers are placing new orders as they roll out cesium formate-based fluids in multi-well programmes, while using cesium formate brine more often as combined drilling and completion fluids. In addition, new customers are utilising cesium formate for the first time, particularly in challenging HPHT fields. This increased activity is particularly centred in the Norwegian sector of the North Sea and new basins in India, Malaysia and Kazakhstan.” New contracts include a multi-well drilling and completion programme in Valemon, completion operations in Gudrun and perforation and completion in Brynhild. These three fields are located in the Norwegian sector of the North Sea. In addition, Cabot supplies cesium formate for multi-well completions, packer fluids and kill fluids in Malaysia, Brunei and India.
Cabot is recruiting a significant number of experienced field engineers globally, while promoting the most practiced of their current team to senior operational positions. Matt Wood, with previous experience from BP and Cabot, is appointed Product Manager for cesium with responsibility for optimising global operations – including the fine cesium chemicals business – and becomes Site Manager, Aberdeen. Christian Busengdal is promoted to Business Director, North Sea, while retaining responsibility for all operations in Norway. Alan Carnegie is advanced to Director of Global Business Development and APMEA Region with accountability for all business development activity outside the North Sea.
A vital part of Cabot’s strategy is its innovative chemical leasing model and reclamation of cesium formate for reuse in new wells. This sustainable business model reduces operating costs and minimises environmental impact. Building further on this unique approach, financing of new plants in Aberdeen and Bergen give a three-fold increase in global reprocessing capacity, with additional investment in mixing facilities and bulk storage in Norway adding to the improvement in infrastructure.
“As applications for cesium formate increase and our customers’ wells become more challenging, we need infrastructure to meet this demand. I’m confident that our improved organisation and increase in processing capacity, together with other investment, ensures supply and optimal service in the years to come,” concludes Nick Cross.
Petronas has successfully used a new cost-saving technique for drilling and completing gas wells in highly pressured fractured carbonate reservoirs prone to severe circulation losses1–3.
Two wells located 200 km offshore Sarawak were drilled to depths of 1,735 to 1,847 metres True Vertical Depth Drill Floor (TVDDF) in 78-metre-deep water. A 7-inch pre-drilled liner was installed across the deviated (26 – 30 degrees) 100 to 200 metre open-hole sections. Target gas production was 100 MMscfd from each well.
High reservoir pressure called for fluids with equivalent mud weight greater than 1.80 g/cm3/15 lb/gal to maintain well control. The low-solids formate fluids chosen by Petronas needed to:
- Minimize formation damage and ensure maximum gas production rates.
- Minimize the amount of solids passing through gas processing facilities on production start-up.
Low solids, low losses
Previous drilling experience in the area suggested a high probability of losing large fluid volumes to the reservoir while drilling conventionally in overbalance. To minimise fluid losses, Petronas used 1.52 g/cm3/12.7 lb/gal statically and dynamically underbalanced formate drilling fluid in combination with MPD technology to control overbalance through backpressure. The reservoir section of each well was successfully and safely drilled with low-solids potassium formate fluid at 150-psi overbalance with average ROP of 15 – 17 metres/hour without significant fluid losses.
On reaching target depth, the potassium formate drilling fluid was displaced to kill weight 1.81 g/cm3/15.1 lb/gal low-solids formate brine tripping fluid before running the 7-inch pre-drilled liner. The tripping fluid was then displaced to 1.81 g/cm3/15.1 lb/gal clear formate brine for the upper completion. Upper and lower completions were installed in 40 hours and 29 hours respectively with formate completion fluid losses averaging 210 bbl per well. The wells cleaned-up naturally without acidisation using a rapid bean-up method that achieved full clean up within 11 hours. Low-solids loading of formate brines ensured that well test separators were not damaged or blocked by back-produced solids during the clean-up phase.
Multi-rate well flow testing showed that both wells could produce at absolute open flow (AOF) of over 150 MMscfd, which is 50% higher than estimated in the field development plan. These AOF figures compare favourably with AOF of 35 MMscfd achieved from two drill-stem tests on the original exploration well drilled in 2005. An acid stimulation treatment with 15% HCl and gel diverters in one development well (SS-1) was unable to improve gas flow rates or PI, suggesting that formate fluids had already successfully delivered highly-connective wells.
Born to produce
This first-ever deployment of an underbalanced formate brine system for drilling a carbonate reservoir in MPD mode reduced costs and improved safety by:
- Eliminating lost circulation events and associated fluid losses
- Facilitating use of lower-cost, lower-density brine for drilling
- Providing early kick and loss detection
The combination of formate brine and MPD technology improved project economics further by delivering highly productive wells that did not require acid stimulation.References
- IPTC 16697, March 2013.
- IADC/SPE 164573, April 2013.
- SPE 165761, October 2013.
Cesium’s unique properties mean that demand is rapidly growing for use in non-oilfield applications. Excluding francium, cesium has the lowest boiling and melting points, highest vapour pressure, highest density and lowest ionisation potential of all alkali metals, and these important characteristics are directly related to how it’s used.
Magnesium floating on high-density cesium formate brine. Photo: Courtesy of Theodore Gray.
Cabot supplies highly pure cesium in crystalline and solution forms for a wide range of applications as cesium carbonate, cesium chloride, cesium fluoride, cesium formate, cesium hydroxide, cesium nitrate and cesium sulfate.
Cesium use is driven by the economic benefit enabled by improved product performance: fine cesium chemicals enable customers to improve process performance, increase yields, reduce cycle times and prevent or mitigate pollution.
Fine cesium chemicals therefore constitute a small-but-critical component in a wide range of chemical applications, primarily for catalysis and as strong bases in chemical production, such as pigments, polyols and automotive brazing fluxes. They are also used in bio-medical research for DNA/RNA separation, defence products, active pharmaceuticals ingredients and pollution abatement.
Formate brines are unique as they stabilise xanthan gum and other biopolymers to temperatures significantly higher than any other brines1). From the commonly used formate brines, potassium formate stabilises these polymers to the highest temperature – 16 hours at 200°C/392°F2).
However, as the oil and gas industry moves towards ultra and extreme HPHT jobs, there is a need to push the temperature limit even further. Consequently, a study was completed to identify synthetic polymers compatible with formate brines that perform under such extreme temperature conditions. Synthetic polymers used in drilling fluids are very different from common synthetic polymers used in everyday life, such as plastics, rubbers and nylons as they are mostly water soluble. The main types of synthetic polymers used in drilling include polyacrylate, polyacrylamide, 2-(acrylamide)-2-methylpropanesulfonic acid, cationic polymers, copolymers and ter-polymers.
A total of ten synthetic polymers from several suppliers were screened for viscosity stability. These synthetic polymers were added to a cesium/potassium formate brine blend together with xanthan gum. The xanthan gum performed two functions. Firstly, it contributed to initial fluid viscosity before it broke down after several hours at very high temperatures. Secondly, it helped to disperse synthetic polymers before they started hydrating.
Two polymers – HE100 and HE150 supplied by Drilling Specialty Fluids – showed outstanding performance during testing. These polymers were statically aged in cesium/potassium formate brine for 64 hours at 250°C/482°F with no degradation. In fact, the polymers actually showed signs of slightly increased hydration during the final period of temperature exposure. Cabot is unable to test polymers above 250°C, but is optimistic that the temperature ceiling is much higher.
Allan Grossart, 45, joins Cabot as a regional technical service manager.
Previously, he worked 12 years for Total and four years for Baker Hughes, lastly as European Marketing Manager for Drilling Fluids and Upstream Chemicals. Allan says: “The new role with Cabot gives me the opportunity to build on and utilise my experience and expertise to identify opportunity areas for cesium formate, create sustainable growth and play a key role in delivering high standards of customer service.”
Allan is married with two children aged one and four. He has a PhD in Chemistry from the University of Cambridge and enjoys golf, cinema and travel.