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FORMATE BRINES. John Downs Consultant. Formate brines. Formates are also soluble in some non-aqueous solvents. Formate Brines – Properties. Formates allow a choice of solvents – water is the most common Density up to 2.3 g/cm 3 (or 2.45 g/cm 3 with acetate)
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FORMATE BRINES John Downs Consultant
Formate brines Formates are also soluble in some non-aqueous solvents
Formate Brines – Properties • Formates allow a choice of solvents – water is the most common • Density up to 2.3 g/cm3 (or 2.45 g/cm3 with acetate) • Monovalent ions (Na+, K+, Cs+, HCOO-) • Slightly alkaline pH : 9-10 • Low brine viscosity • Non-toxic and readily biodegradable
Solubility of cesium formate in various solvents The cesium-weighted MEG makes an interesting non-aqueous drilling and completion fluid for HPHT wells
Formate Brines – Driver for their discovery Early 1980’s – Shell was developing xanthan gum viscosifier for drilling fluids and EOR . Needed a stabiliser to protect it at > 120oC
Formate brines – Discovery and qualification by Shell Research Shell discover cesium formate brine Start of Shell’s deep slim-hole drilling R&D programme Shell patent the use of formates as polymer stabilisers Shell publish first SPE papers on formate brines 1992 1991 1987 1988 1989 1990 Shell R&D in UK study the effect of sodium and potassium formates on the thermal stability of drilling polymers Shell R&D in The Netherlands carry out qualification work on formate brines as deep slim-hole (HPHT) drilling fluids
The main application for formate brines is in high-pressure high-temperature gas wells Low-solids heavy fluids for deep HPHT gas well constructions • Reservoir drill-in • Completion • Workover • Packer fluids • Well suspension • Fracking Used in hundreds of HPHT wells since 1995, including some of Europe’s deepest, hottest and highly-pressured gas reservoirs
The economic benefits provided by formate brines in HPHT gas field developments Formate brines improve the economics of HPHT gas field developments by : • Reducing well delivery time and costs • Improving operational safety and reducing risk • Delivering production rates that exceed expectations • Providing more precise reservoir definition
42deep HPHT gas fields developed using formate brines , 1995-2011. Now probably > 50 fields * * More HPHT fields developed in Kuwait, India and Malaysia during 2012-2013
Formate brines – Production and first field use - Milestones Start of deep HPHT gas well drilling with formates in Germany (Mobil, RWE, Shell) Potassium formate brines used in USA, Canada, Mexico, Venezuela, Brazil, Ecuador First field use of sodium formate: Shell drills and completes first Draugen oil wells First field use of potassium formate (with Micromax) : Statoil drills and completes Gullfaks oil well First use of formate brine as packer fluid: Shell Dunlin A-14 1998 1997 1993 1994 1995 1996 Sodium formate powder available. Draugen wells each produce 48,000 bbl oil /day 1994 - Potassium formate brine becomes available from Addcon 1997 - Cesium formate brine becomes available from Cabot