Stimulation of Sandstone and Carbonate Reservoirs Using Chelating Agents Amin Ameri amin.ameri@akzonobel.com October, 2016
Major problems with carbonate acidizing
Major problems with sandstone acidizing
Chelates StimWell Portfolio Dissolvine StimWell is a chelate based product series Dissolvine StimWell HTF (ph 3.8): CaCO3 Iron scales Dissolvine StimWell DGH (ph 11.5): CaSO4 Dissolvine StimWell DDH (ph 14): BaSO4 SrSO4
Summary GLDA ASDA EDG MGDA HEDTA MSA HCl Solubility ph<4 ++ + - - +/- ++ ++ Calcite dissolution + +/- - - + ++ ++ Carbonate (300 F, 2cc/min) * Dependent on T and flow rate conditions ++ + - - + -* -* Sandstone ++ +/- - - + n.d. - Thermal stability + - ++ ++ + ++ ++ Corrosion L-80 + +/- +/- +/- +/- - - Corrosion Cr-13 ++ + + + +/- - - Health ++ ++ ++ ++ ++ - - Biodegradability (OECD 301D) Solubility in 15% HCl ++ ++ ++ ++ - ++ n.a. ++ - + +/- ++ n.d. n.a. Iron control + + ++ +/- ++ n.a. n.a.
Low corrosion profile 1.00 0.90 0.80 GLDA HEDTA Coupons fully dissolved 6-hours metal loss (lbs/sq.ft) 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 0.0009 20wt% GLDA 0.0011 10wt% Citric acid 0.0318 10wt% Acetic acid 0.0900 20wt% MGDA 0.5253 20wt% HEDTA 10wt% 15wt% HCl Formic acid Cr-13 300 F N 2 head space 6 hour metal loss at temperature
Low corrosion profile 6-hour metal loss (lbs/sq.ft.) 1.2 1 0.8 0.6 GLDA Acetic Coupons fully dissolved No CI 0.001v% CI 0.4 0.2 0 0.1956 0.0394 GLDA 20wt% HEDTA 20wt% MGDA 20wt% Acetic acid Citric 10wt% acid Formic 10wt% acid 10wt% HCl 15wt% L-80 carbon steel 300 F N 2 head space 6 hour metal loss at temperature
Stimulation in carbonate reservoirs Acids are used to create wormholes to connect the formation to the wellbore Success depends on how deep this acid will penetrate into the formation creating uniform wormholes
Lab Study 1.0 ml/min Coreflood @ T and P Introduction StimWell References Conclusions
Stimulation in sandstone formations Acids are used to dissolve the soluble materials Solubility tests in the lab (samples from TU Delft - W-1) 100 C for 6 hours Solvent Dissolved [%] SW HTF 50% 9.87 SW DDH 50% 7.55 HCl 15% 14.34
Stimulation in sandstone formations Coreflood tests with Bandera cores Bandera core (10% illite)
Case Histories - Overview F Stimulation 400 350 300 250 200 150 100 50 0 400 300 250 200 150 Sandstone Dolomite Chalk Calcite Formation Descaling Pickling Applications Carbon steel ESP Cr Ni-Cr Temperature Geometry Materials
De-scaling Descaling using StimWell HTF Introduction StimWell References Conclusions
Field application I: Tight, sour gas well Production Rate (MMSCFD) 5.25 4.2 3.15 2.1 2.1 +110% 3.4 4.4 5 325 F 20% H 2 S 9% CO 2 Carbonate (calcite and dolomite) Porosity: 11.5% Permeability: 4 md CRA and carbon steel 20wt% GLDA at ph=3.4 1.05 0 Pre-treatment Post treatment target GLDA treatment Expected fracturing result SPE 163332
Field application I: Tight, sour gas well Concentration (ppm) 10000 8000 6000 4000 2000 0 0 5 10 15 20 Sample nr Effective dissolution of calcite and dolomite No after treatment required Ca Mg All flowback samples ph>6 Concentration (ppm) 50 40 30 20 10 0 0 5 10 15 20 Sample nr No corrosion 325 F 20% H 2 S 9% CO 2 Calcite and dolomite Porosity: 11.5% Permeability: 4 md CRA and carbon steel 20wt% GLDA at ph=3.4 Fe in stimulation fluid Mn Fe Cr SPE 163332
Field application II: Horizontal well Well 1 Well 2 Before stimulation Liquid rate (bbl/day) PI (bbl/day/psi) After stimulation Liquid rate (bbl/day) PI (bbl/day/psi) 680 0.8 1215 1.8 350 0.4 900 1.6 271 F 200 ppm H 2 S 6mol% CO 2 Permeability: 50 md L-80 tubular >4500 feet horizontal section completed within 4 hydraulic sliding sleeves 20wt% GLDA at ph=3.4 at 0.25 bbl/ ft Effective residual filtercake removal and stimulation from heel to toe due to slow reaction rate
Field application III: Descaling ESP 160 F FeCO 3 and CaCO 3 around ESP 20wt% GLDA at ph=3.4 The oil production increased from 400 to 512 STB/day and the PI improvement sustained for 6 months SPE 166335
Field application III: Descaling ESP Concentration (ppm) 2500 2000 1500 1000 Ca Fe Mn 160 F FeCO 3 and CaCO 3 around ESP 20wt% GLDA at ph=3.4 500 Zn 0 0 10 20 30 40 50 60 Sample nr Analysis of flowback samples proved dissolution of the scales, without any adverse impact on the ESP or well tubular SPE 166335
References Subject Reference Year Field applications Carbonate coreflood SPE 163332: SPE P&O (2013) 28-3, pp277-285 SPE 166335 SPE 168163: J. of Can. Pet. Tech., 54-5, pp289-297 SPE 173774 SPE 127923: SPEJ (2011), 16-3, pp559-574 SPE 133497: SPEJ (2011), 16-4, pp968-980 SPE 140149 Sandstone coreflood SPE 139815 SPE 143301 SPE 147395: SPE P&O (2015), 30-1, pp43-51 Corrosion SPE 152716 SPE 160849 HSE SPE 157467 SPE 168145 Reaction rates SPE 139816 SPE 164480 2012 2013 2014 2015 2010 2010 2011 2011 2011 2011 2012 2012 2012 2014 2011 2013 Filtercake removal SPE 155426 2012
Thank you for your attention Questions?