Day 3: Operational aspects Opera&onal considera&ons for a s&mula&on treatment Cement quality Pressure limita&ons S&mula&on opera&ons with coiled tubing Pumprates and fracturing Perfora&ons Corrosion concerns Planning and scheduling Matrix Acidizing Volume Guidelines Fluid Selection Formation temperature Permeability 250 oF 50 gal/ft 50 gal/ft 150gal/ft 100 gal/ft 100 gal/ft 200gal/ft 150gal/ft 100 gal/ft K < 20 mD* 100 gal/ft K = 20 - 100 mD K >100 mD * Consider fracturing for low permeabilities! Paccaloni's on‐site design method ! Monitoring acid s&mula&on treatment ! Early 80's by McLoad ! Theore&cal approach introduced by Paccaloni ! Paccaloni: Maximum Δp, Maximum Rate Procedure ! The acid injected at the maximum rate and hence, maximum pwf without fracturing the forma&on ! Treatment monitored in real &me ! rb is the radius of acid injec&on ! Paccaloni suggests a value of 4 δ Paccaloni design chart for monitoring acidizing Data Required for Field Applica?on ! Reservoir and fluid properties are required to calculate the slope m ! ! ! ! ! ! ! ! reservoir pressure formation volume factor Porosity total compressibility viscosity of reservoir fluid formation thickness permeability initial skin factor ! Flow rate and pressure recorded during the treatment to calculate S ! Software installed by Service companies Paccaloni’s Diagnosis Method ‐ refined Paccaloni overes&mates the skin effect ignoring transient flow effects ! Transient flow: ! or ! So: ! The method only applies to the treatments with constant injec&on rate Diagnosis Method ‐ refined ! Superposition Time Function for variable Injection Rates Fluid at Perfs Water Water Water Time, t (hr) 0.15 0.30 0.45 qi (bpm) pwf (psi) ∆tsup b s 2 4500 4480 4400 ‐0.824 ‐0.532 ‐0.347 0.799 0.786 0.754 38 37 36 Aromatic solvent 0.60 4390 ‐0.222 0.748 35 Aromatic solvent 0.75 2.5 4350 ‐0.265 0.589 27 Aromatic solvent 0.90 2.4 4270 ‐0.113 0.587 27 Aromatic solvent 15% HCl 15% HCl 1.05 1.20 1.35 2.7 2.5 3.2 4250 4200 3970 ‐0.121 0.036 ‐0.111 0.517 0.541 0.376 23 24 15 3% HF / 12% HCl 1.50 3.7 3800 ‐0.117 0.293 11 3% HF / 12% HCl 1.65 4.1 3750 ‐0.092 0.256 3% HF / 12% HCl 1.80 4.4 3670 ‐0.051 0.225 3% HF / 12% HCl 2.10 3.9 3400 ‐0.041 0.206 3% HF / 12% HCl 2.25 5.6 3730 ‐0.186 0.187 3% HF / 12% HCl 2.40 5.6 3750 0.207 0.182 3% HF / 12% HCl 2.55 5.6 3650 0.292 0.167 3% HF / 12% HCl 2.70 5.7 3600 0.348 0.157 3% HF / 12% HCl 2.85 5.8 3400 0.404 0.129 Diagnosis Method ‐ refined 40 35 Skinfactor 30 25 20 15 10 5 0 0 0.5 1 1.5 2 Pumping time (hrs) 2.5 3 Diagnosis Method ‐ refined ! Horizontal Wells ! Difficult for real‐&me applica&on ! Monitoring Treatments in Gas Wells ! same approach for gas wells as for oil wells ! Skin Factor by Viscous Effects and Diversion ! Hawkin's formula Prac&cal applica&on 10 skin 0 20 40 60 time (min) 80 100 120 Evalua?ng Diversion 50 4 45 40 skin factor 35 30 25 20 1: NH4Cl spacer 2: HCl 3: HF/HCl mud acid 4: HEC w/sand diverter 15 10 20 30 40 50 60 70 time (min) 80 90 100 110 120 Gas wells ̶ s, apparent ̶ s, damage ̶ s, viscous Horizontal wells 6000 14 Surface Pressure Boκom Pressure Rate 12 5000 10 4000 12:28 12:57 13:26 13:55 14:24 14:52 15:21 15:50 16:19 3000 2000 20 40 60 Time (min) 6 80 100 80 4 70 time 1000 2 60 0 0 20 40 60 50 Skin -1 0 8 40 30 20 10 0 0 80 Time (min) 100 120 140 160 Rate 12:00 Pressure skin factor 120 140 160 Treatment Evalua&on & Job Execu&on ! Pre‐ and post‐job evalua&on ! Opera&onal constraints, scheduling, logis&cs, site prep, etc. Treatment Evaluation & Job Execution Treatment Evalua&on ! Pre‐job evalua&on ‐ ! Fluid Placement Simulator ! Real‐&me / post‐job downhole skin predic&on / data matching simula&on ! Evaluate in real‐&me where the fluid is going and how well it is removing damage Treatment Evaluation & Job Execution Treatment Evalua&on ! Post‐job evalua&on ! Did pump pressure match expecta&ons? ! Post‐job well test indicate reduc&on in skin? ! Produc&on compare well to predicted results? ... days - weeks day day day - days - weeks 0.5 days day - days - days - weeks - days 0.5 days day 0.5 days week day day - days day - days day - weeks day week - months Health, Safety & Environment ... Establish ‐ prior to the treatment ‐ handling and disposal procedures Resump&on of produc&on HSE aspects of s&mula&on General HSE guidelines for s&mula&on Summary ! Matrix s&mula&on treatments are aimed at overcoming ... toilets, muster point, etc Site prepara&on‐offshore Job execu&on Quality control Job Execu&on Planning Guidelines for Matrix Treatments Time required for Data gathering (incl lab tests)