Constant Pressure Retorting of Oil Shale Earl D. Mattson, Carl D. - PowerPoint PPT Presentation

Constant Pressure Retorting of Oil Shale Earl D. Mattson, Carl D. Palmer Idaho National Laboratory www.inl.gov 30 th Oil Shale Symposium In Situ Processing October 19, 2010

Objective : Conduct laboratory constant back pressure oil shale retorting experiments to evaluate the effects of process variables (gas pressure and temperature) on produced fluids. Approach: Retort 150 g crushed oil shale samples in a high pressure/temperature vessel under isothermal and constant pressure conditions. Compare quantity and quality of produced oil, gas, and spent shale.

Major In Situ Controls Retort Gas/Liquid Pressure Energy Input + Time (Temperature Distribution) Product Heat Heat

Constant Pressure Laboratory Set-up References Bae, 69 Noble et al. 81, 82 Burnham et al. 82 Yang and Sohn, 85 shale Max Temp 600°C, Max Pressure 600 psi

TGA Results – Raw vs Retorted Shale ~2% wt loss Retorted • 10°C per min • Nitrogen purge • Ambient to 575°C • < 1 mm particle size Raw ~15% wt loss Decomposition Temperature Ranges Kerogen Bitumen Dolomite/Calcite

Temperature Effects t = exp(13901*(1/(T+273))-16.61)

Results as Function of Temperature Pressure = 200 psi Time = 144, 24, 4 hrs Higher Temperature • More oil generated • More gas generated • More mass removed

Oil Quality Increasing Temperature

TGA Results – Effect of Temperature Lower retorting temperature => less mass removal

Variable Back Pressure Tests • Crushed oil shale Pressure Control • Isothermal (500°C) • 4 hr testing • Variable Back Pressure – 25 to 540 psi

Results as Function of Back Pressure Temp = 500°C Time = 24 hrs @ Higher Back Pressure • Less oil generated • Approximately same gas • More mass removed

Transport vs Decomposition Kinetics Gas Sorption Sequential Sampling Results Retort Pressure 540 psi Four samples after finished Lighter gases tend to adsorb to spent shale Methane ~3X increase Ethane ~2X increase

Oil Quality Increasing Pressure

TGA Results – Effect of Pressure greater gas back pressure => change in distribution

Water Invasion • Fisher Assay type test • Ramp and Soak (500°C) • ~2 hr testing • Back Pressure 25 psi • With and with/out water addition

Fischer Assay Reported FA INL “ FA ” • Container type • Alum. • SS • Container size (L) • 1 / 3 • 1 • Sample mass (g) • 95 (+/-10) • 218.8 • Sample size (mesh) • 8 • 4-10 • Ramp rate ( o C/min) • 12 • ~7 • Backpressure (psig) • 0 • 20-30

FA Results • Red – no water • Blue – 2 ml/min

FA - Comparison w/o H2O w/ H2O

Gas Chromatograph Results – FA Comparison w/o H2O w/ H2O No difference in oil quality

TGA Results – FA Comparison

Summary Comparison of pressure controlled laboratory results • Const. Pressure – Var. Temperature (200 psi, 350-500°C) – At higher retorting temperatures – Possible issue with reaction kinetics – More oil generated – More gas generated – More mass removed – Slightly better quality • Const. Temperature – Var. Back Pressure (500°C, 25-540 psi) – At higher back pressures – Less oil generated – Approximately same gas volume – Less mass removal – Better quality

Summary (cont.) • Transport issues at high pressure – Spent shale appears to adsorb gases similar to CBM – CO 2 storage (~0.04 lbs CO 2 per ton shale per psi) • Water Intrusion Effects – Fisher Assay Results – More oil generated ?? – Same amount of gas generated – Same amount of mass removed – Distribution of kerogen and bitumen may be different (TGA) – No difference in oil quality – More H 2 and CO 2 produced with H 2 O addition • These preliminary results suggest – Operate in situ retorts at lower back pressure without water