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Pioneer Natural Resources. Monitoring the Movement of CO 2 at the Upper Spraberry Reservoir Using Well Logs. Texas A&M University. Gokul Lakshman. Outline. Pilot Information Location Pilot Design Pilot Highlights Upper Spraberry Makeup CO 2 Flood Mechanism Log Monitoring
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Pioneer Natural Resources Monitoring the Movement of CO2 at the Upper Spraberry Reservoir Using Well Logs Texas A&M University Gokul Lakshman
Outline • Pilot Information • Location • Pilot Design • Pilot Highlights • Upper Spraberry Makeup • CO2 Flood Mechanism • Log Monitoring • Objectives and Tools Used • Looking Inside CNL tool • What the logs have to say? • Decision Analysis • Production Outlook • Conclusions and Future Scope
Location O’Daniel Martin Co Canyon Reef Carriers CO2 Supply Shackelford Midland Co Glasscock Co Preston Driver Midkiff Tippett NorthPembrook Merchant Sherrod Pembrook Aldwell Upton Co Reagan Co Benedum
Pilot Design N Producers CO2 Injectors Observation wells Water Injectors
Pilot Goal • To evaluate the technical and economical feasibility of using • CO2 as a tertiary recovery agent in the low permeability, fractured sandstone of the Spraberry Trend • Pilot Objectives • Collection and Analysis of pilot performance data • To understand vertical and horizontal heterogeneities • To determine optimal usage of CO2 • Comparison of waterflood and CO2 flood performance • Work within the limitations of allocated budget
CO2 Flood Mechanism CO2 7045 1550 PSI 1U CO2 HEAVIER FRACTIONS CO2+OIL OIL 2U • Key Operating Targets • CO2 Injection Rate= 91MSCF/D • Average Reservoir Pressure= 2300PSI • Target Water Injection Rate= 250BPD 3U 4U PAY ZONES 5U 7230
Log Monitoring of CO2 flood – A Forensic science Objectives • Monitoring the movement of CO2 in the formation • Calculation of the saturation of fluids Logging Tools Used • Compensated Neutron Log • Array Induction Log
Enter Tool Physics CNL TOOL SS LS LSD Gamma Rays Formation SSD H+ SOURCE Thermalized neutrons
Logging Runs Conducted Total HCPV to be injected : 22HCPV(128MMCF) How much has been injected until now:76MMSCF Feb 22nd Start of CO2 Injection
What the logs have to say ? Successive Neutron porosity decrease observed-Jan to Dec Well 49 1u 2u 3u Gas entry 4u 5u
Jan-Mar Distribution 1u 25 20 15 10 5 0 0.025-0.038 1u Frequency Distributions in Well #49 100 90 1 80 70 60 Cumulative frequency Relative frequency 2 50 40 30 20 10 0 0.038-0.050 0.050-0.063 0.063-0.075 0.075-0.088 0.088-0.100 0.100-0.113 0.113-0.125 0.125-0.138 0.138-0.150 0.150-0.163 0.163-0.175 0.175-0.188 0.188-0.200 0.200-0.213 0.213-0.225 Neutron Porosity Distribution Jan rel freq Mar rel freq jan cum freq mar cum freq
Decision Analysis--Lets be practical? Oil in tank-Is it significant?? Whether a nominal PV of CO2 has been injected ? Have Log So Responses Been Stabilized Cease CO2 Injection
Conclusions • From neutron porosity logs there is indication of gas movement in all layers • More Logging runs required to get a clear picture of CO2 movement • My present status of research • Trying to calculate Sg using count rates • Awaiting more data from field • What I plan to achieve? • Calculate Sg for all layers • Compute extent of vertical displacement of CO2 using log analysis • Predict the horizontal movement of CO2 using tracers and gas • compositions at different wells