Integrated Study Leading to Discovery of Thin Pay Sands and Challenges Associated with Development Shaikh Abdul Azim February 10, 2014
Outline Location and Geological Setting Zubair in RA and SA Fields New Oil Find and surge of activity Integrated Study for developing thin pays Trapping in SA compared to RA Development Strategy Challenges Achievements Opportunities
Raudhatain and Sabiriyah Fields Raudhatain Iraq Kuwait Ratqa Southeast Ratqa Abdali Bahrah Medina FAILAKA ISLAND Arabian Gulf Sabiriyah Dharif Khashman Abduliyah Minagish KUBER ISLAND Greater Burgan QAROH ISLAND Saudi Arabia Umm Gudair UMM AL-MARADEM ISLAND AL-KHIRAN Wafra 3 N
Zubair Reservoir in North Kuwait GR + Raudhatain SHALE UPPER 1,400 Feet SAND SHALE Sabiriyah SAND MIDDLE SHALE SAND
Upper Zubair Sand Fluid Distribution in RA and SA
Middle Zubair Sand Fluid Distribution in RA and SA
Zubair in RA and SA Fields Raudhatain Field A major reservoir: Commercial production for 5 decades Second highest contributor to production Highest dry oil producer Sabiriyah Field Not considered to have commercial oil till 2006
South Sabiriyah: Hydrocarbon in Zubair/Ratawi Lower Zubair Sand: Condensate
Fluid Contacts Integrated Study Sequence Stratigraphy Depositional Environment Fault Seal, Pressure difference Structural History; Regional correlations Seismic Signatures for Channel Definition Sediment transport direction Oil migration Oil occurrence in Sabiriyah Zubair and Ratawi
Zubair Reservoir Reservoir Architecture and Trapping in Raudhatain 11
Sequence Stratigraphy
Depositional Model
Depositional Model
Raudhatain Correlation of Zubair in RA and SA wells Sabiriyah INTER FIELD Correlation
Correlation of Zubair/Ratawi in RA and SA wells
W E KL MU RA BH BU Regional correlation within the Zubair Formation along depositional dip.
Raudhatain Field: Reservoir Pressure declining with time
Pressure
Trapping Water Zone and Leaked oil Zone in Middle Zubair Tar in Upper Zubair Sand Tar All thick channels in UZ and MZ leaked Highly faulted SA structure High NTG: less clay smearing across fault plane Conductive fault planes
How Oil is trapped in SA-Zubair? 1. Thin Sands within Shales
How Oil is trapped in SA-Zubair? 2. Thick sand bodies in LZSD: Thicker Shales above
Role of Fault: Not unique OWC in UZSD -9368-9145
Not unique OWC in UZSD/UZSH -9368 UZSD UZSH
Compartment Compartment Depth Saturation Plots for Fluid Contacts High Sw at shallower depth show leaked compartments
Oil: Source to Trap
Oil Entrapment in Zubair
Development Strategy South Sabiriyah: Better quality oil bearing sands Targeting Channel Sand above Ratawi Shale Developing thin sands Moving towards north Ratawi Shale
Channel in Z_ls erodes Ratawi shale Difficult to predict: SA-290 lying less than 500 m misses the channel
Mapping Channel from Seismic attribute as a Guide Thickest Oil bearing Layer in Sabiriyah Zubair
Sand thins towards North Source from South Observed in 4 Wells Channel trend Established from RA field with more well Control Minimum Channel width 400m Net Sand thickness of Z_ls Channel in Z_ls
Thin Pays South North
Thin Pays South North
Net Pay of Bottom Sand (Z_ls6) PHI>=8% PHI>=12%
Prospective Areas Green: Oil Downto Blue: Transition
Developing Ratawi Shale: A stratigraphic trap Average Thickness: 8 ft Cemented Sandstones
Light oil in a thin shoreface sand Gross thickness decreases towards North Sand pinch out towards North Source from South Gross thickness of RS66 Net Sand thickness
Phases of Development
Phase-2 MRC (Horizontal Wells) for 4-8 ft sands with poorer reservoir quality Phase-1
Z_ls6 Planned to develop with Horizontal Wells PHI>=8% PHI>=12%
Z_ls6 11747 7" Shoe 11721 First deep Horizontal well
SA-A Oil Rate: 2706 BOPD W/C: 0% Choke size: 64/64 WHP: 1092 psi
Liquid Rate Oil Rate WC GOR Choke WHP 1 4045 BLPD 3074 BOPD 24% 1002 36/64 1796 psi 2 3468 BLPD 2948 BOPD 15% 917 32/64 1862 psi Days 103 Horizontal Length 2130
The targeted thin sand in the pilot hole Initial Testing Results Choke Qoil GOR WHP WC 32/64 3366 841 1810 3 24/64 1900 925 1955 3 Days 123 Horizontal Length 1709
Liquid Rate: 2140 BLPD Oil Rate: 1753 BOPD W/C: 18% Choke size: 32/64 WHP: 951 psi Horizontal Length 1097 Shale Intv(bottom) 60 Coal Interval 140 Sand Interval 897 Days: 115
Deep MRC Wells Long Rig time Challenges Thick section: Shale dominated towards bottom Shale at top of Target Geo-steering, within 4-7 ft sand, tool reliability Short landing casing Casing buckling while lowering Presence of coal at top of Target Reservoir Pressure
Short landing casing PIL Hor Z_ls6 11747 7" Shoe 11721
Days 123 Casing buckling while lowering The targeted thin sand in the pilot hole
Presence of coal at top of Target Geo-steering, within 4-7 ft sand, tool reliability Horizontal Length 1097 Shale Intv(bottom) 60 Coal Interval 140 Sand Interval 897 Days: 115
Faulted Structure
Achievements Oil production 20 million barrels Very high quality Dry oil Supporting NK Production Target Experience of developing similar sands in other Reservoirs
Opportunities Thicker Channels of Z_ls towards south and other parts of field Commercial production from South Sabiriyah extend to North Deeper OWC towards South: to spill point Porous areas for Ratawi Shale Fault compartments in UZSH,UZSD,MZSD with independent oil pools adding to STOIIP
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