SPE 121697Improvement of Drilling

Operations on Horizontal Wells at the Orinoco’s Heavy Oil Belt,

Venezuela

Nilson Muñoz (PDVSA) Luis Andérico, Ender Larreal, Martín Ruiz

(Halliburton).

Orinoco’s Heavy Oil BeltLargest deposits of extra heavy crude oil

South East Venezuela55,000 km2

8.5 degree API 1,300 centipoises at 127 °F

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Orinoco’s Heavy Oil BeltThe reservoir characteristics include:

•Unconsolidated sands (1400 to 3100 feet TVD)•28-40 % porosity•3-30 Darcy permeability•10% water formation saturation •1100-1300 psi reservoir pressure•125-130 °F reservoir temperature•30-250 foot of net pay

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Heavy Oil Drilling OperationCommon problems while drilling horizontal wells:

– High friction (drillstring and heavy oil-sand) • Excessive torque and drag• Stuck pipe incidents• Shaker screen blinding

– Environmental risk (use diesel as lubricant)

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Wellbore Schematic

Single-horizontal well

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Typical Mud Formulations

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25.0-30.0 ppbCalcium Carbonate10-20% by volumeLubricant (Diesel)

0.3-0.5 ppbPotassium Hydroxide7.0-10.5 ppbPoliglycol4.0-6.0 ppbOrganic Salt2.0-4.0 ppbPreserved Starch1.0-2.0 ppbXanthan Biopolymer

Polymer/Inhibited Fluid (Build section)0.3-0.5 ppbPotassium Hydroxide

12.5-15.0 ppbBentoniteGel/Water Native Fluid (Surface hole)

Typical Mud Formulations

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25.0-30.0 ppbCalcium Carbonate10-20% by volumeLubricant (Diesel)

0.3-0.5 ppbPotassium Hydroxide0.1-0.2 ppbBiocide2.0-4.0 ppbPreserved Starch1.0-2.0 ppbXanthan Biopolymer

Drill-in Fluid (Horizontal section)

Borehole Friction Factor Calibration

Torque measurement – 2D wells

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481.2Average

58515,00014,41510.081.824,6003,1408,421CIB-28340015,00014,60041.954,6823,0508,412CIB-282

1,12016,00014,88001.984,6852,9648,316CIB-28184716,00015,15317.461.974,3533,1258,343CIB-280-54614,60015,14622.442.034,6233,0568,681CIB-278

TorqueDifference(Estimate

– Real)

Real Torque(lb-ft)

Simulation Estimated

Torque(lb-ft)

Azimuth (degree)

Displacement / TVD Ratio

Horiz. Length

(ft)

TVD (ft)

Total Depth

(ft)

Well Name

Cluster M20I – Cerro Negro Field

Borehole Friction Factor Calibration

Torque measurement – 3D wells

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2,782Average

2,35916,00013,64156.181.933,6373,1678,415CIB-2862,01918,00015,98153.982.074,4383,0719,053CIB-2852,98319,00016,01747.582.124,4352,9768,960CIB-2843,76720,25016,48366.712.044,4962,9698,967CIB-269

TorqueDifference(Estimate

– Real)

Real Torque(lb-ft)

Simulation Estimated

Torque(lb-ft)

Azimuth (degree)

Displacement / TVD Ratio

Horiz. Length

(ft)

TVD (ft)

Total Depth

(ft)

Well Name

Cluster M20I – Cerro Negro Field

Borehole Friction Factor Calibration

Torque measurement – Well CIB 285

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Laboratory Mud Test API lubricity test

Polymer/drill-in mud (9.0 ppg)

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Laboratory Mud Test API visual wettability test

15% of hydrocarbon-free lubricant and oil-sand mixture

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Mud Field Performance Torque and drag reduction- Well CIB-297

Field test adding hydrocarbon-free lubricant

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Case HistoriesWell CIB-289 (Single-Horizontal)

3% v/v hydrocarbon-free lubricant into drill-in mud• Torque & drag decrease to 8,000 ft-lb• Cleaning and calibration trips were not required

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Case HistoriesWell CIB-295 (Multilateral)

• Torque reductions of up 17%• More lateral branches lengths• Saving 5.63 days based on the well plan

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Beneficial Drilling Practices

• Good hole cleaning conditions• Low solids concentration • Optimize transferring weight to the bit• Minimize dog leg, connection time• Maintain suitable drilling fluid properties• Alternatives for mechanical friction reduce

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Conclusions

• Reduction of torque and pipe drag of up 30%

• Allow to achieve project targets in a safe and timely manner

• Reduce environmental impact

• The heavy-oil production rate demonstrated minimal impact on return permeability

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