Multi-Zone Production in Three Tatarstan Oilfields. Atlas Badretdinov JSC Tatoilgas Mauro Petry Weatherford Maxim Popov Weatherford

Transcription

1 Multi-Zone Production in Three Tatarstan Oilfields Atlas Badretdinov JSC Tatoilgas Mauro Petry Weatherford Maxim Popov Weatherford April 2008

2 Outline Definition of the challenge Technical Solution Results Obtained Conclusions 1

3 The Search for Lower Production Costs Tatarstan oil fields have entered the late phase of their operation increase in water cut water produced to the surface has to be treated before disposal or re-injected increase in oil production costs lower profitability levels Drilling costs represent more than half of the total capital investment 2

4 Application Details Fields: Urmyshlinskoye, Kuzaikinskoye and Urustamakskoye Wells with multiple producing formations Commingled production is allowed 5 ½ casing & 2 7/8 tubing Artificial lift methods are required to produce Vertical wells Very low gas and sand content High water cuts Downhole temperatures below 60ºC 3

5 Scenarios 1. Produce from two zones Production Production System 2. Produce from top formation and inject water into the bottom Production Injection System 4

6 Technical Solution 1 Production Production System Produce the two formations through a single tubing string with two PCP s driven by the same rod string Isolate the zones with a packer to optimize utilization of each formation Use sensor to acquire data from operation parameters below the packer (wireless data transfer) 5

7 Downhole Schematics Production Production System 6

8 Design Considerations Production Production System Top PCP must handle the total production Rod string has to be designed for the total system torque (twice the breakaway friction torque) Advisable to use a longer top rotor to ease the spacing procedure Spacing between the pumps depend on formations perfs distance Pwf of lower formation must guarantee that the annulus up to the packer is filled up with fluid preferably the flowing pressure is higher than the bubble point pressure to ensure that no free gas will be present below the isolating packer 7

9 Technical Solution 2 Production Injection System Install two PC Pumps in a single tubing string: top pump produces fluid to surface from upper formation bottom pump is built with a left-hand helix o fluid suction is at the top of the stator o because of the distance between top and bottom pumps, there will be a natural separation of the fluids and the bottom pump sucks water only o water is then pumped downwards, into the lower zone Use sensor to acquire data from operation parameters below the packer (wireless data transfer) 8

10 Downhole Schematics Production Injection System 9

11 Design Considerations Production Injection System Rod string has to be designed for the total system torque (twice the breakaway friction torque) Advisable to use a longer top rotor to ease the spacing procedure Spacing between the pumps must be enough to allow for natural separation between oil and water Because the injection pump is operating at up thrust, minimizing the risk of rods buckling is important: design stiffer rods than the necessary only due to torque requirements apply rod centralizers if needed 10

12 Results Well #256 Completed in Jun-2002 with the Production Injection System Total operation time until Dec-2007: 1630 days (4.5 years) Operated continuously for 1018 days (from Dec-2004 to Oct-2007) Both pumps are model (3 m³/d and 1200m of lift) 5,0 Well # 256 4,5 4,0 3,5 3,0 Water 2,3 (50%) Water 1,5 (34%) m³/d 2,5 2,0 1,5 1,0 Oil 2,4 Oil 3,0 0,5 0,0 Before MZP After MZP 11

13 Results Well #217 Completed in Jun-2002 with the Production Injection System Total operation time until Dec-2007: ~1000 days (2.7 years) Pump model (production) and (injection) 14 Well # m³/d 8 6 Water 6,6 (66%) Water 7,1 (60%) 4 2 Oil 3,4 Oil 4,7 0 Before MZP After MZP 12

14 Results Well #520 Completed in Oct-2006 with the Production Injection System Total operation time until Dec-2007: 390 days (1.1 year) Pump model (production) and (injection) 10 Well # m³/d Water 3,8 (40%) Water 2,2 (25%) 4 3 Oil 6,7 2 Oil 4,2 1 0 Before MZP After MZP 13

15 Conclusions System Advantages Low project capital cost No foundation preparation is needed Construction of surface water pumping stations is reduced when the production-injection technology is applied Reduce the need to build injection wells for water disposal and/or pressure maintenance water injection projects Operating two pumps with single surface drive, tubing and rod strings Lower maintenance costs Reduced scope of commissioning activities Applicable physical limitations are the same as other PCP applications Casing and tubing minimum size No specific limitations to well deviation 14

16 Conclusions System Limitations Not every well is suitable for using the system Minimum distance between formations is necessary Commingling fluids from different formations must be acceptable Higher incidence of rods failures than usual PCP applications High Strength rods should be applied Require specific installation expertise It is not possible to set different operating speeds for upper and lower pumps Design of the system must be on the safe side (dynamic fluid levels, rod string loading, rotor/stator interference fit, etc.) Data gathering from lower pump operating conditions is difficult because of the need to transfer information through the packer 15

17 Multi-Zone Production with PCP Questions & Answers 16

18 Downhole Schematics Obsolete Design Production Injection System 17