Dynamic Underbalance Perforating

Transcription

1 Dynamic Underbalance Perforating Subset of underbalance perforating. Uses volume of gun and sometimes added surge chambers to create downhole flow surge without flow to surface. Last for a few seconds, often enough to clean perfs Advantages: Better in long zones (?). Useful in high mud weight environments Can do limited underbalance on wireline

2 BHP (slow gauges) with UB Perforating - Data from 1983 Reservoir pressure 2500 psi UB note recovery in hours SPE King Data from Stracke showed few gallons of flow cleaned perfs)

3 Pressure Response in the Wellbore The immediate response after firing is a pressure spike followed by a rapid underbalance to a pressure lower than the actual static underbalance. This is dynamic underbalance a function of gunrefill

4 Perforating Cleanup Data from Troika field. 80 Flow rates in 3,5,4 > 25,000 BOPD Flow rates in 1 &2 in 12,000 BOPD range. 60 Underbalance, psi 40 PI (bopd/psi) TA-3 TA-1 TA-2 TA-5 TA-4 Surge/bbl? No No No Yes/40 Yes/40 Flowback 30 bbl No No 20 bbl 20 bbl Choke? Open Closed Closed Open Open

5 PulsFrac Software Output/Design on Shah Deniz Well Pressure rises quickly and then falls below hydrostatic creating flow.

6 Dynamic underbalance has always been a part of underbalance perforating. But, with high speed gauges and build ups, we are now finding how to use it more effectively. Avg. Mech. Skin Mech. Skin vs Underbalance Wells Shot w/ Open Choke 66 PBU's Underbalance Poly. (Underbalance) Overbalanced psi psi > 1300 psi PURE JOBS Data from Unocal - Thailand

7 Dynamic Underbalance Perforating Requirements 1. Sized evacuated chambers (or empty guns), near the guns, to accept enough flow after perforating to establish cleaning. 2. Quick opening valves on the chambers. 3. Knowledge of how to design for thicker intervals. 4. Liquid (low viscosity) surrounding the guns. 5. Restriction in wellbore above guns to slow upper wellbore fluid flow 6. Formation permeability sufficient to allow cleaning a. Max perm vs. average perm b. Formation fluid that will flow 1. Non damaging fluid (tested to formation and fluid). 2. Minimum skin damage in removing guns if not dropped.

8 In very long zones and in zones where the perforated intervals are scattered out, dynamic underbalance perforating has a better chance to clean each perf than regular UB. 0 V/V 1 0 % 10 1 V/V 0 0 V/V 1 1 V/V 0 METRES PERF_GUN.COMPONENT LITHOLOGY.LITHCODE V/V 1 0 % 10 1 V/V 0 0 V/V 1 1 V/V 0 METRES PERF_GUN.COMPONENT LITHOLOGY.LITHCODE V/V 1 0 % 10 1 V/V 0 0 V/V 1 1 V/V 0 METRES PERF_GUN.COMPONENT LITHOLOGY.LITHCODE V/V 1 0 % 10 1 V/V 0 0 V/V 1 1 V/V 0 METRES PERF_GUN.COMPONENT LITHOLOGY.LITHCODE SDA-01 SDA-02 SDA-03Z SDA-04 INTERP_ARRAY.VSH_PERF_5 GAS.TOTGAS_1 INTERP_ARRAY.BVW_6 SANDING_CBHFP.CBHFP_SHMAX_4 INTERP_ARRAY_BESTPERF.PAY_2 INTERP_ARRAY_BEST.PAY_2 CORE_BEST.PHI_H_1 INTERP_ARRAY.VSH_PERF_7 GAS.TOTGAS_1 INTERP_ARRAY.BVW_2 SANDING_CBHFP.CBHFP_SHMAX_4 INTERP_ARRAY_BESTPERF.PAY_6 INTERP_ARRAY_BEST.PAY_3 CORE_BEST.PHI_H_1 INTERP_ARRAY.VSH_PERF_5 GAS.TOTGAS_1 INTERP_ARRAY.BVW_3 SANDING_CBHFP.CBHFP_SHMAX_2 INTERP_ARRAY_BESTPERF.PAY_3 INTERP_ARRAY_BEST.PAY_2 core_best.phi_h INTERP_ARRAY.VSH_PERF_3 GAS.TOTGAS_1 INTERP_ARRAY.BVW_1 sanding_cbhfp.cbhfp_shmax INTERP_ARRAY_BESTPERF.PAY_3 INTERP_ARRAY_BEST.PAY_1 core_best.phi_h INTERP_ARRAY.VSH_6 INTERP_ARRAY.PHIT_6 DEPTH NKG 20 FasilaD(SP4) 42 FasilaC 57 FasilaB(SP3) 103 FasilaA 17 SP2-SP3shale 41 BX(SP2) 81 TOPS_LITH.TOPS INTERP_ARRAY.PHIT_6 INTERP_ARRAY.BVW_BEST_6 INTERP_ARRAY.VSH_2 INTERP_ARRAY.PHIT_2 DEPTH NKG 20 FasilaD(SP4) 38 FasilaC 54 FasilaB(SP3) 101 FasilaA 16 SP2-SP3shale 40 BX(SP2) 75 TOPS_LITH.TOPS INTERP_ARRAY.PHIT_2 INTERP_ARRAY.BVW_BEST_2 INTERP_ARRAY.VSH_3 INTERP_ARRAY.PHIT_3 DEPTH NKG 19 FasilaD(SP4) 41 FasilaC 4 FasilaB(SP3) 108 FasilaA 18 SP2-SP3shale 30 BX(SP2) 76 TOPS_LITH.TOPS INTERP_ARRAY.PHIT_3 INTERP_ARRAY.BVW_BEST_3 INTERP_ARRAY.VSH_1 INTERP_ARRAY.PHIT_1 DEPTH NKG 20 FasilaD(SP4) 38 FasilaC 58 FasilaB(SP3) 101 SP2-SP3shale 25 BX(SP2) 85 TOPS_LITH.TOPS INTERP_ARRAY.PHIT_1 INTERP_ARRAY.BVW_BEST_

9 DEPTH PERF COMPONENT_7 LENGTH_ Ratchet Vent_Live Surge Tandem Vent_Live Surge Ratchet VENT_LIVE Surge Gun Tandem Vent_Live Surge Ratchet Vent_Live Gun Tandem Vent_No Gun Ratchet Vent_No Gun Tandem 0.385

10 SDA04 With small number of surge chambers

11 Large Casing Small Gun 8-5/8 csg and 2-7/8 gun Large Casing Large Gun 8-5/8 csg and 5-1/8 gun

12 Large Casing Small Gun 8-5/8 csg and 2-7/8 gun Large Casing Small Gun 8-5/8 csg and 2-7/8 gun with restriction in csg

13 Holstein A-5 Perforating Run Base Case Early Time

14 Tangguh Base Case

15 Tangguh with surge chambers, but still with low viscosity brine in hole

16 Actual Data Recorder at bottom of assembly 5000 Model Results perforating fractures top interval (using provided permeability) Model Results no fractured perforations (using provided permeability) Data from a North Sea field from Marathon. Note that the modeled data closely tracks the actual data, although the PulsFrac reported permeability appears to be higher than what is reported for the zone

17 Dynamic Underbalance Conclusions Comparable to underbalance perforating in good permeability range (perhaps 10 to 100 md +???) Wellbore geometry (size and length of upper restrictions, tubing, etc.) is critical to underbalance achieved and flow duration. Restrictions above/below individual guns may be a method of obtaining higher underbalance and longer flow duration in specific perforation locations. Higher perms reportedly shorten the underbalance duration. High deviation wells may be a problem (?). Thick zones may be a challenge (?). Need to shoot and drop if possible (?).