IPTC MS Chemical Consolidation of Sand Propped Fractures in a Chalk Reservoir Offshore Denmark With Enzymatic Calcium Carbonate Scale

Transcription

1 IPTC MS Chemical Consolidation of Sand Propped Fractures in a Chalk Reservoir Offshore Denmark With Enzymatic Calcium Carbonate Scale Marie L Morkved, Craig Knight, Bansal Bhagwan, Alejandro Garcia Algora & Wenjing Zhuang, Maersk Oil Hans Christian Rohde & Alexander C Nelson, M-I SWACO a Schlumberger Company

2 Slide 2 Safety Moment The facility was not designed for proppant/sand production

3 Slide 3 Danish Sector - North Sea Chalk Low permeability (1-10 md) Long horizontals Stimulation Fracture (acid or proppant) Matrix acidize Wells from 1980 s: Propped Fractures destabilize

4 Slide 4 Problem well SSSV Good oil producer Completed 1993 SPM 4 SPM 3 WELL SCHEMATIC 8 Propped fractures Total 6 millions pounds Choked back sand SPM 2 SPM 1 SPM 0 PGM1 No flow from below zone 5 production Zone 8 Zone 7 Zone 6 Zone 5 Zone 4 Zone 3 Zone 2 Zone 1 CT intervention July 2012 Legend Production Packer Zonal isolation Packer Sliding side door (SSD) ISO Packer Zone 8 Eroded holes in tubing Hole 75.6% of Qo (52.6% of Qt) Hole 20% of Qo (28% of Qt) 90% of oil through holes

5 Slide 5 How to stop sand (and not the oil)? Options considered: x Insert screens x Resins Enzymatic calcium carbonate Benefits: Environmentally friendly Completely reversible Life Cycle Solution 250 ft Reference Paper: SPE# Once the solution was selected lab testing was done in parallel with planning of job

6 Slide 6 Enzymatic Calcium Carbonate Scale The Reaction Urea Water Ammonia Bicarbonate 1) NH 2 CO NH + 2 2H 2 O 2NH + 4 (aq) + CO 2 3 (aq) ENZYME Calcium Solution Bicarbonate Calcium Carbonate 2) Ca 2+ (aq) + CO 2 3 (aq) CaCO 3 (s)

7 Slide 7 Laboratory Testing - Injection Unconsolidated Proppant Treatment Permeability Assessment Coreflood Pre-Treatment permeability (md) Post-Treatment permeability (md) After Injection 1 After Injection 2 After Injection 3 #1 (3 injections) #2 (2 injections) (75%) 9315 (84%) 7412 (65%) 7491 (68%) 6182 (55%) N/A

8 Slide 8 Laboratory Testing Flow Back Post-treatment sand production testing verified improved strength Failure Initiation: 2 Treatments Failure Initiation: 3 Treatments

9 Slide 9 Job Preparation Chemical Contamination Chemical Decomposition Downhole Temperature CaCO 3 Precipitation inside the CT Logistically Challenging CT on Paper

10 Slide 10 Case Study Offshore Field Application Job Execution Zone 6 Zone 5 Zonal Isolation LINER SSD Z6 SSD Z5 TREATMENT PACKERS treatment packers Downhole memory CT 221 ft 129 ft HOLE gauges to monitor & TUBING Perforations ISO Packer optimize job Formation Cooling

11 Slide 11 Case Study Offshore Field Application Job Execution Pumping of treatment Wait for consolidation Repeat 3 times Recover Packers

12 Slide 12 Case Study Offshore Field Application Well Clean Up Solids Sampling & Removal Accoustic Sand Detection Monitor Production Rates

13 Slide 13 Case Study Offshore Field Application Results 700 BOPD sand free production at a gross rate 4200 BLPD 7 Months after intervention well producing 800 BOPD Payback achieved under 100 days Limited productivity impact Productivity Index Zone 5 Zone MPL MPL Injectivity Index Zone 5 Zone 7 Inj Inj Inj

14 Slide 14 Conclusions Environmentally friendly solution for remedial downhole sand consolidation. Restored over 700 BOPD of sand free production Attention to detail is imperative and can impact the effectiveness of the chemical treatment. Above expectation performance ~151,000 STB in first 7 months

15 Questions Slide 15