Closed Loop Conformance Control Methods

Transcription

1 Closed Loop Conformance Control Methods Mojdeh Delshad Research Professor, The University of Texas at Austin President/CEO, Ultimate EOR Services LLC Mature Fields North America 2015 Houston, Texas 1 Aug , 2015 rpsea.org

2 Motivation Excess water production is a major problem leading to early well abandonment and unrecoverable hydrocarbons in mature wells Current technology has limitations and results of these treatments have been sporadic and unpredictable A recent interest in gel treatments uses microgels to overcome some distinct drawbacks inherent in in-situ gelation systems We need a better understanding of recent microgel processes based on systematic laboratory experiments Ultimate objective is to predict water influx problems, select wells for treatment, reduce unwanted fluid production 2

3 Presentation Outline Motivation Overview of Conformance Control methods Numerical models to predict the outcome Produced water treatment for reinjection Field examples Concluding Remarks 3

4 Background o Conventional polymers are mobility control agents Primarily target bypassed oil More uniform areal and vertical displacement of oil Decrease likelihood of viscous fingering Not ideal when significant heterogeneity exists i.e. permeability contrast, thief zone, fractures o Polymer bulk gels are conformance control agents Presence of crosslinking agents that yield polymer networks More significant and long-lasting permeability reduction Gel treatments can be surface-produced or in-situ o New microgel technologies are also conformance control agents Lower concentrations of polymer and crosslinker More suited for in-depth conformance control 4 4

5 Causes of High Water Production Vertical heterogeneity Areal heterogeneity 5

6 Selective Water Shut-Off CLARIANT OIL SERVICES Background Extending life of a well as key objective Water production in oil & gas wells global problem Increasing water cut: - natural maturation of well - Water flood to increase pressure and sweep Problems created: lifting, disposal, separation, scale, corrosion Solution Bullhead downhole, enters all zones of production interval No expensive well interventions (e.g. wireline, coiled tubing) Reduces water production with minimal effect on oil production Value Added: Reduce scale, corrosion, sand Maintain water pressure support Improve sweep Reduce hydrostatic head 6

7 Selective Water Shut-Off CLARIANT OIL SERVICES Products and Application Every single water conformance treatment should be reservoir, well and problem specific Injector and Producer Wells Optimization Capability to determine the skin damage mechanism Design injection well remediation through a combination of chemical treatments to remove organic and inorganic damage Treatment to inhibit future damage deposition in the near wellbore allowing maximum injection rates at lower injection pressures 7 Clariant customized treatments to target any conduit from injector to producer well, thief intervals of natural fractures and/or high permeability streaks Consist of cross-linkable polymer system that can be bullheaded into the reservoir to selectively inhibit water whilst allowing continued hydrocarbon production Cross-linker and buffer solution allows the optimum water shut-off to be achieved across a range of reservoir permeability (10mD to 10D) and from 20 C to 130 C (265F)

8 Microgel Technologies Microgel lots size µm Broad permeability range (10-10,000 md) Commercially available under emulsion and powder forms High temperature stability (up to 165 C) High shear stability (20,000 sec-1) High chemical stability (CO 2, H 2 S, high salinity) Environmentally friendly Efficient in WSO and Sand Control applications Several products available: Colloidal dispersion gel (CDG) Preformed particle gels (PPG) Small calibrated microgels (SMG) 8 Alain Zaitoun, Poweltec, WorkShop EOR, IAPG, Neuquen, 3-5 November 2010

9 Example of successfull WSO treatment: Pelican Lake Horizontal Well 11-15A (Canada) Treatment Water Oil Water Cut Year 1 Year 2 Year 3 Year % 90 % 80 % 70 % 60 % 50 % 40 % 30 % 20 % 10 % 0 % 9 Alain Zaitoun, Poweltec, WorkShop EOR, IAPG, Neuquen, 3-5 November

10 Swelling Capacity for PPGs A M l M M s s M l M s : : Volume after swelling Volume before swelling Swelling capacity depends on Salinity Temperature Particle Size Crosslinker Concentration Before swelling After swelling 10

11 Experiments for Scaleup: Heterogeneous Models Parallel Flow Model(I) Three- Layer Cross Flow Model (III) 11 Sandwich Model ( II) Cross Flow Model

12 Mathematical Model The mathematical models for flow and transport of microgel are developed and implemented in reservoir simulator to characterize particle gel flow and blocking behavior in different porous media 12

13 Simulation Model of Sandpack Diameter and Length 2.54 cm, 50.8 cm Porosity, Permeability 0.386, md Initial oil Saturation 0.88 Irreducible Water Saturation 0.12 Pore Volume 99.4 cm 3 Temperature C Salinity 1 wt% KCl (0.134 meq/ml) Mineral Oil Viscosity 37 cp Residual Oil Saturation Duration of Experiment 268 min PPG flood Pore volumes injected 1 wt% KCl flood 2.5 PV 2000 ppm PPG in 1 wt% KCl 1.2 PV 1 wt% KCl post flush 1.7 PV Injection 13 Water Flood 1.7 PV PPG Injection 1.2 PV Water Flood 2.5 PV Production

14 Recovery (%OOIP) Water Cut Simulation of Sandpack Experiment Water Cut Water Flood PPG Injection Water Flood UTGEL 0.6 Lab Data Water Flood PPG Injection Water Flood UTGEL PV Injected Lab Data PV Injected 14 Total Oil Recovery

15 Field-Scale Simulation No. of grids Dx = Dy 32.8 ft Dz (ft) 10, 20, 10 Porosity 0.3 Salinity 3411 ppm Ratio of K v /K h 0.1 Simulation time 1000 days Fluid Properties Residual water saturation 0.25 Residual oil saturation 0.15 Oil viscosity 37 cp Water viscosity 1 cp Injection/Production data No. of wells 4 injectors and 9 producers PPG concentration 750 ppm Injection/production rate ~ 1500 bbl/day Injection design Base case: 100 d waterflood PPG: 100 d waterflood 300 d PPG injection 600 d waterflood

16 PPG Field Simulation Permeability Distribution Initial Water Saturation 16

17 PPG Field Simulation PPG concentration at 200 days Oil saturation at 200 days 17

18 PPG Field Simulation PPG RRF (end of PPG flood) RRF (end of post water flood) 18

19 Water Cut Oil Recovery (% OOIP) PPG Field Simulation 100 PPG flood vs. Waterflood Oil Recovery PPG flood (60 % Oil Recovery) % 80% PPG flood vs. Waterflood Base Case: Waterflood 20 0 Base Case: Waterflood (26 % Oil Recovery) Time (Days) 60% 40% PPG flood Water Cut 20% 0% Time (Days)

20 PPG Evaluation with Conduits A synthetic case was generated to simulate PPG s propagation through a long reservoir conduit PPG was capable of propagating through the conduit, reducing its permeability, and subsequently improving the sweep efficiency - this was observed by the change of water saturation profile through the reservoir with time Required studies and matching attempts ongoing to further validate the simulator 20

21 PPG Evaluation with Conduits PPG treatment simulated in a scenario where there is a conduit aligned in the middle of a waterflood injection pattern PPG was capable of diverting injected water to producers located off conduit s direction - this was observed by the change of water saturation profile throughout the reservoir with time Optimization attempts ongoing to further understand how to optimize PPG treatment in different waterflood scenarios 21

22 Water Treatment Solutions o o 22 Goals: Determine if CEOR chemical recovery is desired for reinjection or if CEOR chemical should be removed/destroyed Identify technologies which can treat PW to the specification required for PWRI Maximize treatment efficiency and address weight, footprint, and other unique aspects of ASP projects If downstream treatment is necessary to meet CEOR salinity/hardness requirements, PWRI treatment also dictated by downstream unit operations: Reverse osmosis (RO) desalination of nanofiltration (NF) softening Ion exchange Alternative technology (forward osmosis, electrodialysis, membrane distillation) Upstream Requirements Parameter Units RO and NF Ion Exchange Alternatives Turbidity NTU Oil mg/l <1 <1 <5-20 Temperature C SDI NA

23 Summary and Conclusions Microgels have great applications in WSO/Conformance with higher stability than conventional polymers Experiments were performed in both fracture and sandpack to rank the effect of PPG on improving conformance and reducing water cut Mathematical models were developed for rheology, adsorption, swelling ratio, resistance factor, and residual resistance factors Gel transport models were implemented in a reservoir simulator and validated against laboratory experiments Framework provides guidance for better design and optimization of microgel water shutoff process Water production can significantly be reduced Produced water reinjection should be seriously considered for conformance methods 23

24 Acknowledgement Water Management in Mature Oil Fields using Advanced Particle Gels, RPSEA Contract # Lisa Henthorne, SVP & Chief Technology Officer, Water Standard Clariant 24 rpsea.org

25 Microgels Injection Experiments Objectives o Obtain recovery factor and water cut during water injection and gel injection processes o Obtain the gel concentration effect on RF, RRFw, RRFo, and injectivity index o Determine thermal effect on microgel propagation o Study permeability effect on microgel propagations Experiment Model Five Pressure taps Heater 53