1. Perforation Strategy for Sand Management in
Lower Fars Unconsolidated Formation
Presented by: Amr Zeidan
Heavy Oil Group

2. Outlines Objective Approach used in the study
Conclusion of Laboratory test
Well modeling on Perforation sensitivities
Performance comparisons and ranking
Findings and analysis
Completion with and without Sand Control
Recommendations and way forward
Q&A

3. Objective
To develop a perforation strategy for Lower Fars formation in 60 MBOPD Project phase-1 based on the learning from NLSTP (North Large Scale Thermal Project)

4. Approach used in the study
Laboratory Test
Well Modeling
Actual Field Data

5. Conclusions of laboratory tests
Whole core samples taken from shallow oily sands can be effectively recovered and used for large-scale perforation and flow testing applications.
Perforation penetration depth is adequate in the subject sands, and attention should focus on the hole size in the cement and casing.
Based on laboratory results, steam stimulating SR field will result in enhanced production because of the favorable response displayed by the viscous oil when heated.
Maintaining pressure in the wellbore over 200 psi higher than the pore pressure during perforating will help mitigate plugging of the casing caused by the small DUB (Dynamic Underbalance) effect during the perforating event.
Relatively smaller holes, approximately in. in diameter, in the casing at approximately 4 SPF are feasible during the CSS cycles to ensure a uniform steam injection profile, as well as provide for a sufficient surface flow area when the well is turned over for the production phase of the cycle.

6. Prosper Model with Sensitivity to Shot Densities (SPF)
IPR (inflow performance relationship Pressure vs Liquid rate is generated by Prosper model to evaluate the performance of the inflow from the reservoir at different current perforation densities.
The higher the shoot density the higher the AOF (absolute open flow).
AOF by definition is a theoretical value indicated the maximum liquid rate when the Pwf (Bottom hole flowing pressure equal zero

7. Prosper Model with Sensitivity to perforation Entrance Hole Diameter (EHD)
The bigger the entrance hole diameter of the perforation charge, the higher the AOF (absolute open flow).

8. Different combination sensitivities
Different combination of SPF and EH then the current ones can give higher AOF (absolute open flow) for example 6 SPF and 0.38” EH

9. Perforation System Selection
Perforation selection role in production optimization
Considerations for selecting best perforation strategy
Nature of formation and level of consolidation
Type of production and/or EOR
Number of wells to be perforated
Basis of selection (Laboratory work, well modeling, and actual field data)
Well model compares production rate VS. Different EHD and SPF

10. Actual Field Data
Three types of perforation were considered to evaluate the performance of those wells
Evaluation based on their performance about sand production and normalized total production rate
A number of wells from the CSS pilot were selected with the following perforation parameters:
6 SPF, 0.24” EHD
9 SPF, 0.38” EHD
12 SPF, 0.8” EHD
Two of those wells were subjected to steam injection from the first day as they are dedicated injector in the coming phase of SF (SR-136 and SR-118)

11. Sand accumulation in wellbore
Sand production plugs artificial pump and defer production
Sand production can cover perforation intervals and cease production
How to manage sand production by selecting appropriate perforation strategy??

12. Wells’ sand and liquid rates ranking

13. Comparison results for cold production
Wells perforated with small perforations EHD 0.25” had less sand production based on the height of sand measured during well interventions but lowest production rate
Small EHD created critical drawdown which managed the sand production (in agreement laboratory work recommendations).
Wells perforated with 0.38” EHD had a medium sand accumulation but best production rate
BH 0.8” EHD had the worst sand production and moderate production rate.
Further analysis and evaluation of the study focused on comparing 0.25” and 0.38” EHD wells.
Due to mixed results of wells received steam from the beginning , further analysis carried out for hot production for fair comparison

14. Hot Production comparison based on normalized average Rate
Comparison of normalized average rate between cold and hot production

15. Completion with and without Stand Alone Screen

16. Sand control completion
Number of stand alone screens (SAS) installed in NLSTP wells to evaluate well performance under sand control completion. Evaluation is ongoing.
5 Acre:
SR-143
SR-128
10 Acre:
SR-110
SR132

17. Conclusions
The performance of 6 SPF, 0.24” EHD outperformed the 9 SPF, 0.38” EHD from sand production perspective during cold production but showed less production rate.
The performance of 9 SPF, 0.38” EHD outperformed 6 SPF, 0.25” EHD during hot production from liquid rate perspective and showed mixed results for sand production during cold production period.
Decision for perforation is based on the development strategy of the commercial project where the majority of the wells will be steamed from day one.
The conclusion is to perforate all the wells in the commercial project with 9 SPF, 0.38” EHD.

18. Q&A
Thank You