SIR 1 Attachment DAE 2 - Alberta...The Use of Pressure Transient Analysis Tools to Interpret Mini-Frac Data in Alberta Oilsands Caprocks. Tight zones like the Lower Clearwater shale

Attachment DAE 2

Micro Fracture Test Results from 1AA/16-01-092-08W4/0

Raw test results will be submitted under a separate cover

Minifrac Interpretation SUNCOR LEWIS 16-1-92-8

July 2018

SUNCOR LEWIS 16-1-92-8 Mini-frac Interpretation Page 1 of 10

Overview The SUNCOR LEWIS 16-01-092-08 Well (1AA/16-01-092-08W4/0, Licence # 0486883) was tested by mini-frac stimulation to establish closure pressure for caprock integrity purposes. In the Lewis area, the McMurray Formation is overlain by the Wabiskaw A and the Lower Clearwater, which serves as the caprock for many SAGD operations within the Athabasca. One metre intervals were tested within each of the following zones:

1. Wabiskaw A silt 2. Lower Clearwater shale

The Wabiskaw A silt interval was tested by mini-frac operations for three fracture/flowback cycle and one fracture/falloff cycles starting on March 18th, 2018. The detailed analysis is contained in the “Wabiskaw A Silt Interval” section of this report. The interpreted fracture closure gradients from mini-frac analysis ranged from 21.5 kPag/m to 22.7 kPag/m compared to a calculated overburden gradient of 20.3 kPag/m.

The Clearwater shale interval was tested by mini-frac test for two fracture/flowback cycles and one fracture/falloff cycle starting on March 19th, 2018. The detailed analysis is contained in the “Lower Clearwater Interval” section of this report. The interpreted fracture closure gradients from mini-frac analysis ranged from 21.2 kPag/m to 22.5 kPag/m compared to a calculated overburden gradient of 20.2 kPag/m.


Figure 1: Well Logs, Vertical Stress and Minifrac Closure Pressure

Summary Table in Report Wabiskaw A Silt Clearwater

Test Depth mGL 127.5 122.5 Minifrac Closure Stress Mean kPag 2823 2590 Minimum kPag 2739 2517 Minifrac Closure Gradient Mean kPag/m 22.1 21.9 Minimum kPag/m 21.5 21.2 Standard Deviation kPag/m 0.5 0.6 Standard Deviation/Mean % 2% 3% Vertical Stress Stress kPag 2582 2390 Gradient kPag/m 20.3 20.2 Fracture Orientation Hz Hz

Table 1: Analysis Summary

In a minifrac test, the in situ failure conditions are created and the pressure required to propagate fractures can be measured. The pressure where fractures start to close is the basis for safe SAGD operating pressure since this is the minimum pressure required to open a pre-existing fracture. This represents the case where there are existing natural fractures or that the higher formation breakdown


pressure has been exceeded. A safety factor, typically 0.8, is also applied in the determination of safe operating pressure.

The method used to interpret the minifrac data are based on flow regime recognition described in SPE Paper 157843 titled The Use of Pressure Transient Analysis Tools to Interpret Mini-Frac Data in Alberta Oilsands Caprocks.

Tight zones like the Lower Clearwater shale and Wabiskaw A shale show signature Bourdet and Mattar derivative responses to closure on the Log-Log plot. The Bourdet derivative has a 3/2 slope and the Mattar derivative is horizontal (zero slope). The derivative responses are consistent for no-flow and flowback falloffs. All of the Clearwater and Wabiskaw minifracs responded in this manner.


Wabiskaw A Silt Interval The Wabiskaw A silt interval was tested by mini-frac operations for three fracture/flowback cycle and one fracture/falloff cycles starting on March 18th, 2018. The test was analyzed in the field in real-time to help direct field operations, final interpretation occurred after field operations were complete. The interpreted fracture closure gradients ranged from 21.5 kPag/m to 22.7 kPag/m. This document uses start of closure as the appropriate measure for determining fracture gradient. Results are consistent with a horizontal fracture based on the depth and density of the formation. The perforation interval was 131 -132 mKB, the downhole gauge landing depth was 131.5 mKB and the difference between ground level and Kelly bushing is 4.0m.

Pressures were recorded at the pump outlet, the wellhead and downhole, all at 1 second intervals. The data was loaded into Ecrin in absolute (kPag) units, the fracture gradients and pressure quoted in this document are also in kPag. The depth from ground level to MPP was used to calculate the fracture gradient.

Figure 2: Wabiskaw A Shale Interval Tests

The following naming convention was used to denote test information:

1. Type of test: falloff (FO) or flowback (FB) 2. Type of pick: start of closure (SOC)


Cycle # Type of Test Injection Rate Injection Duration SOC Closure Gradient Comments

FO/FB L/min mins kPag kPag/m

1 FB 50 4.0 2739 21.5 Good quality data



4 FO 100 3.2 2897 22.7 Good quality data

Table 2: Wabiskaw Shale Interval Minifrac Interpretation

The diagnostic plots of all four cycles show the 3/2 slope Bourdet derivative fracture closure. The closure picks are based on the flow regime recognition and are described in SPE Paper 157843. Closure gradient is higher than the calculated overburden gradient for all cycles. An overburden stress gradient was calculated from the 16-01-092-08 bulk density log, resulting in a vertical stress gradient of 20.3 kPag/m. The average Wabiskaw minifrac gradient was 22.1 kPag/m (lowest calculated gradient 21.5 kPag/m). The geomechanical picks are made directly from the diagnostic plots and are independent of the formation characteristics.


Lower Clearwater Interval The Clearwater shale interval was tested by mini-frac test for two fracture/flowback cycles and one fracture/falloff cycle starting on March 19th, 2018. The test was analyzed in the field in real-time to help direct field operations, final interpretation occurred after field operations were complete. The interpreted fracture closure gradients ranged from 21.2 kPag/m to 22.5 kPag/m. This document uses start of closure as the appropriate measure for determining fracture gradient. Results are consistent with a horizontal fracture based on the depth and density of the formation. The perforation interval was 122 -123 mKB, the downhole gauge landing depth was 122.5 mKB and the difference between ground level and Kelly bushing is 4.0m.

Pressures were recorded at the pump outlet, the wellhead and downhole, all at 1 second intervals. The data was loaded into Ecrin in absolute (kPag), the fracture gradients and pressure quoted in this document are also in kPag. The depth from ground level to MPP was used to calculate the fracture gradient.

Figure 3: Clearwater Interval Tests


The following naming convention was used to denote test information:

1. Type of test: falloff (FO) or flowback (FB) 2. Type of pick: start of closure (SOC)

Cycle # Type of Test Injection Rate Injection Duration SOC Closure Gradient Comments

FO/FB L/min mins kPag kPag/m



3 FO 90 3.1 2667 22.5 Good quality data

Table 3: Clearwater Interval Minifrac Interpretation

The diagnostic plots of all three cycles show the 3/2 slope Bourdet derivative fracture closure. The closure picks are based on the flow regime recognition and are described in SPE Paper 157843. Closure gradient is higher than the calculated overburden gradient for all cycles. An overburden stress gradient was calculated from the 16-01-092-08 bulk density log, resulting in a vertical stress gradient of 20.2 kPag/m. The average Clearwater minifrac gradient was 21.9 kPag/m (lowest calculated gradient 21.2 kPag/m). The geomechanical picks are made directly from the diagnostic plots and are independent of the formation characteristics.


Reference Note: This report was adapted from the Suncor internal minifrac report on well F1/06-27-095-08W4/00 by Eric Sefton.

Powless, K. R. The Use of Pressure Transient Analysis Tools To Interpret Mini-Frac Data in Alberta Oilsands Caprocks. Society of Petroleum Engineers. 2012

Documents

SIR 1 Attachment DAE 2 - Alberta...The Use of Pressure Transient Analysis Tools to Interpret Mini-Frac Data in Alberta Oilsands Caprocks. Tight zones like the Lower Clearwater shale