Using Prepack Sand-Retention Tests (SRT's) to Narrow Down Liner/Screen Sizing in SAGD Wells

Abstract

Due to the unconsolidated nature of the Athabasca Oil Sands in the Western Canadian Sedimentary Basin, it is common practice to complete Steam Assisted Gravity Drainage (SAGD) well pairs with the use of standalone screens (SaS's). The sizing of the liner/screen types are commonly determined by: first, getting a particle size distribution (PSD) by dry-sieve analysis and/or Laser Particle Sand Analysis (LPSA); and second, running a number of prepack Sand-Retention Tests (SRT's).In this Nexen Long Lake study, five batches of unconsolidated McMurray Formation sand were collected from six different cored wells. Using these batches of sand, more than twenty SRT's were run with a variety of fine-tuned modifications to the traditional test protocols to best duplicate fluid production conditions as observed in the field. Some of these modifications included: altering the injected fluid/gas rate and reconfiguring the order in which the fluids / gas were injected.The SRT results were then plotted to identify if they passed the general criteria for a successful sand control device design. Unexpectedly, many of the SRT results did not meet the pass criteria for solids production and therefore, altered the direction in which future tests were run. However, when reviewing the solids production with the cumulative fluids / gas injected, the outcome commonly reverted to being favourable.Understanding the laboratory derived test results, and how they applied to the field, was instrumental in the lab testing process. By redefining the tests results and pass/fail criteria, based upon observed in-situ production conditions, it was possible to make both qualitative as well as quantitative analysis and therefore, more confidently decide on the optimal reservoir completion type.The study discusses an alternative approach to interpretation of conventional SRT results relative to observed field production conditions and how ultimately, this analysis influenced the choice of liner/ screen sizing selected for implementation in future Long Lake field development projects.

An Investigation into Current Sand Control Testing Practices for Steam Assisted Gravity Drainage Production Wells

“…A few sand control testing setups and procedures are introduced in the literature, attempting to simulate SAGD production wells. The testing devices in the literature can be categorized into two groups: slurry sand retention testing [8][9][10][11][12][13][14] and pre-pack sand retention testing [3,4,7,13,[15][16][17][18][19][20][21][22][23][24][25]. In the slurry testing, a low concentration slurry of sand and fluids is pumped into an empty cell towards the SCD coupon at a constant flow rate.…”

“…The in-situ bitumen reserves in Canada are located in unconsolidated oil sands. These naturally loose reservoirs require sand control devices (SCD) to simultaneously support the well, avoid excessive sand production, and let the fine particles pass through the slots and avoid plugging [2][3][4]. Different types of standalone screens (SAS) have been employed to complete the SAGD wells.…”

An Improved Set of Design Criteria for Slotted Liners in Steam Assisted Gravity Drainage Operation

“…Bennion et al [17] and Devere-Bennett [29] Conducted multi-phase small-scale SRT tests investigating the impact of phase change, slot geometry, and flow rate on the slotted liner's performance using a single-slot coupon.…”

“…The maximum slot size in this criterion is 3.5 times D50, and the minimum slot size is two times D70. Other researchers conducted prepacked SRT experiments to determine the proper slot size [17][18][19]29,30].…”

“…However, these factors were only partially incorporated in their experimental study. For example, Bennion et al [17] and Devere-Bennett [29] neglected the impact of slot density and suggested slotted liner selection protocols based on a single-slot coupon test.…”