Evaluation And Application Of Pikes Peak Cyclic Steam Injection Pressure Data
Authors: Miller Karl A. , Given M. 
Published: March 2010

Cyclic steam performance at Husky's Lloydminster area Pikes Peak steam pilot has been very good but efforts to further improve performance have continued. This study was initiated to determine the causes of observed injection pressure variations from well to well, and during the stimulation of a given well. A further goal was to develop applications for this information.

Analysis of the injection pressure data from the pre-1985 wells was limited in scope due to wide variations in injection rate and slug size; although low injection pressures were correlated to the presence of gas caps or bottom water; and a stepwise pressure drop through the first three cycles was documented.

The relatively constant first cycle injection rates and slug sizes used for the 1985 wells allowed a more thorough analysis. Four injection pressure histories were observed; sustained high pressure and three types of pressure reduction. These pressure reductions were subsequently correlated to the proximity of: bottom water, gas caps mature wells and other recently stimulated first-cycle wells. Therefore, injection pressure data can be used to supplement the reservoir description data obtained from logs and cores.

First-cycle data from the 1985 wells indicate that both overlapping the heated zones of previously stimulated neighbouring wells and pressure support from the aquifer could strongly affect first-cycle well performance. Net pay appeared to have less influence.

During the second cycles at the 1985 wells interwell communication occurred at all wells except those which were particularly isolated, decreasing the validity of SOR-based individual well performance evaluations. The injection pressures increased with time at the isolated wells, establishing a fifth injection pressure history.

The injection pressure history types of fourteen 1987 wells have been determined, and first cycle performance predictions were made using the 1985 well data.

Introduction

Husky's Pikes Peak steam pilot has given very good over-all performance(1, 2), but efforts to optimize pilot performance have continued. Early in the pilot's history it was assumed that steam injection pressures during a given cycle were fairly constant from well to well, and throughout the cycle at each well. Upon closer inspection significant steam injection pressure variations were observed for both initial cycle pressure and cycle pressure history, and a study was initiated to determine the causes, A similar study conducted to develop a method for detecting casing failures at Cold Lake wells was recently published, but no other in-depth discussions of this topic were found in the literature.

Due to poorer economics associated with current lower oil prices, this study emphasized analysis of routinely collected injection well casing pressure data rather than acquisition of more costly data by installing downhole pressure gauges, drilling observation wells, running tracer tests, or obtaining 3-D seismic data.

Before 1985, a variety of operating conditions were used to prove the economic viability of the pilot site, and to optimize operational procedures. Hence, the conclusions drawn from the nalysis of the injection pressure data for this period have been confined to general observations about the lower pressures observed at wells with gas caps or bottom water, or at post first cycle wells.