The Optimal Completion Techniques for Horizontal Gas Wells in the Cadomin Formation, Northeastern British Columbia

摘要

The Cadomin formation, consisting of conglomerates and sand systems, is an aerially extensive resource play that covers the entire area of northeastern British Columbia, Canada from Township 77, Range 21W6 to Township 68, Range 11W6 in the Elmworth area. It further extends south for hundreds of kilometers along the eastern edge of the Rocky Mountains. The gross pay thickness in the Cadomin formation ranges from 20 ~ 30 meters with porosity ranging from 2 to 7% and matrix permeability ranging from 0.006 mD to 0.7mD, based upon available in-situ Special Core Analysis data. Due to the low estimated ultimate recovery (EUR) from a typical Cadomin vertical well, there have been more than 300 horizontal wells (including multi-lateral horizontal wells) drilled in this formation since 2001 in order to improve the ultimate recovery. Various completion techniques have been tried in those horizontal wells, which use mainly slick-water bullhead or multi-stages fracturing with or without proppant. After a review of the public completion data for more than 200 horizontal wells, it was found that as high as two-third of the wells had used only slick-water in either bullhead or multi-stage fracturing; about one-third used slick-water with proppant sand, and the remaining few percent using some other techniques. Detailed analysis of the completion techniques, wells' EURs and the first 3-month gas production has provided some insights into the following questions: 1. Does fracturing work better with slick-water alone or with proppant? 2. For those wells using slick-water during fracturing, does the amount of water used affecting the final EUR and initial production? Is it true that more water is used better the initial production and the EUR? 3. What are the benefits of using multi-stage fracturing vs. bullhead fracturing? 4. What is the conductivity of the fractures generated by slick-water?