Pattern Fracturing: Design and Execution Case Study with Fracturing Completion for Reservoir Management in Ordos Shale Oil

Abstract

The use of volume-oriented completion and fracturing practice in Ordos Basin shale oil wells began in the mid-2010s, and it was effective in boosting productivity. However, recently, well performance has stopped improving and the engineering effort has increased, indicating that the oversized stimulation volume trigged certain mechanisms that negatively influenced production. To address this, we developed the pattern fracturing method, a new concept for platform-based completion and fracturing optimization, and it proved to be effective in a five-well field campaign. Most completion and fracturing optimization is based on a single strategy; although the job design may vary between stages or wells due to the change of lateral quality, the overall intensity remained the same. Pattern fracturing applies two strategies for the candidate wells in the same platform: one for energy charger (EC) wells and the other for reinforced producer (RP) wells. Different design objectives are applied in each EC and RP group of wells. As validated by numerical simulation, pattern fracturing can significantly reduce the chance of the interference between the wells and can recover the entire reserve more efficiently. During the field test, two of the five wells were assigned as EC wells and three were RP wells. Each EC well was completed with average 35000 m3 slickwater at maximum 14 m3/min pumping rate for each stage, while each RP well was completed with an average 16000 m3 gel-fluid at 6 m3/min pumping through a coiled-tubing-conveyed completion. Microseismic monitoring technology was used in 39 fracturing stages during the execution to visualize the reservoir section coverage by hydraulic fracturing, and high-frequency pressure monitoring technology was deployed in all stages to detect the offset well interference with precision. The benefits of pattern fracturing were clear: lower horsepower consumption, higher efficiency of job execution, and fewer perceived frac hits from offset wells observed during the job execution phases. During the production phase, the performance from the platform also showed a very positive result. This indicates that the pattern fracturing strategy does work well for Ordos Basin shale oil as a new production enhancement approach.