A Systematic Approach to Constrain Unconventional Reservoir Solutions with Technology Applications: A Case Study for Hydraulic Fracture Monitoring in the Jafurah Basin of Saudi Arabia

Abstract

Ultra-low permeability source rock resources require multistage hydraulic fracturing stimulation in which a combination of fluid and proppant is injected into formations at high pressure to create permeable paths for hydrocarbon flow. Fracture half-length and height are key productivity parameters for assessing the access attained by fracturing stimulation in the vertical and horizontal direction. These parameters are also critical for defining well spacing in field development. The challenge is understanding the hydraulic fracture geometry, and therefore warranting the need for its assessment. For the Tuwaiq Mountain in the Jafurah Basin, two microseismic mapping acquisitions were undertaken. To refine and validate observations from these microseismic mapping projects, the events were calibrated by fracture modeling and additional supplementary surveillance such as tracers and pressure gauges were used. The most recent fracture monitoring experiment involved three 5,000 ft horizontal wells in the Tuwaiq Mountain. All wells underwent multistage plug-n-perf hydraulic fracturing with different frack designs; mainly driven by slurry volumes and proppant concentrations. Microseismic monitoring was used to provide insights on fracture geometry, reservoir access and stage isolation, which are critical in determining optimum well spacing and stimulation design. Though microseismic fracture mapping was the primary focus of the study, other diagnostic/surveillance techniques were utilized to reduced uncertainty and validate observations. The utilization of these different and independent surveillances technologies allowed for a more comprehensive understanding of the fracture propagation behavior and fracture geometry. Chemical tracers were used as an indicator of stage contribution and also interwell hydraulic fluid communication. The pressure interference was used to provide possible fracture communication and validate the observed microseismic geometries. As a result, a clear correlation between stimulation design and fracture geometry was established. Additional uncertainties remain in understanding the fracture height and propagation of the hydraulic fracture length, as a function of the volume of stimulation slurry was doubled. In this case study, we will show how microseismic monitoring indicated effective stage isolation, upper ends of hydraulic fracture geometries, and the manner in which the targeted reservoir was accessed during stimulation operation. These results have proven valuable in aiding completion design optimization, while providing the necessary insights to progress this emerging play toward field development.

AAPG Datapages/Search and Discovery Article #90328 © 2018 AAPG Middle East Region GTW, Maximizing Asset Value: Integrating Geoscience with Reservoir Management & Facilities Optimization, Muscat, Oman, April 30 – May 1, 2018