Multidisciplinary Data Gathering to Characterize Hydraulic Fracture Performance and Evaluate Well Spacing in the Bakken

Abstract

To effectively drain hydrocarbon from unconventional plays, operators have been optimizing their drilling spacing unit (DSU) well spacing for many years. This paper presents a continuous improvement of Bakken well spacing using trial pads with smaller spacing and multidisciplinary data gathering to understand the most effective spacing between wells. The operator's standard well spacing between Middle Bakken (MB) wells in the East Nesson (EN) area [Alger Field] ranges from 500 to 700 ft. To understand the optimum spacing between wells in this area, the operator trialed well spacing of 500 ft between like formations. The spacing between Middle Bakken and Three Forks wells was 250 ft. Data gathered during the spacing trial included microseismic, microseismic depletion delineation (MDD), radioactive (RA) tracers, chemical tracers, image logs, pressure measurements during completion/flowback/early-time production, and diagnostic fracture injection tests (DFITs). The data was used to calibrate advanced hydraulic fracture models and guide next-generation reservoir simulation history matching to characterize multiwell production behavior. The MDD in the parent well provided data to "map" drainage patterns, showing that drainage was limited to the MB formation. However, microseismic showed that hydraulic fracture height extended from the Three Forks second bench (TF2) up through the Three Forks first bench (TF1), Middle Bakken, and into the overlying Lodgepole (LP)—connecting the entire Bakken petroleum system. The microseismic also showed asymmetric fracture growth toward the parent well in the DSU, but the asymmetry diminished as completions progressed away from the parent well. In addition to the MB-TF connectivity indicated from the microseismic, RA tracers pumped from a TF2 well were detected in a Middle Bakken well. The implied transport of proppant from a lower TF completion to the MB increases the likelihood of production communication between formations. Chemical tracers (oil and water) pumped during hydraulic fracturing operations were found from one end of the pad to another (over 2,500 ft) regardless of formation; another confirmation of hydraulic communication between Middle Bakken and Three Forks wells. The hydraulic fracture model was calibrated using microseismic data and used for subsequent reservoir simulation history matching. The workflow consisted of modeling the parent well hydraulic fractures and history matching production, performing geomechanical modeling to determine the effects of parent well depletion on 3D stress state for hydraulic fracture modeling of the infill wells, and production history matching of the entire pad. The modeling showed significant fracture-to-fracture communication and well-to-well interference. The operator quickly used these learnings to optimize well spacing across the area to maximize DSU value.

Advancements and Operational Insights in the Bakken Shale: An Integrated Analysis of Drilling, Completion, and Artificial Lift Practices

“…Lorwongngam et al [72] modeled a pilot pad in the Bakken. To constrain their model, they used DFIT for stress and pore pressure estimation, microseismic for hydraulic fracturing geometry, MDD for drained area mapping, and RA tracer to quantify the uniformity index and the fracture propped half length of the fracture treatment.…”

Advancement in Hydraulic Fracturing for Improved Oil Recovery

“…Fiber optic was used in-well and offset wells for different purposes. The in-well fiber optic is used to evaluate the seal between two stages [23] or to quantify uniformity index between different clusters of the same stage [30,31]. Jin et al [32] utilized in-well fiber optic to quantify conductivity changes and fracture response during production.…”

“…These event are collocated at depleted zones. This approach have been applied several times to map the drainage area of parent wells in the Bakken and optimize well spacing of infill wells [43,44].…”

Using Laboratory Results from New Methods of Measuring Proppant Conductivity to Model Hydraulic Fractures in Reservoir Simulation

“…Figure 1 The improvement of hydraulic fracturing techniques focuses on determining the effective placement of proppants to provide and maintain fracture conductivity. The Bakken Formation of the Williston Basin is the primary source of production data for this research [13]. Several proppants have been used since production began in the Bakken Formation because the low permeability of the formation makes the Bakken commercially viable only with the application of hydraulic fracturing [3].…”