Abstract
The Meramec Formation in the STACK play has moved to full field development and multiple wells are put on production in a relatively short time. Our results provide asset teams with key geologic, completions, and operations characteristics and their relative contribution to well performance. Depending on the desired economic metric (NPV or ROR), the drawdown strategy and the magnitude of intra-well interference (fracture to fracture) can be optimized. For instance, if the objective is to maximize rate of return, then tighter fracture spacing may be accepted. Results provide guidance to optimal design parameters and operational strategies in the Meramec Formation.
Optimal cluster spacing has eluded reservoir and completions engineers since the inception of multi-stage hydraulic fracturing. Very small cluster spacing could result in fracture to fracture (intra-well) interference and higher completions cost, whereas very large cluster spacing could lead to inefficient resource recovery which is detrimental to the economics of the well.
This study interrogates the relative contribution of rock matrix, completions, and operational characteristics, vis-a-vis short and long term well performance in tight oil reservoirs. Those characteristics include drawdown strategy, cluster spacing, pressure dependent permeability, critical gas saturation, and petrophysical properties. Available geologic data were integrated to construct a geologic model which will be used to history match a well from the Meramec Formation.
The static model covers an area of 640 acres that encompasses a multi-stage hydraulically fractured horizontal well. The well is unique because it is unbounded and has more than two years of continuous production without being disturbed by offset operations. History match was obtained to three-phase production and flowing bottom-hole pressure. By utilizing element of symmetry, numerical models were created to investigate the effect of fractures interference on short- and long-term oil recovery and producing gas-oil ratio.
Observations from diagnostics such as offset pressure gauges, micro-seismic, fiber optics, and radioactive tracers can provide critical insights into optimal fracture spacing. However, those observations remain incomplete without proper integration with physics-based models to predict well performance and optimize fracture spacing.
Findings suggest that drawdown strategy (aggressive versus conservative) is more impactful to short term oil productivity than fracture spacing. Drawdown strategy is even more impactful on short-term oil recovery than a 20% error in porosity, or water saturation. The profile of producing gas-oil ratio depends on fracture spacing and has been interpreted in the context of linear flow theory.
