The Application of Hydraulic Fracturing Models in Conjunction with Tracer Surveys to Characterize and Optimize Fracture Treatments in the Brushy Canyon Formation, Southeastern New Mexico
Authors: Johnson Raymond L. , Woodroof Robert A. 
Published: December 2007

In this study of the Brushy Canyon Formation, sonic-derived, rock-mechanical properties and bottomhole treating pressure (BHTP) data from fracture treatments will be history-matched with a fully three-dimensional (3D), a lumped 3D, and a pseudo 3D fracture model. Height dimensions obtained from these history-matches are compared with temperature and radioactive tracer surveys to better characterize fracturing mechanics in this Delaware Mountain Group formation. Cases will be presented from Eddy and Lea Counties in southeastern New Mexico.

Introduction

The Brushy Canyon Formation, Delaware Mountain Group, in southeastern New Mexico has been a prolific oil and gas producer. The Delaware is defined as a slope-basin depositional environment consisting of several channels in submarine fans. Brushy Canyon zones exhibit good permeability (1-10 md), but often require fracture stimulation to be commercially successful. Recent work indicates that better logging techniques are possible for discerning oil saturation and potentially productive intervals within the Brushy Canyon sequence. Besides formation evaluation, another advancement in Brushy Canyon completion technology would be the ability to better model the mechanics of hydraulic fracturing in this Delaware Group member. This technology could result in more successful completions, since fracture treatments often result in uneconomical completions when high water saturation intervals are fractured or encountered during the fracturing process.

Many authors have proposed methodologies to improve hydraulic fracture placement in the Delaware Group and some have identified the lack of effective barriers through treatment evaluation. This study will evaluate, using more than one 3D fracturing model, two high-rate Brushy Canyon treatments which developed excessive fracture heights. The history-matched fracture heights will be compared with post-treatment temperature and radioactive tracer surveys. Recommendations and future treatment strategies will be presented based on the results of these history-matches.

Well Data and Treatment History Data for this study include sonic-derived, rock-mechanical property logs from both Eddy and Lea Counties, NM. The Eddy County, NM case (Case 1) includes a step-rate and flowback test (Fig. 1); a mini-frac test (Fig. 2); and a fracture treatment (Fig. 3). The Lea County, NM case (Case 2) is a fracture treatment (Fig. 4). Both fracturing treatments were pumped to completion at similar injection rates (30+ bbl/min); operators abandoned both zones due to excessive water production.

Case 1, Eddy County, NM. For the step-rate, flowback and mini-frac tests, BHTP data were obtained by means of an annular deadstring; BHTP data during the frac treatment were calculated from surface pressures. Parting and closure inflections from the step-rate test, flowback test, and mini-frac pressure fall-off correlated and compared within 20 psi to inflections observed following the fracture treatment. Conventional, single-isotope radioactive tracers were used in both the mini-frac and proppant-laden (main) frac treatments.

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