Abstract
The Unified Fracture Design (UFD) concept provides a mechanism to determine the optimal hydraulic fracture design for a given amount of a selected proppant, while modern hydraulic fracture treatment execution offers the potential to achieve the optimal design. The proppant number is a ratio of the proppant permeability and proppant volume product to the formation permeability and reservoir volume product. The cost of the hydraulic fracture treatment is directly related to the quality and quantity of proppant injected and successful achievement of the optimal fracture treatment easily offsets this cost when appropriate economics and physical and logistical constraints are considered in the job design. Pressure transient and production data analyses are described in terms of fracture length and conductivity and do not address parameters important to the UFD evaluation. A previous paper described the use of post-treatment analysis to evaluate the effectiveness of the treatment in terms of dimensionless productivity index, dimensionless fracture conductivity, and the proppant number.
With more and more permanent gauge installations, opportunities for pressure buildup analysis may occur under normal operating conditions without a specific test design. In this case both pressure transient and production data analysis may be available. The analysis addresses both single-phase oil and gas primary production and oil production under pressure maintenance or waterflood. Also, non-ideal fractures with height growth beyond the producing formation thickness and fracture skin are considered. Field examples will include both hard rock and soft rock fracturing case studies.
The importance of this analysis is paramount for operators trying to optimize high value hydraulic fracture treatments.
