ABSTRACT
Frequently, it is seen that production rate and flowing tubing pressure decline rapidly on abnormally pressured wells following a hydraulic fracture stimulation. It is often thought that rapid decline in production rate is due to inadequate fracture characteristics. However, the rate of decline depends on many factors, such as formation permeability, fracture half-length, fracture conductivity, reservoir pressure and reservoir size. Also on deep, low-permeability, high-pressure wells, closure stress can play an important role on the rate of decline in production when large rapid pressure drawdown is required for economic production rates.
This paper utilizes pressure transient test data and production data to evaluate a hydraulically fractured well in a geopressured reservoir. A prefracture buildup test, type-curve techniques for fractured wells with boundary effect, and a two-dimensional, single-phase simulation program with closure stress on proppant are used to arrive at an explanation for the performance of a well. It was found that a small reservoir drainage area and a loss of fracture conductivity were major factors of rapid decline in productivity.
Projections on future well performance were made and compared with subsequent actual well performance.
