| Popis: |
Evaluation of fracturing treatments in tight-gas sands is often frustrated by uniqueness problems when matching gas rates and bottomhole flowing pressure (BHFP) data alone. A fit-for-purpose simulator was used to match gas rates, BHFP, cumulative water, and composition of the water during cleanup after a fracturing treatment.The simulator models physics of flow and chemical physics to provide improved history matching of the cleanup process. The well was cycled through several production and shut-in periods. Pressure transient analysis(PTA)was used along with a recently published line-of-solutions concept for evaluating the evolution of properties of the reservoir/fracture system. History matching of the well-returns data with the fracture-cleanup model provided multiple solutions when matching gas, water, and BHFP. These solutions all fell on a "line-of-solutions" using a special plot of reservoir properties as a function of conductive length. In addition, a new line-of-solutions was discovered relating fracture conductivity as a function of conductive length. PTA of several buildups provided lines-of-solutions that evolved during the course of the cleanup. These tools demonstrated that the conductive length was roughly 100 ft, but apparently cleaned up to at least twice that over the next several weeks. The fracture conductivity was much lower than expected and was the cause of the disappointing productivity. This work demonstrates that matching well-return compositionswith a fracture-cleanup model capable of chemical physics can lead to improved interpretations of both reservoir properties and fracture structure. The two lines-of-solutions provide a potentially powerful method of understanding the reservoir/fracture system |
