Conditioning the Estimating Ultimate Recovery of Shale Wells to Reservoir and Completion Parameters.

摘要

In the last years, gas production from shale has increased significantly in the United States. Therefore, many studies have been focused on shale formation in different areas such as fracturing, reservoir simulation, forecasting and so on. Forecasting production or estimating ultimate recovery (EUR) is considered to be one of the most important items in the production development planning. The certainty in EUR calculation is questionable because there are different parameters that impact production and consequently the EUR such as rock properties and well completion design.;Different methods to calculate EUR have been used in the industry. Traditionally, the decline curve analysis method by Arps (1945) was considered to be the best common tool for estimating ultimate recovery (EUR) and reserves. However, the Arps' equations over estimate of reserves when they are applied to unconventional reservoirs (extremely low permeability formation). The reason is that Arps' equations only work for Boundary Dominated Flow (BDF) decline. On the other hand, many research papers show that the production from the unconventional tight reservoirs is distinguished by an extended period of late transient flow, until reaching the boundary-dominated flow. To overcome these problems and improve the unconventional reservoir's production forecast, researchers have developed new empirical methods which are being implemented in all flow regimes.;These new and traditional methods have been applied in this research to calculate the EUR for more than 200 shale wells. The results of EUR will be subjected to study and condition with rock properties, well characteristics and completion's design parameters. The porosity, total organic carbon, net thickness and water saturation are the main rock properties that are considered in this research. Furthermore, the impact of different well design configurations (for instance, well trajectories, completion and hydraulic fracturing variable) on EUR will be inspected this study. In addition, it will be determined from this research whether reservoir or completion parameters have the most impact on EUR. This study will provide the natural gas professionals insight and clarification regarding the effects of rock properties and well design configurations on estimating the ultimate recovery for gas shale.