Improving the Shale Gas Production Data Analysis Using the Quarterly Decline Rate:Comparison Study

Production data analysis is the main core for the petroleum industry. It is used in calculating the recoverable reserve by using DCA methods. Accurate calculation of the reserve is one of the most important criteria in order to know the future of any petroleum company. Shale gas has become an increasingly important source of natural gas in the last two decades. Due to its behavior with the ultra-low matrix permeability, horizontal wells with transverse hydraulic fracture are necessary in order to produce from the shale reservoirs. These reservoirs stimulation produce long-term transient flow regime that may last for long time until the flow reaches the boundary. Different methods were introduced in order to simulate the shale gas production performance. However, none of them was able to give an accurate way to know the transition time at which the flow reaches the boundary; they give unrealistic value for both daily and monthly decline rate. In this paper, a quarterly decline rate was introduced in order to differentiate the time at which the flow behavior changes from transient to boundary dominated flow (BDF). The quarterly decline rate is used to smoothen the operating condition of any field. It is equal to 20 %, where a transient flow exists above this value and a BDF exists below this value. Production data from four different wells in four different field with different reservoirs were used. The results show that using the quarterly decline rate instead of daily and monthly decline gives an easier and accurate way to estimate the transition time to BDF.