Study of Pressure Propagation in a Reservoir from a Producing Well

• Main Authors: Bieng-Zih Hsieh, 謝秉志
• Other Authors: Zsay-Shing Lin
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/95974756481049251217

博士 === 國立成功大學 === 資源工程學系碩博士班 === 95 === The purposes of this study are: (1) to estimate the propagation of the radius of investigation from a producing well in an infinite reservoir by using both analytical and numerical methods; and (2) to estimate the starting time of transient pressure affected by reservoir boundary, i.e., the boundary effect time in a bounded reservoir, and concurrently determine the radius coefficient in the linear relationship between the square of dimensionless radius of investigation and dimensionless time. In an infinite reservoir, the square of the dimensionless radius of investigation is linearly proportional to the dimensionless time. The radius coefficient in the equation is the linear proportional constant, and varies with different criteria of pressure front defined, i.e., the amount of pressure change from the initial formation pressure at the pressure front of the pressure disturbance area. As the dimensionless pressure defined at the pressure front changed from 0.1095 to 1.0E-9, the radius coefficient varied from 4 to 71.15. The radius coefficient was independent of the level of the flow rate for a well producing at a constant flow rate. For a well producing with variable flow rates, the radius coefficient is not a constant for the case of larger pressure drops defined at the pressure front. The skin factor does not affect the result of the calculated radius of investigation. The wellbore storage volume will affect the propagation of the radius of investigation only at an early time, depending on the wellbore storage volume. In a bounded reservoir, the dimensionless boundary effect time, i.e., the starting time of transient pressure affected by bounded reservoir, is a function of radius coefficient and geometry factor. The geometry factor is defined to consider the geometry shape of reservoir boundary and the location of the producing well. The values of geometry factor for various reservoir geometry shapes and well locations are derived. For a bounded circular reservoir with a well located at the center, the dimensionless boundary effect time is only a function of radius coefficient and independent on geometry factor. The results of this study show that the radius coefficient is 17.82 which is derived on the fact that the dimensionless boundary effect time estimated from the radius of investigation equation with radius coefficient of 17.82 is consistent with that from the deviated point of pressure type curves of infinite and finite reservoirs.