Assessment of Total Skin Factor in Perforated Wells

Abstract

In this study, the available methods and software to predict the well productivity and total skin factor in fully perforated vertical wells have been reviewed. The methods have been compared against the experimental data obtained on an electrolytic apparatus, and their accuracy has been investigated. It has been observed that the 3D semianalytical model, SPAN 6.0 software, and the simple hybrid model described in this paper replicate the experimental results very well. On the other hand, the results estimated from the McLeod method and the Karakas-Tariq method substantially deviate from the experimental data; hence, these models/methods should be used with caution.The literature hosts many equations to predict the total skin factor in partially perforated vertical wells. Some of the available models have been tested against the results from the 3D semianalytical model. It has been shown that total skin-factor equations based on the summation of individual components do not work. The 3D semianalytical model has been modified to build an approximate model for fully and partially perforated inclined wells in isotropic formations. Additionally, a simple hybrid model to compute total skin factor in perforated inclined wells has been presented. The hybrid model for perforated inclined wells agrees well with the approximate 3D model. Some of the available models to calculate total skin factor in perforated inclined wells have been compared to the approximate 3D model, and their accuracy has been discussed.Finally, a simple model to predict total skin factors in perforated horizontal wells has been developed. The application using the simple model has demonstrated that a combination of long wellbore length and perforations bypassing the damaged zone could overcome the destructive effect of severe formation damage around the wellbore.

Pressure Transient Solutions for Vertically Slotted-Partially Penetrated Vertical Wells in Porous Media

“…They compared their solutions with the middle point, equivalent-pressure point, and pressure-averaging solutions given in the petroleum literature. In addition to the recent Biryukov and Kuchuk (2012) paper, a few other papers were also published on selectively perforated and/or completed wells, i.e., wells with multiple production slots (ring slots along the wellbore), specially Spivak and Horne (1983), Larsen (1993), Yildiz and Cinar (1998), Tang et al (2000), Yildiz (2002aYildiz ( , b, 2004Yildiz ( , 2006a. The Spivak and Horne (1983) vertically slotted-liner solution, which is obtained from the uniform-flux solution, is somewhat similar to the solutions given in this paper.…”

Perforated Completion Optimization Using a New, Enhanced and Integrated Perforating Job Design Tool

“…These numerical simulations culminated in the semi-analytical productivity solution developed by Karakas and Tariq (1991). Although several notable efforts were made to improve the model with numerical and analytical solutions (Dugolu, 1998;Anseh et al 2002;Yildiz, 2006;Atkinson et al 2009;Sun et al 2011), no major issues have been identified. A few discrepancies between the model and numerical simulation results were primarily because of different, usually unrealistic, assumptions used in the numerical simulations rather than defects of the semi-analytical model.…”

A Simple Approximate Method to Predict Inflow Performance of Selectively Perforated Vertical Wells

“…The flow efficiency of the FPWs has been the subject of many investigations. [13][14][15][16][17][18][19][20][21][22][23][24][25] The effect of ideal perforating has been quantified in terms of perforation pseudoskin, .…”

“…24 Recently, the McLeod method, the Karakas-Tariq algorithm, Jones-Slusser method, SPAN software, and the 3D analytical solution were compared against the experimental data. 25 It has been shown that 1) the McLeod method underestimates the perforation total skin, 2) the Karakas-Tariq method for perforation pseudoskin works fine, however, the Karakas-Tariq algorithm overpredicts perforation total skin in the presence of formation damage and crushed zone, 3) the 3D analytical solution and SPAN software replicate the experimental data very well, and 4) the Jones-Slusser model, which does not consider the effect of compacted zone, agrees well with the 3D analytical solution and SPAN software when the crushed zone is also ignored in the 3D solution and SPAN.…”

“…25, a modified version of the Jones-Slusser method, accounting for the skin factor due to rock compaction around the perforation tunnels, has been proposed. The modified Jones-Slusser method could be analytically derived if it is assumed that the perforations are terminated inside the damaged zone and a radial flow geometry exists beyond the damaged zone.…”