Pressure Transient Analysis for Horizontal Well and Multi-Branched Horizontal Wells

1996 ◽  
Author(s):  
X.Y. Kong ◽  
X.Z. Xu ◽  
D.T. Lu
Keyword(s):  
Transient Analysis ◽  
Horizontal Well ◽  
Horizontal Wells ◽  
Pressure Transient Analysis ◽  
Pressure Transient

Pressure-Transient Responses of Horizontal and Curved Wells in Anticlines and Domes

2007 ◽  
Vol 10 (01) ◽  
pp. 66-76 ◽  
Author(s):  
Nasser Saqer Al-Mohannadi ◽  
Erdal Ozkan ◽  
Hossein Kazemi
Keyword(s):  
Transient Analysis ◽  
Horizontal Well ◽  
Vertical Plane ◽  
Flow Characteristics ◽  
Horizontal Wells ◽  
Transient Responses ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Well Trajectory ◽  
Anisotropic Reservoirs

Summary This paper presents a discussion of the pressure-transient responses of horizontal wells in anticlinal structures and curved and undulating wells in slab reservoirs. It confirms that, in the absence of a gas cap, conventional horizontal-well models may be used to approximate the flow characteristics of the systems in which the trajectory of the well does not conform to the curvature of the producing structure. If a gas cap is present, however, the unconformity of the well trajectory and producing layer manifests itself, especially on derivative characteristics when the gas saturation increases around the well. In general, the most significant deviations from the conventional horizontal-well behavior are observed during the buildup periods following long drawdowns. In these cases, the pressure-transient analysis is complicated and requires detailed numerical modeling of the well trajectory and reservoir geometry in the vertical plane. Introduction Conventional horizontal-well pressure-transient models assume that the top and bottom boundaries of the reservoir are horizontal planes; that is, the producing stratum is a slab, and the well is straight and parallel to the slab boundaries. Wells, however, may be drilled horizontally in anticlines and domes, or they may be curved or undulating in a horizontal slab reservoir. In the literature, several reservoir shapes have been considered in the context of horizontal wells: infinite slab (Clonts and Ramey 1986; Ozkan et al. 1989; Goode and Thambynayagam 1987; Rosa and Carvalho 1989; Kuchuk et al. 1990, 1991; Ozkan and Raghavan 1990a), cylinder (Ozkan and Raghavan 1991a, 1991b), rectangular parallelepiped (Ozkan and Raghavan 1991a, 1991b; Daviau et al. 1988; Odeh and Babu 1990), and vertical no-flow boundary at an arbitrary orientation (Azar-Nejad et al. 1996a). The common feature of these reservoir models is the assumption that the top and bottom boundaries are horizontal planes. Despite the fact that the conditions at the top and bottom boundaries strongly influence the pressure-transient characteristics of horizontal wells (Clonts and Ramey 1986; Ozkan et al. 1989; Goode and Thambynayagam 1987; Ozkan 2001), the effect of the curvature of these boundaries, as in the case of anticlines and domes, has not been discussed in the literature. Similar to the curvature of the top and bottom boundaries, the curvature or undulations of horizontally oriented wells (referred to as horizontal wells in this paper) have not attracted much attention in the pressure-transient-analysis literature. Two studies have addressed this issue specifically. Azar-Nejad et al. (1996b) considered a curved well that was a quarter of a circle (from vertical to horizontal) in a slab reservoir. They showed that especially in anisotropic reservoirs, the pressure-transient response of the curved well could not be approximated by that of a straight horizontal well of equal drilled length. This study did not address the issue of effective well length and the effect of the aspect ratio (the ratio of the distance from the well to the closest boundary and thickness of the formation). Goktas and Ertekin (2003) discussed another common problem for horizontal wells—undulations. Their study indicated that when the vertical window of undulations becomes comparable to the formation thickness, undulations might influence the characteristics of pressure-transient responses. For practical windows of undulations that commonly result from standard drilling practices, however, the pressure-transient responses could be closely approximated by that of a straight horizontal well. This conclusion was different from that of Azar-Nejad et al. (1996b). It also must be noted that Goktas and Ertekin (2003) used the straight distance between the tips of the undulating well in the comparisons with straight horizontal wells, as opposed to the total drilled length used by Azar-Nejad et al. (1996b).

A Finite-Conductivity Horizontal-Well Model for Pressure-Transient Analysis in Multiple-Fractured Horizontal Wells

SPE Journal ◽  
2017 ◽  
Vol 22 (04) ◽  
pp. 1112-1122 ◽  
Author(s):  
Zhiming Chen ◽  
Xinwei Liao ◽  
Xiaoliang Zhao ◽  
Xiangji Dou ◽  
Langtao Zhu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Transient Analysis ◽  
Horizontal Well ◽  
Horizontal Wells ◽  
Model Verification ◽  
Finite Conductivity ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Fractured Horizontal Wells

Summary In this paper, we propose a new model for pressure-transient analysis in multiple-fractured horizontal wells (MFHWs) with consideration of pressure drop along the wellbore. To make the physical model better understood, the whole formation is divided into three parts: (1) reservoir, (2) fracture, and (3) wellbore. With incorporating frictional and acceleration pressure drops, a mathematical model with a finite-conductivity horizontal well (FCHW) is developed. Newton-Raphson iterations are used to solve the mathematical model and obtain the transient-pressure solutions of the MFHW. Model verification is performed by comparing with the solutions from a numerical software. On the basis of the field cases from the Ordos Basin, performance prediction, sensitivity analysis, type-curve matching, and evaluations of uncertainty parameters are conducted. Results show that the contribution of wellbore hydraulics to the total pressure drop increases first and then decreases after reaching the peak value. Ignoring wellbore hydraulics would cause erroneous results during the well-performance forecast. In addition, the dimensionless wellbore pressure of the MFHW increases with an increase in Reynolds number (Re); it decreases as the reservoir/wellbore constant (ChD) increases. Furthermore, the impact of pressure drop on the pressure performance of the MFHW becomes more serious with the increasing Re or the decreasing ChD.

Revision of Pressure Transient Analysis in Mature Condensate-Rich Tight Gas Fields in Sultanate of Oman

2022 ◽  
Author(s):  
Ahmed Elsayed Hegazy ◽  
Mohammed Rashdi
Keyword(s):  
Transient Analysis ◽  
Horizontal Wells ◽  
Development Planning ◽  
Reservoir Modeling ◽  
Sultanate Of Oman ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Full Field ◽  
Gas Fields ◽  
Half Length

Abstract Pressure transient analysis (PTA) has been used as one of the important reservoir surveillance tools for tight condensate-rich gas fields in Sultanate of Oman. The main objectives of PTA in those fields were to define the dynamic permeability of such tight formations, to define actual total Skin factors for such heavily fractured wells, and to assess impairment due to condensate banking around wellbores. After long production, more objectives became also necessary like assessing impairment due to poor clean-up of fractures placed in depleted layers, assessing newly proposed Massive fracturing strategy, assessing well-design and fracture strategies of newly drilled Horizontal wells, targeting the un-depleted tight layers, and impairment due to halite scaling. Therefore, the main objective of this paper is to address all the above complications to improve well and reservoir modeling for better development planning. In order to realize most of the above objectives, about 21 PTA acquisitions have been done in one of the mature gas fields in Oman, developed by more than 200 fractured wells, and on production for 25 years. In this study, an extensive PTA revision was done to address main issues of this field. Most of the actual fracture dynamic parameters (i.e. frac half-length, frac width, frac conductivity, etc.) have been estimated and compared with designed parameters. In addition, overall wells fracturing responses have been defined, categorized into strong and weak frac performances, proposing suitable interpretation and modeling workflow for each case. In this study, more reasonable permeability values have been estimated for individual layers, improving the dynamic modeling significantly. In addition, it is found that late hook-up of fractured wells leads to very poor fractures clean out in pressure-depleted layers, causing the weak frac performance. In addition, the actual frac parameters (i.e. frac-half-length) found to be much lower than designed/expected before implementation. This helped to improve well and fracturing design and implementation for next vertical and horizontal wells, improving their performances. All the observed PTA responses (fracturing, condensate-banking, Halite-scaling, wells interference) have been matched and proved using sophisticated single and sector numerical simulation models, which have been incorporated into full-field models, causing significant improvements in field production forecasts and field development planning (FDP).

Field Cases of Horizontal Well Pressure Transient Analysis in West Africa

1996 ◽  
Author(s):  
Marcel J. Bourgeois ◽  
Jean-Luc Boutaud de la Combe ◽  
Renaud M. Deboaisne
Keyword(s):  
West Africa ◽  
Transient Analysis ◽  
Horizontal Well ◽  
Pressure Transient Analysis ◽  
Pressure Transient
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