An Improved Technique for Estimating Permeability, Fracture Length, and Fracture Conductivity From Pressure-Buildup Tests in Low-Permeability Gas Wells

1983 ◽  
Vol 35 (05) ◽  
pp. 981-990 ◽  
Author(s):  
S.A. Holditch ◽  
W.J. Lee ◽  
S.R. Gist
Keyword(s):  
Low Permeability ◽  
Gas Wells ◽  
Fracture Conductivity ◽  
Pressure Buildup ◽  
Fracture Length ◽  
Improved Technique

scholarly journals A new approach to finding effective parameters controlling the performance of multi-stage fractured horizontal wells in low-permeability heavy-oil reservoirs using RSM technique

2020 ◽  
Vol 10 (8) ◽  
pp. 3569-3586
Author(s):  
Armin Shirbazo ◽  
Jalal Fahimpour ◽  
Babak Aminshahidy
Keyword(s):  
Heavy Oil ◽  
Net Present Value ◽  
Low Permeability ◽  
Well Performance ◽  
Effective Parameters ◽  
Well Productivity ◽  
Fracture Conductivity ◽  
Fracture Length ◽  
Fracture Parameters ◽  
Multi Stage

Abstract The application of multi-stage fractured horizontal well (MSFHW) due to its costly operation necessitates optimization of associated fracture parameters to ensure its economic success. In comparison to significant number of studies dedicated to use of MSFHWs for shale gas reservoirs, there are only few researches available for oil systems. This study explores the optimum criteria for a number of important fracture parameters in low-permeability heavy-oil systems. For this purpose, a response surface methodology (RSM) was employed to examine the simultaneous effect of four fracture parameters, including the number of fracture stages, fracture length, fracture width and fracture conductivity, on well productivity. The evaluations were conducted on two homogeneous and heterogeneous permeability systems. The optimization of fracture parameters was also performed on an economic basis by utilizing the net present value (NPV) concept. Useful charts were also generated providing practical insights into the individual and combinational effects of fracture parameters on well performance. The results from this study demonstrated that the fracture conductivity and the number of fracture stages were, respectively, the first two important parameters controlling the well productivity for rock systems with higher permeability. However, when rock texture became tighter, the number, and to a lesser extent the length, of fractures exhibited more evident role on production improvement, especially in the case of heterogeneous reservoirs. The results also underlined the significance of economic considerations, in particular, when determining the optimum fracture length and number of fracture stages.

scholarly journals New prediction method for transient productivity of fractured five-spot patterns in low permeability reservoirs at high water cut stages

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 499-508
Author(s):  
Chuanzhi Cui ◽  
Zhongwei Wu ◽  
Zhen Wang ◽  
Jingwei Yang ◽  
Yingfei Sui
Keyword(s):  
Prediction Method ◽  
Mass Conservation ◽  
High Water ◽  
Low Permeability ◽  
Element Analysis ◽  
Fracture Length ◽  
High Water Cut Stage ◽  
High Water Cut ◽  
Water Cut ◽  
Low Permeability Reservoirs

AbstractPredicting the productivity of fractured five-spot patterns in low permeability reservoirs at high water cut stages has an important significance for the development and optimization of reservoirs. Taking the reservoir heterogeneity and uneven distribution of the remaining oil into consideration, a novel method for predicting the transient productivity of fractured five-spot patterns in low permeability reservoirs at high water cut stages is proposed by using element analysis, the flow tube integration method, and the mass conservation principle. This new method is validated by comparing with actual production data from the field and the results of a numerical simulation. Also, the effects of related parameters on transient productivity are analyzed. The results show that increasing fracture length, pressure difference and reservoir permeability correspond to an increasing productivity. The research provides theoretical support for the development and optimization of fractured five-spot patterns at the high water cut stage.

Parameters Optimization of Fractures with One for Injection and Two Others for Production of Horizontal Wells Fracturing on Offshore Oilfields

2014 ◽  
Vol 962-965 ◽  
pp. 489-493
Author(s):  
Zhi Qiang Li ◽  
Yong Quan Hu ◽  
Wen Jiang Xu ◽  
Jin Zhou Zhao ◽  
Jian Zhong Liu ◽  
...  
Keyword(s):  
Horizontal Well ◽  
Oil Production ◽  
Horizontal Wells ◽  
Simulation Method ◽  
Parameters Optimization ◽  
Development Mode ◽  
Fracture Conductivity ◽  
Fracture Length ◽  
Fractured Horizontal Well ◽  
Production Research

This article presents a new exploitation method based on the same fractured horizontal well with fractures for injection or production on offshore low permeability oilfields for the purpose of adapting to their practical situations and characteristics, which means fractures close to the toe of horizontal well used for injecting water and fractures near the heel of horizontal well used for producing oil. According to proposed development mode of fracturing, relevant physical model is established, Then reservoir numerical simulation method has been applied to study the effect of arrangement pattern of injection and production fractures, fracture conductivity, fracture length on oil production. Research indicates cumulative oil production is much higher by employing the middle fracture for injecting water compared with using the remote one, suggesting that the middle fracture adopted for injecting water, and hydraulic fracture length and conductivity have been optimized. The proposed development pattern of a staged fracturing for horizontal wells with some fractures applied for injecting water and others for production based on the same horizontal well provides new thoughts for offshore oilfields exploitation.

Identification of Productive Layers in Low-Permeability Gas Wells

1992 ◽  
Vol 44 (11) ◽  
pp. 1240-1248 ◽  
Author(s):  
J.L. Johnston ◽  
W.J. Lee
Keyword(s):  
Low Permeability ◽  
Gas Wells

Mitigation of Annulus Pressure Buildup in Offshore Gas Wells by Determination of Top of Cement

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Alex W. Mwang’ande ◽  
Hualin Liao ◽  
Long Zeng
Keyword(s):  
Field Data ◽  
Gas Wells ◽  
Gas Well ◽  
Pressure Buildup ◽  
Cheap Method ◽  
Calculation Results ◽  
Sustained Casing Pressure ◽  
Casing Pressure ◽  
Mitigation Methods

Annulus pressure buildup (APB) is still a serious problem in offshore gas wells, which threatens the safety of wells for the entire phases of drilling, completion, and production. The existing methods for mitigating APB are technically complex and highly costly. Setting top of cement (TOC) below the outer casing shoe to mitigate APB is easy to implement and can significantly reduce costs. However, there are no unified methods of determining TOC for this purpose. Nevertheless, existing petroleum standards give ambiguous regulations on the setting of TOC. This article brings a new and cheap method of mitigating APB by determining best TOC settings using a mathematical model for calculating APB from both annulus fluid expansion (AFE) and sustained casing pressure (SCP). Field data from gas well X are inputted to the model to describe how it serves this purpose. Calculation results for well X show that setting TOC's above and below the upper casing shoes for production and intermediate casings annuli, respectively, can greatly avoid the problem of APB and the costs associated with the existing mitigation methods. This technique can be used to other wells following the same procedures. The developed model reduced greatly the ambiguity of TOC determination as it helps to get the clear TOC combinations that control APB at the lowest cost of well construction while maintaining good and safe well operation.

Stabilized Productivity of a Hydraulically Fractured Well Producing at Constant Pressure

SPE Journal ◽  
2006 ◽  
Vol 11 (01) ◽  
pp. 120-131 ◽  
Author(s):  
Jacques Hagoort
Keyword(s):  
Flow Conditions ◽  
Productivity Improvement ◽  
Fracture Conductivity ◽  
Fracture Length ◽  
State Flow ◽  
Production Improvement ◽  
Constant Rate ◽  
Infinite Conductivity ◽  
State Production ◽  
Fractured Well

Summary This paper describes a simple and easy-to-construct numerical model for the calculation of the stabilized productivity of a hydraulically fractured well producing at a constant well pressure. The model takes into account both Darcy and non-Darcy pressure losses in the fracture. Dimensionless charts are presented that illustrate productivity improvement as a function of fracture length, fracture conductivity, and non-Darcy flow. For dimensionless fracture lengths in excess of 0.2, constant-pressure productivities are significantly lower than constant-rate productivities as predicted, for example, by the McGuire-Sikora productivity improvement chart. The maximum difference is 20% for an infinite-conductivity fracture with a length of unity. Both fracture conductivity and non-Darcy flow adversely affect well productivity; the reduction in productivity is larger for longer fractures. Introduction The productivity of a well is commonly expressed by a productivity index defined as the ratio of production rate and difference between average reservoir pressure and well pressure. Stabilized productivity refers to production from a well in the semisteady-state flow regime (i.e., the regime beyond the initial transient regime), during which flow in the reservoir is dominated by the reservoir boundaries. In the past, most studies on the stabilized productivity of hydraulically fractured wells were about steady-state production or semisteady-state production at a constant rate. As we shall demonstrate in this paper, the type of well boundary condition has a significant effect on productivity, especially for long fractures. For production by pressure depletion, characterized by declining production rates, constant well pressure is a more appropriate boundary condition. In the late 1950s, McGuire and Sikora (1960) presented a productivity improvement chart for fully penetrating fractured wells producing at a constant rate under semisteady-state flow conditions based on electrical analog model experiments. The chart shows production improvement vs. fracture conductivity for various fracture lengths. The McGuire-Sikora chart is a classic in the fracturing literature and is being used to this day. In the early 1960s, Prats (1961) presented a theoretical study on the productivity of a fully penetrating fractured well under steady-state flow conditions. He showed that the effect of a fracture can be represented by an apparent or effective wellbore radius, which depends on fracture length and fracture conductivity. For fractures that are relatively small and have an infinite conductivity, the effective wellbore radius is equal to half the fracture half-length. In a follow-up study, Prats et al. (1962) demonstrated that this result also holds for stabilized flow of a slightly compressible liquid. In the mid-1970s, Holditch presented a production improvement chart (included in Lee 1989) based on experiments with a numerical reservoir simulator, which essentially confirmed the earlier results of McGuire and Sikora. Although based on production at constant rate, the McGuire-Sikora and Holditch charts are also being used for production at declining production rates (Lee 1989).

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