Comparison of Fractured-Horizontal-Well Performance in Tight Sand and Shale Reservoirs

2011 ◽  
Vol 14 (02) ◽  
pp. 248-259 ◽  
Author(s):  
E.. Ozkan ◽  
M Brown ◽  
R.. Raghavan ◽  
H.. Kazemi

Summary This paper presents a discussion of fractured-horizontal-well performance in millidarcy permeability (conventional) and micro- to nanodarcy permeability (unconventional) reservoirs. It provides interpretations of the reasons to fracture horizontal wells in both types of formations. The objective of the paper is to highlight the special productivity features of unconventional shale reservoirs. By using a trilinear-flow model, it is shown that the drainage volume of a multiple-fractured horizontal well in a shale reservoir is limited to the inner reservoir between the fractures. Unlike conventional reservoirs, high reservoir permeability and high hydraulic-fracture conductivity may not warrant favorable productivity in shale reservoirs. An efficient way to improve the productivity of ultratight shale formations is to increase the density of natural fractures. High natural-fracture conductivities may not necessarily contribute to productivity either. Decreasing hydraulic-fracture spacing increases the productivity of the well, but the incremental production gain for each additional hydraulic fracture decreases. The trilinear-flow model presented in this work and the information derived from it should help the design and performance prediction of multiple-fractured horizontal wells in shale reservoirs.

2021 ◽  
Author(s):  
Ruslan Rubikovich Urazov ◽  
Alfred Yadgarovich Davletbaev ◽  
Alexey Igorevich Sinitskiy ◽  
Ilnur Anifovich Zarafutdinov ◽  
Artur Khamitovich Nuriev ◽  
...  

Abstract This research presents a modified approach to the data interpretation of Rate Transient Analysis (RTA) in hydraulically fractured horizontal well. The results of testing of data interpretation technique taking account of the flow allocation in the borehole according to the well logging and to the injection tests outcomes while carrying out hydraulic fracturing are given. In the course of the interpretation of the field data the parameters of each fracture of hydraulic fracturing were selected with control for results of well logging (WL) by defining the fluid influx in the borehole.


2014 ◽  
Vol 962-965 ◽  
pp. 489-493
Author(s):  
Zhi Qiang Li ◽  
Yong Quan Hu ◽  
Wen Jiang Xu ◽  
Jin Zhou Zhao ◽  
Jian Zhong Liu ◽  
...  

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.


2021 ◽  
Author(s):  
Hongjie Xiong ◽  
Sangcheol Yoon ◽  
Yu Jiang

Abstract The multi-stage fracture treatments create complex fracture networks with various proppant type, size, and concentration distributed within and along fractures through reservoir rock, where larger size and higher concentrations usually result in higher long-term conductivity. To model the fracture conductivity reduction with depletion, we traditionally use a single monotonic relationship between fracture conductivity and pressure, which is proper for a single proppant concentration but obviously hard to describe the situation in the horizontal wells with complex concentration distributions. This paper is to present a new method to speed-up the calibration process of well performance models with multi-million cells and its two applications in the Wolfcamp reservoir in the Delaware Basin. To study well performance and completion effectiveness of 3000 horizontal wells over University Lands acreage in the Permian Basin, we have built a series of well performance models with complex fracture networks (SPE 189855 and 194367). We have used those models to methodically investigate the drivers of well completion parameters and well spacing on well performance and field development value (URTeC 554). In the process of building multiple robust well performance models, we found out it is hard and time-consuming to calibrate a well performance model with multi-million cells based upon a single correlation between fracture conductivity and pressure. We first modeled the complex fracture networks and fracture conductivity distributions based upon the historical completion pumping data; we then developed multiple correlations to characterize fracture conductivity reduction and closure behaviors with pressure depletion based upon initial fracture conductivities (as the result of proppant type, size, and concentration) and reservoir geomechanical properties. We found out that this method significantly reduced our model calibration time. We then applied our method to multiple case studies in the Permian Basin to test and improve the method. We have thus developed a method to mimic the fracture conductivity reduction and closure behavior in the horizontal wells with complex fracture networks. The paper will layout the theoretical foundation and detail our method to develop the multiple correlations to model fracture conductivity reduction and fracture closure behaviors in the horizontal well performance models in the unconventional reservoirs. We will then show two case studies to illustrate how we have applied our method to speed up the model calibration process. Based upon the multiple applications into our model calibration process, we have concluded that the method is very effective to calibrate the well performance model with complex fracture networks. The method can be used for engineers to simplify and speedup calibrating horizontal well performance models. Therefore, engineers can more effectively build more robust well performance models to optimize field development plans in the unconventional reservoirs.


2012 ◽  
Vol 524-527 ◽  
pp. 1310-1313
Author(s):  
Zhi Hong Zhao ◽  
Jian Chun Guo ◽  
Fan Hui Zeng

Due to the differences of stress and physical property in the pay zone, the fractured horizontal well may be different in length and azimuth angle. Furthermore, because of the mutual disturbance among fractures, the accurate prediction of production of fractured horizontal wells become more complicated. This paper presents a new model to predict the production of the fractured horizontal wells by considering the effects of fracture number, fracture length, fracture interval, fracture symmetry, azimuth angle and conductivity. Compared with the numerical simulation, this model needs less parameter and calculating time, and is easy to be applied to the designs of segmentation fracturing in horizontal wells. The model in this paper has been applied to the optimizing designs of hydraulic fracturing for two horizontal wells in North China oilfield and the predicted results agree with the actual production well.


2014 ◽  
Vol 644-650 ◽  
pp. 3379-3382
Author(s):  
Meng Xia Liu ◽  
Ju Hua Li ◽  
Lei Zhang

Conventional productivity research method of fractured horizontal wells doesn’t meticulously describe the seepage characteristics of the near wellbore area. Based on the similarity of seepage field and temperature field, and ANSYS finite element software platform, this paper conducts the simulation calculation of the fractured horizontal wells’ productivity, shows the flow of near wellbore area, and analyzes the factors affecting the productivity on fractured horizontal well by using the heat flow field model in the ANSYS software platform. The results show that the larger the angle between fractures and horizontal wells, the higher the production. It is necessary to place the fractures stagger to the greatest extent, and the fracture spacing should be extended as much as possible in actual production. This optimization design of fractured horizontal well has a certain role in guiding.


2021 ◽  
Vol 11 (4) ◽  
pp. 1873-1883
Author(s):  
P. Q. Lian ◽  
C. Y. Ma ◽  
T. Z. Duan ◽  
H. W. Zhao

AbstractThe development of multistage fracturing technology in horizontal wells is a great impulsion to the successful development of unconventional resources. The hydraulic fractures distribute regularly along the horizontal wellbore, forming a seepage channel for fluids in tight gas reservoir and greatly improving the productivity of horizontal wells. Based on Green function and Neumann product principle, we establish a flow model of fractured horizontal well coupled with anisotropic tight gas reservoir under both unsteady state and pseudo-steady state and propose a method to solve this model. The calculation results show that flow rate of horizontal well under the early unsteady state is larger than that under the pseudo-steady state. There is no interference among fractures in the early unsteady state, and flow rate is in direct proportion to fracture numbers. Affected by frictional and acceleration pressure drop, flow rate of the end fractures is obviously larger than other fractures in pseudo-steady state. The permeabilities in different directions have great influence on well flow rate distribution. With the increasing Kx, the interference between the fractures is reduced, and the flow distribution is more balanced. When Ky becomes larger, the interference between fractures are stronger, and the “U” shape distribution of the wellbore flow is more significant.


Author(s):  
Yong Wang ◽  
Xiangyi Yi

AbstractCarbonate reservoir is one kinds of important reservoir in the world. Because of the characteristics of carbonate reservoir, horizontal well, and acid fracturing became a key technology for efficiently developing carbonate reservoir. Establishing corresponding mathematical models and analyzing transient pressure behaviors of this type of well-reservoir configuration can provide a better understanding of fluid flow patterns in formation as well as estimations of important parameters. A coupling mathematical model for a fractured horizontal well in triple media carbonate reservoir with three kinds of reservoir outer boundaries by conceptualizing vugs as spherical shapes is presented in this article, in which the infinite conductivity of the acid fractures is taken into account. A semi-analytical solution is obtained in the Laplace domain by using source function theory, Laplace transformation, discretization of fracture, and superposition principle. Analysis of transient pressure responses indicates that several characteristic flow periods of fractured horizontal wells in triple media carbonate reservoir can be identified. Parametric analysis shows that fracture half-length, fracture number, fracture spacing, conditions of reservoir outer boundary, and so on can significantly influence the transient pressure responses of fractured horizontal wells in triple media carbonate reservoir. The model presented in this article can be applied to obtain important parameters pertinent to reservoir or fracture by type curve matching, and it can also provide useful information for optimizing fracture parameters.


Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1498 ◽  
Author(s):  
Qing Tian ◽  
Yudong Cui ◽  
Wanjing Luo ◽  
Pengcheng Liu ◽  
Bo Ning

Horizontal wells with multi-stage fractures have been widely used to improve coalbed methane (CBM) production from coalbed methane reservoirs. The main focus of this work is to establish a new semi-analytical method in the Laplace domain and investigate the transient pressure behavior in coalbed methane reservoirs. With the new semi-analytical method, flow regimes of a multi-fractured horizontal well in coalbed methane reservoirs were identified. In addition, the sensitivities of fracture conductivity, diffusion model, storability ratio, inter-porosity flow coefficient, adsorption index, fracture spacing, fracture asymmetry, non-planar angle, and wellbore storage were studied. Results indicate that six characteristic flow regimes can be identified for multi-fractured horizontal wells in coalbed methane reservoirs, which are bilinear flow, first linear flow, desorption-diffusion flow, first pseudo-radial flow, second linear flow, and second pseudo-radial flow. Furthermore, the sensitivity analysis shows that the early flow is mainly determined by the fracture conductivity, the asymmetry factor, the non-planar angle, and the wellbore storage; while the desorption-diffusion flow regime is mainly influenced by the diffusion model, the storability ratio, the inter-porosity flow coefficient, the adsorption index, and the fracture spacing. Our work can provide a deep insight into the fluid flow mechanism of multi-fractured horizontal wells in coalbed methane reservoirs.


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