Semi-Analytical Rate Decline Solutions for a Refractured Horizontal Well Intercepted by Multiple Reorientation Fractures with Fracture Face Damage in an Anisotropic Tight Reservoir

Refracturing treatment is an economical way to improve the productivity of poorly or damaged fractured horizontal wells in tight reservoirs. Fracture reorientation and fracture face damage may occur during refracturing treatment. At present, there is still no report on the rate decline solution for refractured horizontal wells in tight reservoirs. In this work, by taking a semi-analytical method, traditional rate decline and Blasingame-type rate decline solutions were derived for a refractured horizontal well intercepted by multiple reorientation fractures with fracture face damage in an anisotropic tight reservoir. The accuracy and reliability of the traditional rate decline solution were verified and validated by comparing it with a classic case in the literature and a numerical simulation case. The effects of fracture reorientation and fracture face damage on the rate decline were investigated in depth. These investigations demonstrate that fracture face damage is not conducive to increasing well productivity during the early flow period and there is an optimal matching relationship between the principal fracture section angle and permeability anisotropy, particularly for the reservoirs with strong permeability anisotropy. The fracture length ratio and fracture spacing have a weak effect on the production rate and cumulative production while the fracture number shows a strong influence on the rate decline. Furthermore, multifactor sensitivity analysis indicates that fracture conductivity has a more sensitive effect on well productivity than fracture face damage, implying the importance of improving fracture conductivity. Finally, a series of Blasingame-type rate decline curves were presented, and type curve fitting and parameter estimations for a field case were conducted too. This work deepens our understanding of the production performance of refractured horizontal wells, which helps to identify reorientation fracture properties and evaluate post-fracturing performance.

Download Full-text

A practical method for planning large number of horizontal wells with a reservoir model for a field development plan

Petrovietnam Journal ◽

10.47800/pvj.2021.10-02 ◽

2021 ◽

Vol 10 ◽

pp. 17-32

Author(s):

Guido Fava ◽

Việt Anh Đinh

Keyword(s):

Horizontal Well ◽

Horizontal Wells ◽

Simulation Software ◽

Production Performance ◽

Development Plan ◽

Regular Pattern ◽

Production Forecast ◽

Advanced Technique ◽

Large Reservoir ◽

Field Development

The most advanced technique to evaluate different solutions proposed for a field development plan consists of building a numerical model to simulate the production performance of each alternative. Fields covering hundreds of square kilometres frequently require a large number of wells. There are studies and software concerning optimal planning of vertical wells for the development of a field. However, only few studies cover planning of a large number of horizontal wells seeking full population on a regular pattern. One of the criteria for horizontal well planning is selecting the well positions that have the best reservoir properties and certain standoffs from oil/water contact. The wells are then ranked according to their performances. Other criteria include the geometry and spacing of the wells. Placing hundreds of well individually according to these criteria is highly time consuming and can become impossible under time restraints. A method for planning a large number of horizontal wells in a regular pattern in a simulation model significantly reduces the time required for a reservoir production forecast using simulation software. The proposed method is implemented by a computer script and takes into account not only the aforementioned criteria, but also new well requirements concerning existing wells, development area boundaries, and reservoir geological structure features. Some of the conclusions drawn from a study on this method are (1) the new method saves a significant amount of working hours and avoids human errors, especially when many development scenarios need to be considered; (2) a large reservoir with hundreds of wells may have infinite possible solutions, and this approach has the aim of giving the most significant one; and (3) a horizontal well planning module would be a useful tool for commercial simulation software to ease engineers' tasks.

Download Full-text

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.962-965.489 ◽

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.

Download Full-text

Evaluating the Performance of Horizontal Multi-Frac Wells in a Depleted Gas Condensate Reservoir in Sultanate of Oman

10.2118/205328-ms ◽

2022 ◽

Author(s):

Josef R. Shaoul ◽

Jason Park ◽

Andrew Boucher ◽

Inna Tkachuk ◽

Cornelis Veeken ◽

...

Keyword(s):

Horizontal Well ◽

Horizontal Wells ◽

Gas Condensate ◽

Integrated Analysis ◽

Single Fracture ◽

Reservoir Pressure ◽

Well Test ◽

Vertical Wells ◽

Fracture Conductivity ◽

Half Length

Abstract The Saih Rawl gas condensate field has been producing for 20 years from multiple fractured vertical wells covering a very thick gross interval with varying reservoir permeability. After many years of production, the remaining reserves are mainly in the lowest permeability upper units. A pilot program using horizontal multi-frac wells was started in 2015, and five wells were drilled, stimulated and tested over a four-year period. The number of stages per horizontal well ranged from 6 to 14, but in all cases production was much less than expected based on the number of stages and the production from offset vertical wells producing from the same reservoir units with a single fracture. The scope of this paper is to describe the work that was performed to understand the reason for the lower than expected performance of the horizontal wells, how to improve the performance, and the implementation of those ideas in two additional horizontal wells completed in 2020. The study workflow was to perform an integrated analysis of fracturing, production and well test data, in order to history match all available data with a consistent reservoir description (permeability and fracture properties). Fracturing data included diagnostic injections (breakdown, step-rate test and minifrac) and main fracture treatments, where net pressure matching was performed. After closure analysis (ACA) was not possible in most cases due to low reservoir pressure and absence of downhole gauges. Post-fracture well test and production matching was performed using 3D reservoir simulation models including local grid refinement to capture fracture dimensions and conductivity. Based on simulation results, the effective propped fracture half-length seen in the post-frac production was extremely small, on the order of tens of meters, in some of the wells. In other wells, the effective fracture half-length was consistent with the created propped half-length, but the fracture conductivity was extremely small (finite conductivity fracture). The problems with the propped fractures appear to be related to a combination of poor proppant pack cleanup, low proppant concentration and small proppant diameter, compounded by low reservoir pressure which has a negative impact on proppant regained permeability after fracturing with crosslinked gel. Key conclusions from this study are that 1) using the same fracture design in a horizontal well with transverse fractures will not give the same result as in a vertical well in the same reservoir, 2) the effect of depletion on proppant pack cleanup in high temperature tight gas reservoirs appears to be very strong, requiring an adjustment in fracture design and proppant selection to achieve reasonable fracture conductivity, and 3) achieving sufficient effective propped length and height is key to economic production.

Download Full-text

Pressure Transient Performance for a Horizontal Well Intercepted by Multiple Reorientation Fractures in a Tight Reservoir

Energies ◽

10.3390/en12224232 ◽

2019 ◽

Vol 12 (22) ◽

pp. 4232 ◽

Cited By ~ 1

Author(s):

Guoqiang Xing ◽

Shuhong Wu ◽

Jiahang Wang ◽

Mingxian Wang ◽

Baohua Wang ◽

...

Keyword(s):

Horizontal Well ◽

Flow Behavior ◽

Flow Equation ◽

Finite Conductivity ◽

Transient Pressure ◽

Pressure Derivative ◽

Fracture Conductivity ◽

Fracture Spacing ◽

Economic Production ◽

Tight Reservoir

A fractured horizontal well is an effective technology to obtain hydrocarbons from tight reservoirs. In this study, a new semi-analytical model for a horizontal well intercepted by multiple finite-conductivity reorientation fractures was developed in an anisotropic rectangular tight reservoir. Firstly, to establish the flow equation of the reorientation fracture, all reorientation fractures were discretized by combining the nodal analysis technique and the fracture-wing method. Secondly, through coupling the reservoir solution and reorientation fracture solution, a semi-analytical solution for multiple reorientation fractures along a horizontal well was derived in the Laplace domain, and its accuracy was also verified. Thirdly, typical flow regimes were identified on the transient-pressure curves. Finally, dimensionless pressure and pressure derivative curves were obtained to analyze the effect of key parameters on the flow behavior, including fracture angle, permeability anisotropy, fracture conductivity, fracture spacing, fracture number, and fracture configuration. Results show that, for an anisotropic rectangular tight reservoir, horizontal wells should be deployed parallel to the direction of principal permeability and fracture reorientation should be controlled to extend along the direction of minimum permeability. Meanwhile, the optimal fracture number should be considered for economic production and the fracture spacing should be optimized to reduce the flow interferences between reorientation fractures.

Download Full-text

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

SPE Reservoir Evaluation & Engineering ◽

10.2118/121290-pa ◽

2011 ◽

Vol 14 (02) ◽

pp. 248-259 ◽

Cited By ~ 196

Author(s):

E.. Ozkan ◽

M Brown ◽

R.. Raghavan ◽

H.. Kazemi

Keyword(s):

Hydraulic Fracture ◽

Horizontal Well ◽

Flow Model ◽

Horizontal Wells ◽

Natural Fracture ◽

Well Performance ◽

Fracture Conductivity ◽

Fractured Horizontal Well ◽

Shale Reservoirs ◽

Fractured Horizontal Wells

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.

Download Full-text

Novel Completion Designs in Horizontal Well with Transverse Hydraulic Fractures for Enhanced Recovery in Unconventional or Tight Reservoirs

10.2118/206368-ms ◽

2021 ◽

Author(s):

Shubham Mishra ◽

Christopher Fredd ◽

Dean Wilberg ◽

Umur Yanbollu

Keyword(s):

Oil Recovery ◽

Hydraulic Fracture ◽

Enhanced Recovery ◽

Horizontal Wells ◽

Face Alignment ◽

Hydraulic Fractures ◽

Fracture Face ◽

Face To Face ◽

Tight Reservoirs ◽

Transverse Fractures

Abstract Low recovery, 2 to 15%, in unconventional plays (including tight reservoirs and source rocks) has long been recognized as a business deterrent. The industry applies enhanced oil recovery (EOR) techniques, along with hydraulic fractures in tight/unconventional plays, to improve the recovery. To maximize matrix sweep, the fractures are aligned in a face-to-face assembly. Such an arrangement can be achieved using vertical or longitudinal hydraulic fracture on horizontal wells, but these, generally, do not provide as effective reservoir contact (hydraulic fracture surface area) as horizontal wells with multistage transverse hydraulic fractures. The multistage transverse hydraulic fracture, however, comes at the costs of conformance issues with early water breakthrough from short-circuiting and inability to achieve fracture face-to-fracture face alignment of the injection and production fractures. The vast majority of wells drilled in unconventional plays are in the transverse configuration; hence, there is a need for an optimal solution for transverse fractures combined with improved oil recovery (IOR)/EOR approaches. In this work, we introduce the multistage enhanced recovery (MS-ER) techniques that enable face-to-face alignment for optimal enhanced hydrocarbon recovery/IOR/EOR in horizontal wells with multistage transverse fractures, thereby enabling optimal recovery and mitigating the key risk of fracture short-circuiting.

Download Full-text

Productivity Evaluation for Long Horizontal Well Test in Deep-Water Faulted Sandstone Reservoir

Geofluids ◽

10.1155/2020/8845270 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Zhiwang Yuan ◽

Li Yang ◽

Yingchun Zhang ◽

Rui Duan ◽

Xu Zhang ◽

...

Keyword(s):

Steady State ◽

Deep Water ◽

Horizontal Well ◽

Evaluation Method ◽

Horizontal Wells ◽

Productivity Index ◽

Test Time ◽

Well Test ◽

Well Productivity ◽

Sandstone Reservoir

For deep-water faulted sandstone reservoirs, the general practice is to design long horizontal wells improving well productivity. During the project implementation stage, well tests are performed on all drilled wells to evaluate well productivity accurately. Furthermore, multisize chokes are often utilized in a shorten test time for loosen formation, high test cost, and high well productivity. Nevertheless, the conventional productivity evaluation approach cannot accurately evaluate the well test productivity and has difficulty in determining the underneath pattern. As a result, the objective of this paper is to determine a productivity evaluation method for multisize chokes long horizontal well test in deep-water faulted sandstone reservoir. This approach introduces a productivity model for long horizontal wells in faulted sandstone reservoir. It also includes the determination of steady-state test time and the productivity evaluation method for multisize chokes. In this paper, the EGINA Oilfield, a deep-water faulted sandstone reservoir, located in West Africa was chosen as the research target. Based on Renard and Dupuy’s steady-state equation, the relationship between the productivity index per meter and the length of horizontal section was derived. Consequently, this relationship is used to determine the productivity pattern for long horizontal wells with the same geological features, which can provide more accurate productivity evaluations for tested wells and forecast the well productivity for untested wells. After implementing this approach on the EGINA Oilfield, the determined relationship is capable to accurately evaluate the test productivity for long horizontal wells in reservoirs with similar characteristics and assist in examination and treatment for horizontal wells with abnormal productivity.

Download Full-text

Fracture Parameters Optimization of BZ Oilfield Horizontal Well Integral Fracturing

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.457-458.692 ◽

2013 ◽

Vol 457-458 ◽

pp. 692-698

Author(s):

Wen Jiang Xu ◽

Yong Quan Hu ◽

Jin Zhou Zhao ◽

Zhi Qiang Li

Keyword(s):

Mathematical Model ◽

Optimization Design ◽

Horizontal Well ◽

Parameters Optimization ◽

Production Performance ◽

Oil Well ◽

Fracture Conductivity ◽

Fracture Length ◽

Fracture Parameters ◽

The Impact

Horizontal well technology has become an important technological means for offshore oilfield exploitation, but at present, most of the fracture parameters optimization of horizontal well fracturing are based on the single wells productivity after fracturing and pay less attention to consider the impact of injection wells.Therefore, aiming at injection and production development mode of BZ oilfield horizontal wells after fracturing, Integral fracturing physical model and productivity forecast mathematical model of horizontal well for the purpose of improving integrated exploitation benefit of the block is established respectively.Combining with reservoir parameters of BZ oilfield, a corresponding numerical simulator is developed by means of solving mathematical model to forecast production performance of oil well with different fracture number, fracture length, fracture conductivity. The best fracture parameters are obtained through analyzing the effect of fracture parameters on accumulative oil production, which provides theoretical foundation for integral fracturing optimization design of horizontal well of BZ oilfields, and has vital site guiding significance.

Download Full-text

Effect of Geological Heterogeneity on the Production Performance of a Multifractured Horizontal Well in Tight Gas Reservoirs

Lithosphere ◽

10.2113/2021/4336062 ◽

2021 ◽

Vol 2021 (Special 1) ◽

Author(s):

Yue Peng ◽

Tao Li ◽

Yuxue Zhang ◽

Yongjie Han ◽

Dan Wu ◽

...

Keyword(s):

Horizontal Well ◽

Horizontal Wells ◽

Gas Production ◽

Production Performance ◽

Tight Gas ◽

Gas Reservoirs ◽

Gas Reservoir ◽

Tight Gas Reservoirs ◽

Reservoir Permeability ◽

Half Length

Abstract Multifractured horizontal wells are widely used in the development of tight gas reservoirs to improve the gas production and the ultimate reservoir recovery. Based on the heterogeneity characteristics of the tight gas reservoir, the homogeneous scheme and four typical heterogeneous schemes were established to simulate the production of a multifractured horizontal well. The seepage characteristics and production performance of different schemes were compared and analyzed in detail by the analysis of streamline distribution, pressure distribution, and production data. In addition, the effects of reservoir permeability level, length of horizontal well, and fracture half-length on the gas reservoir recovery were discussed. Results show that the reservoir permeability of the unfractured areas, which are located at both ends of the multifractured horizontal well, determines the seepage ability of the reservoir matrix, showing a significant impact on the long-term gas production. High reservoir permeability level, long horizontal well length, and long fracture half-length can mitigate the negative influence of heterogeneity on the gas production. Our research can provide some guidance for the layout of multifractured horizontal wells and fracturing design in heterogeneous tight gas reservoirs.

Download Full-text

A Modeling Study of the Productivity of Horizontal Wells in Hydrocarbon-Bearing Reservoirs: Effects of Fracturing Interference

Geofluids ◽

10.1155/2021/2168622 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Lei Huang ◽

Peijia Jiang ◽

Xuyang Zhao ◽

Liang Yang ◽

Jiaying Lin ◽

...

Keyword(s):

Hydraulic Fracturing ◽

Horizontal Well ◽

Finite Difference Methods ◽

Horizontal Wells ◽

Fracture Initiation ◽

Design Parameters ◽

Porous Media Flow ◽

Propagation Mechanism ◽

Well Productivity ◽

Fracturing Process

Commercial production from hydrocarbon-bearing reservoirs with low permeability usually requires the use of horizontal well and hydraulic fracturing for the improvement of the fluid diffusivity in the matrix. The hydraulic fracturing process involves the injection of viscous fluid for fracture initiation and propagation, which alters the poroelastic behaviors in the formation and causes fracturing interference. Previous modeling studies usually focused on the effect of fracturing interference on the multicluster fracture geometry, while the related productivity of horizontal wells is not well studied. This study presents a modeling workflow that utilizes abundant field data including petrophysical, geomechanical, and hydraulic fracturing data. It is used for the quantification of fracturing interference and its correlation with horizontal well productivity. It involves finite element and finite difference methods in the numeralization of the fracture propagation mechanism and porous media flow problems. Planar multistage fractures and their resultant horizontal productivity are quantified through the modeling workflow. Results show that the smaller numbers of clusters per stage, closer stage spacings, and lower fracturing fluid injection rates facilitate even growth of fractures in clusters and stages and reduce fracturing interference. Fracturing modeling results are generally correlated with productivity modeling results, while scenarios with stronger fracturing interference and greater stimulation volume/area can still yield better productivity. This study establishes the quantitative correlation between fracturing interference and horizontal well productivity. It provides insights into the prediction of horizontal well productivity based on fracturing design parameters.

Download Full-text