Challenges of Gas Wells Killing Operation with Emphasis on Reservoir & Completion Integrity Issues

2021 ◽  
Author(s):  
Zeeshan Ahmad ◽  
Abdullah Alhaj Al Hosini ◽  
Mohammed Ibrahim Al Janahi ◽  
Abdulla Mohammed Al Marzouqi ◽  
Muhammad Ali SIDDIQUI ◽  
...  
Keyword(s):  
Gas Production ◽  
Fluid Loss ◽  
Gas Wells ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Advantages And Disadvantages ◽  
Reservoir Permeability ◽  
Production Wells ◽  
Zonal Isolation ◽  
Fluid Losses

Abstract Well killing always remains a most radical part during the life cycle of gas production wells with reservoir and completion integrity issues. In moderate permeability gas reservoirs, it will be more challenging due to below issues; Low pressure gas reservoir with moderate reservoir permeability where hydrostatic head of water is almost double the formation pressure Well with the sustainable annulus pressures (Production & first cemented annulus) Well with complex layered scale / asphalting deposition Completion jewelry component integrity breached Recycle reservoir with pressure maintenance Noise logs / corrosion logs generally conducted in order to assess the downhole completion jewelry and potential leak source prior any attempt for killing the well. To achieve the desired accessibility extensive scale analysis for better designing of scale clean out operation carried out specially to access the SPM. Variation of reservoir permeability considered for designing of optimized kill fluid for Depleted horizontal gas reservoir to cater challenge of complete losses. Effective fluid loss solutions designed and implemented to avoid abnormal fluid losses. Further more Polymer based gels used to kill and prevent the gas peculation to surface. Wells having completion and reservoir integrity issue isolated by considering cement zonal isolation, salt plugs, thru-tubing bridge plugs and nipple less plugs. All these barriers having their advantages and disadvantages with reference to work over objectives and their application limitations with respect to well conditions and detail study conducted for each candidate prior execution. Depletion Gas well killing and securing operation considered to be complex in nature and may result serious concern of rig intervention or well future objectives in case of improper execution. Gas wells having reservoir integrity issues and in case of 1st cemented Annulus pressure can be isolated by using thru-tubing bridge plugs. For retrieval of dummy from SPM must be done after setting of downhole plug to avoid any heavy suction for wire line operation. Cement plug operation is not suitable for such wells due to severe losses and fluid circulation limitation. Adequate selection of kill gel fluid as per reservoir characteristics will improve the killing efficiency.

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

Lithosphere ◽  
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.

Technology Focus: Unconventional and Tight Reservoirs (July 2021)

2021 ◽  
Vol 73 (07) ◽  
pp. 57-57
Author(s):  
Leonard Kalfayan
Keyword(s):  
Oil And Gas ◽  
Gas Production ◽  
Alternative Methods ◽  
Gas Wells ◽  
Gas Reservoirs ◽  
Liquid Loading ◽  
Well Production ◽  
Tight Carbonate ◽  
Water Blocking ◽  
Tight Reservoirs

As unconventional oil and gas fields mature, operators and service providers are looking toward, and collaborating on, creative and alternative methods for enhancing production from existing wells, especially in the absence of, or at least the reduction of, new well activity. While oil and gas price environments remain uncertain, recent price-improvement trends are supporting greater field testing and implementation of innovative applications, albeit with caution and with cost savings in mind. Not only is cost-effectiveness a requirement, but cost-reducing applications and solutions can be, too. Of particular interest are applications addressing challenging well-production needs such as reducing or eliminating liquid loading in gas wells; restimulating existing, underperforming wells, including as an alternative to new well drilling and completion; and remediating water blocking and condensate buildup, both of which can impair production from gas wells severely. The three papers featured this month represent a variety of applications relevant to these particular well-production needs. The first paper presents a technology and method for liquid removal to improve gas production and reserves recovery in unconventional, liquid-rich reservoirs using subsurface wet-gas compression. Liquid loading, a recurring issue downhole, can severely reduce gas production and be costly to remediate repeatedly, which can be required. This paper discusses the full technology application process and the supportive results of the first field trial conducted in an unconventional shale gas well. The second paper discusses the application of the fishbone stimulation system and technique in a tight carbonate oil-bearing formation. Fishbone stimulation has been around for several years now, but its best applications and potential have not necessarily been fully understood in the well-stimulation community. This paper summarizes a successful pilot application resulting in a multifold increase in oil-production rate and walks the reader through the details of the pilot candidate selection, completion design, operational challenges, and lessons learned. The third paper introduces and proposes a chemical treatment to alleviate phase trapping in tight carbonate gas reservoirs. Phase trapping can be in the form of water blocking or increasing condensate buildup from near the wellbore and extending deeper into the formation over time. Both can reduce relative permeability to gas severely. Water blocks can be a one-time occurrence from drilling, completion, workover, or stimulation operations and can often be treated effectively with solvent plus proper additive solutions. Similar treatments for condensate banking in gas wells, however, can provide only temporary alleviation, if they are even effective. This paper proposes a technique for longer-term remediation of phase trapping in tight carbonate gas reservoirs using a unique, slowly reactive fluid system. Recommended additional reading at OnePetro: www.onepetro.org. SPE 200345 - Insights Into Field Application of Enhanced-Oil-Recovery Techniques From Modeling of Tight Reservoirs With Complex High-Density Fracture Network by Geng Niu, CGG, et al. SPE 201413 - Diagnostic Fracture Injection Test Analysis and Simulation: A Utica Shale Field Study by Jeffery Hildebrand, The University of Texas at Austin, et al.

Non-Darcy Binomial Deliverability Equations for Partially Penetrating Vertical Gas Wells and Horizontal Gas Wells

2009 ◽  
Author(s):  
Tao Zhu ◽  
Jing Lu
Keyword(s):  
Bottom Water ◽  
Horizontal Wells ◽  
Vertical Wells ◽  
Gas Wells ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Well ◽  
Increase Productivity ◽  
Flow Domain ◽  
Inflow Performance

Many gas reservoirs are with bottom water drive. In order to prevent or delay unwanted water into the wellbore, the producing wells are often completed as partially penetrating vertical wells, and more and more horizontal wells have been drilled in recent years in bottom water drive gas reservoirs to reduce water coning and increase productivity. For a well, non-Darcy flow is inherently a near wellbore phenomenon. In spite of the considerable study that non-Darcy behavior of fully penetrating vertical wells, there has been no study of a partially penetrating vertical well or a horizontal well in a gas reservoir with bottom water drive. This paper presents new binomial deliverability equations for partially penetrating vertical gas wells and horizontal gas wells, assuming that only radial flow occurs in the near wellbore non-Darcy’s flow domain. The inflow performance of a vertical gas well is compared with that of a horizontal gas well. The proposed equations can account for the advantages of horizontal gas wells.

scholarly journals Analysis of the Influence of Different Fracture Network Structures on the Production of Shale Gas Reservoirs

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ming Yue ◽  
Xiaohe Huang ◽  
Fanmin He ◽  
Lianzhi Yang ◽  
Weiyao Zhu ◽  
...  
Keyword(s):  
Finite Element ◽  
Shale Gas ◽  
Flow Direction ◽  
Fracture Network ◽  
Gas Production ◽  
Low Flow ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Gas Seepage

Volume fracturing is a key technology in developing unconventional gas reservoirs that contain nano/micron pores. Different fracture structures exert significantly different effects on shale gas production, and a fracture structure can be learned only in a later part of detection. On the basis of a multiscale gas seepage model considering diffusion, slippage, and desorption effects, a three-dimensional finite element algorithm is developed. Two finite element models for different fracture structures for a shale gas reservoir in the Sichuan Basin are established and studied under the condition of equal fracture volumes. One is a tree-like fracture, and the other is a lattice-like fracture. Their effects on the production of a fracture network structure are studied. Numerical results show that under the same condition of equal volumes, the production of the tree-like fracture is higher than that of the lattice-like fracture in the early development period because the angle between fracture branches and the flow direction plays an important role in the seepage of shale gas. In the middle and later periods, owing to a low flow rate, the production of the two structures is nearly similar. Finally, the lattice-like fracture model is regarded as an example to analyze the factors of shale properties that influence shale gas production. The analysis shows that gas production increases along with the diffusion coefficient and matrix permeability. The increase in permeability leads to a larger increase in production, but the decrease in permeability leads to a smaller decrease in production, indicating that the contribution of shale gas production is mainly fracture. The findings of this study can help better understand the influence of different shapes of fractures on the production in a shale gas reservoir.

Well Completion for Effective Deliquification of Natural Gas Wells

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
John Yilin Wang
Keyword(s):  
Natural Gas ◽  
Operating Cost ◽  
Gas Production ◽  
Gas Wells ◽  
Liquid Loading ◽  
Gas Recovery ◽  
Well Completion ◽  
Reservoir Permeability ◽  
Gas Fields ◽  
Gas Lift

Liquid loading has been a problem in natural gas wells for several decades. With gas fields becoming mature and gas production rates dropping below the critical rate, deliquification becomes more and more critical for continuous productivity and profitability of gas wells. Current methods for solving liquid loading in the wellbore include plunger lift, velocity string, surfactant, foam, well cycling, pumps, compression, swabbing, and gas lift. All these methods are to optimize the lifting of liquid up to surface, which increases the operating cost, onshore, and offshore. However, the near-wellbore liquid loading is critical but not well understood. Through numerical reservoir simulation studies, effect of liquid loading on gas productivity and recovery has been quantified in two aspects: backup pressure and near-wellbore liquid blocking by considering variable reservoir permeability, reservoir pressure, formation thickness, liquid production rate, and geology. Based on the new knowledge, we have developed well completion methods for effective deliquifications. These lead to better field operations and increased ultimate gas recovery.

Analysis of Fractured Sections in Shale Gas Wells Based on PCA - Logistic Regression Model

2020 ◽  
Vol 980 ◽  
pp. 483-492
Author(s):  
Lei Ji ◽  
Ju Hua Li ◽  
Guan Qun Li ◽  
Jia Lin Xiao ◽  
Sean Unrau
Keyword(s):  
Logistic Regression ◽  
Shale Gas ◽  
Logistic Regression Model ◽  
Gas Production ◽  
Gas Wells ◽  
Gas Reservoirs ◽  
Discriminant Model ◽  
Economic Exploitation ◽  
High Production ◽  
Pca Algorithm

In order to optimize the layout and economic exploitation of horizontal fracturing wells and completion in shale gas reservoirs, we propose a model for evaluating shale gas fractured sections based on an improved principle component analysis (PCA) algorithm with logistic regression. The 229 gas production sections in 22 fractured shale gas wells in the main block of the Fuling Shale Development Demonstration Zone were selected, and PCA is used for dimensionalite reduction. According to the PCA results, 6 key parameters are chosen to determine the productivity of fractured wells. Taking the probability distribution of high production after fracturing as the research objective, a logistic regression discriminant model was constructed using the dichotomy method. The prediction results show that the model has 82.1% accuracy and is reliable. The model can be used to classify and gas wells to be fractured, and it provides guiding significance for reasonable optimization of well sections in the area selected for fracturing.

Identification Method for Shallow Gas Layers in Cased Well

2014 ◽  
Vol 508 ◽  
pp. 146-149
Author(s):  
Xiao Min Tang ◽  
Xin Deng ◽  
Jian Fu ◽  
Lin Hou
Keyword(s):  
Gas Production ◽  
Production Testing ◽  
Neutron Lifetime ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Shallow Gas ◽  
Identification Methods ◽  
Identification Method ◽  
Gas Formation

In this paper, based on log response in gas formation, effective identification curves for shallow gas reservoirs are preferred from casedhole compensated neutron log, neutron lifetime log and openhole logs, and 4 parameters and 5 overlap curves are developed for identification of shallow gas reservoirs in cased wells. A gas reservoir in cased wells is interpreted with proposed identification methods. The gas production testing results shows that the proposed methods can determine shallow gas reservoirs in cased wells accurately.

scholarly journals ANALYSIS OF THE DYNAMICS OF RESERVOIR WATER INTRODUCTION IN THE GAS RESERVOIR ON THE DECLINE OF GAS PRODUCTION

2019 ◽  
pp. 41-44
Author(s):  
I. I. Baydin ◽  
A. V. Kovalenko ◽  
N. V. Gumerova ◽  
An. V. Kovalenko
Keyword(s):  
Western Siberia ◽  
Gas Production ◽  
Observation Well ◽  
Gas Reservoir ◽  
Reservoir Water ◽  
Production Wells ◽  
History Of ◽  
Technological Model

The article analyzes the reservoir behavior on the decline of falling production and field stops, shows the indicators of well bushes at one of the fields in Western Siberia, including four production wells and one observation well. The calculations have been performed on a threedimensional geological and technological model, which is adapted to the history of the deposit development taking into account its ground infrastructure.

scholarly journals Hydrodynamic Equilibrium Simulation and Shut-in Time Optimization for Hydraulically Fractured Shale Gas Wells

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 961
Author(s):  
Fei Wang ◽  
Qiaoyun Chen ◽  
Yingqi Ruan
Keyword(s):  
Shale Gas ◽  
Gas Production ◽  
Fluid Loss ◽  
Hydraulic Fractures ◽  
Hydraulic Pressure ◽  
Gas Wells ◽  
Fracturing Fluid ◽  
Equilibrium Time ◽  
Chemical Osmosis ◽  
Hydrodynamic Equilibrium

Post-fracturing well shut-in is traditionally due to the elastic closure of hydraulic fractures and proppant compaction. However, for shale gas wells, the extension of shut-in time may improve the post-fracturing gas production due to formation energy supplements by fracturing-fluid imbibition. This paper presents a methodology using numerical simulation to simulate the hydrodynamic equilibrium phenomenon of a hydraulically fractured shale gas reservoir, including matrix imbibition and fracture network crossflow, and further optimize the post-fracturing shut-in time. A mathematical model, which can describe the fracturing-fluid hydrodynamic transport during the shut-in process, and consider the distinguishing imbibition characteristics of a hydraulically fractured shale reservoir, i.e., hydraulic pressure, capillarity and chemical osmosis, is developed. The key concept, i.e., hydrodynamic equilibrium time, for optimizing the post-fracturing shut-in schedule, is proposed. The fracturing-fluid crossflow and imbibition profiles are simulated, which indicate the water discharging and sucking equilibrium process in the coupled fracture–matrix system. Based on the simulation, the hydrodynamic equilibrium time is calculated. The influences of hydraulic pressure difference, capillarity and chemical osmosis on imbibition volume, and hydrodynamic equilibrium time are also investigated. Finally, the optimal shut-in time is determined if the gas production rate is pursued and the fracturing-fluid loss is allowable. The proposed simulation method for determining the optimal shut-in time is meaningful to the post-fracturing shut-in schedule.

scholarly journals The Researches on Reasonable Well Spacing of Gas Wells in Deep and low Permeability Gas Reservoirs

2018 ◽  
Vol 38 ◽  
pp. 01038
Author(s):  
Yu Bei Bei ◽  
Li Hui ◽  
Li Dong Lin
Keyword(s):  
Pressure Gradient ◽  
Low Permeability ◽  
Well Testing ◽  
Gas Wells ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Field ◽  
Well Spacing ◽  
Start Up ◽  
Starting Pressure Gradient

This Gs64 gas reservoir is a condensate gas reservoir which is relatively integrated with low porosity and low permeability found in Dagang Oilfield in recent years. The condensate content is as high as 610g/m3. At present, there are few reports about the well spacing of similar gas reservoirs at home and abroad. Therefore, determining the reasonable well spacing of the gas reservoir is important for ensuring the optimal development effect and economic benefit of the gas field development. This paper discusses the reasonable well spacing of the deep and low permeability gas reservoir from the aspects of percolation mechanics, gas reservoir engineering and numerical simulation. considering there exist the start-up pressure gradient in percolation process of low permeability gas reservoir, this paper combined with productivity equation under starting pressure gradient, established the formula of gas well spacing with the formation pressure and start-up pressure gradient. The calculation formula of starting pressure gradient and well spacing of gas wells. Adopting various methods to calculate values of gas reservoir spacing are close to well testing' radius, so the calculation method is reliable, which is very important for the determination of reasonable well spacing in low permeability gas reservoirs.

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