scholarly journals Secondary formation damage of low-pressure layer during commingled production in multilayered tight gas reservoirs

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jingchen Ding ◽  
Changhui Yan ◽  
Yongming He ◽  
Changcheng Wang
Keyword(s):  
Water Saturation ◽  
Low Pressure ◽  
Working Fluid ◽  
Formation Damage ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Back Flow ◽  
Tight Gas Reservoirs ◽  
Secondary Formation ◽  
Tight Gas Reservoir

AbstractThis paper experimentally investigates fluid back-flow behavior and formation damage during commingled production in multilayered tight gas reservoirs. The development of fluid back-flow in commingled tight gas reservoirs was simulated using a newly designed experimental platform. The results indicate that when there is a pressure difference between different layers during commingled production from tight gas reservoir, water produced from the high-pressure layer will invade the low-pressure layer along with gas back-flow and will accumulate in the near-wellbore area. This will lead to an increase in water saturation and a decline in permeability in the low-pressure layer and result in a significant reduction in ultimate recovery. The outcomes of these experiments demonstrate that as well as the formation damage caused by the working fluid during drilling and fracturing, “Secondary Formation Damage” also occurs during commingled production in multilayered tight gas reservoirs. This secondary formation damage mainly occurs in the near-wellbore area of low-pressure layers and is more severe with greater proximity to the wellbore. Through further experimentation to assess the factors influencing secondary formation damage, it is shown that the degree of secondary formation damage increases with decreasing original formation pressure, original water saturation, and permeability in the lower-pressure layer.

scholarly journals A new model for predicting irreducible water saturation in tight gas reservoirs

2020 ◽  
Vol 17 (4) ◽  
pp. 1087-1100
Author(s):  
Yu-Liang Su ◽  
Jin-Gang Fu ◽  
Lei Li ◽  
Wen-Dong Wang ◽  
Atif Zafar ◽  
...  
Keyword(s):  
Water Saturation ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
New Model ◽  
Irreducible Water Saturation

Lowering the phase-trap damage in tight-gas reservoirs by using interfacial tension (IFT) reducers

2013 ◽  
Vol 53 (1) ◽  
pp. 363
Author(s):  
Yangfan Lu ◽  
Hassan Bahrami ◽  
Mofazzal Hossain ◽  
Ahmad Jamili ◽  
Arshad Ahmed ◽  
...  
Keyword(s):  
Relative Permeability ◽  
Reservoir Simulation ◽  
Water Saturation ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Water Based ◽  
Tight Formations ◽  
Tight Reservoirs ◽  
Relative Permeability Curves

Tight-gas reservoirs have low permeability and significant damage. When drilling the tight formations, wellbore liquid invades the formation and increases water saturation of the near wellbore area and significantly deceases permeability of this area. Because of the invasion, the permeability of the invasion zone near the wellbore in tight-gas formations significantly decreases. This damage is mainly controlled by wettability and capillary pressure (Pc). One of the methods to improve productivity of tight-gas reservoirs is to reduce IFT between formation gas and invaded water to remove phase trapping. The invasion of wellbore liquid into tight formations can damage permeability controlled by Pc and relative permeability curves. In the case of drilling by using a water-based mud, tight formations are sensitive to the invasion damage due to the high-critical water saturation and capillary pressures. Reducing the Pc is an effective way to increase the well productivity. Using the IFT reducers, Pc effect is reduced and trapped phase can be recovered; therefore, productivity of the TGS reservoirs can be increased significantly. This study focuses on reducing phase-trapping damage in tight reservoirs by using reservoir simulation to examine the methods, such use of IFT reducers in water-based-drilled tight formations that can reduce Pc effect. The Pc and relative permeability curves are corrected based on the reduced IFT; they are then input to the reservoir simulation model to quantitatively understand how IFT reducers can help improve productivity of tight reservoirs.

Fracturing in Tight-Gas Reservoirs: Application of SCAL Methods To Investigate Formation-Damage Mechanisms

2008 ◽  
Author(s):  
Brigitte Bazin ◽  
Samir Bekri ◽  
Olga Vizika ◽  
Benjamin Herzhaft ◽  
Eric Aubry
Keyword(s):  
Formation Damage ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Damage Mechanisms ◽  
Tight Gas Reservoirs

Experimental quantification of formation damage caused by the cross-linked gel in tight gas reservoirs

2020 ◽  
Vol 84 ◽  
pp. 103608 ◽  
Author(s):  
Xingyuan Liang ◽  
Fujian Zhou ◽  
Tianbo Liang ◽  
Caizhong Wang ◽  
Yuan Li
Keyword(s):  
Formation Damage ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
The Cross

Liquid loading in wellbores and its effect on cleanup period and well productivity in tight gas sand reservoirs

2010 ◽  
Vol 50 (1) ◽  
pp. 559
Author(s):  
Hassan Bahrami ◽  
M Reza Rezaee ◽  
Vamegh Rasouli ◽  
Armin Hosseinian
Keyword(s):  
Numerical Simulation ◽  
Gas Production ◽  
Production Performance ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Liquid Loading ◽  
Performance Modelling ◽  
Well Productivity ◽  
Tight Gas Reservoirs ◽  
Tight Gas Reservoir

Tight gas reservoirs normally have production problems due to very low matrix permeability and significant damage during well drilling, completion, stimulation and production. Therefore they might not flow gas to surface at optimum rates without advanced production improvement techniques. After well stimulation and fracturing operations, invaded liquids such as filtrate will flow from the reservoir into the wellbore, as gas is produced during well cleanup. In addition, there might be production of condensate with gas. The produced liquids when loaded and re-circulated downhole in wellbores, can significantly reduce the gas production rate and well productivity in tight gas formations. This paper presents assessments of tight gas reservoir productivity issues related to liquid loading in wellbores using numerical simulation of multiphase flow in deviated and horizontal wells. A field example of production logging in a horizontal well is used to verify reliability of the numerical simulation model outputs. Well production performance modelling is also performed to quantitatively evaluate water loading in a typical tight gas well, and test the water unloading techniques that can improve the well productivity. The results indicate the effect of downhole liquid loading on well productivity in tight gas reservoirs. It also shows how well cleanup is sped up with the improved well productivity when downhole circulating liquids are lifted using the proposed methods.

Induced and natural fracture interaction in tight-gas reservoirs

2012 ◽  
Vol 52 (1) ◽  
pp. 611
Author(s):  
Mohammad Rahman ◽  
Sheik Rahman
Keyword(s):  
Hydraulic Fracture ◽  
Development Planning ◽  
Natural Fracture ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Differential Stress ◽  
Tight Gas Reservoirs ◽  
Reservoir Development ◽  
Well Spacing ◽  
Tight Gas Reservoir

This paper investigates the interaction of an induced hydraulic fracture in the presence of a natural fracture and the subsequent propagation of this induced fracture. The developed, fully coupled finite element model integrates a wellbore, an induced hydraulic fracture, a natural fracture, and a reservoir that simulates interaction between the induced and natural fracture. The results of this study have shown that natural fractures can have a profound effect on induced fracture propagation. In most cases, the induced fracture crosses the natural fracture at high angles of approach and high differential stress. At low angles of approach and low differential stress, the induced fracture is more likely to be arrested and/or break out from the far-end side of the natural fracture. It has also been observed that the propagation of the induced fracture is stopped by a large natural fracture at a high angle of approach, when the injection rate remains low. At a low angle of approach, the induced fracture deviates and propagates along the natural fracture. Crossing of the natural fracture and/or arrest by the natural fracture is controlled by the shear strength of the natural fracture, natural fracture orientation, and the in situ stress state of the reservoir. In tight-gas reservoir development, the optimum well spacing and induced hydraulic fracture length are correlated. Therefore, fracturing design should be performed during the initial reservoir development planning phase along with the well spacing design to obtain an optimal depletion strategy. This model has a potential application in the design and optimisation of fracturing design in unconventional reservoirs including tight-gas reservoirs and enhanced geothermal systems.

scholarly journals Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Renyi Cao ◽  
Liyou Ye ◽  
Qihong Lei ◽  
Xinhua Chen ◽  
Y. Zee Ma ◽  
...  
Keyword(s):  
Water Saturation ◽  
Flow Behavior ◽  
Stress Sensitivity ◽  
Gas Production ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Threshold Pressure Gradient ◽  
Tight Gas Reservoirs ◽  
Gas Recovery ◽  
Mobile Water

Some tight sandstone gas reservoirs contain mobile water, and the mobile water generally has a significant impact on the gas flowing in tight pores. The flow behavior of gas and water in tight pores is different than in conventional formations, yet there is a lack of adequate models to predict the gas production and describe the gas-water flow behaviors in water-bearing tight gas reservoirs. Based on the experimental results, this paper presents mathematical models to describe flow behaviors of gas and water in tight gas formations; the threshold pressure gradient, stress sensitivity, and relative permeability are all considered in our models. A numerical simulator using these models has been developed to improve the flow simulation accuracy for water-bearing tight gas reservoirs. The results show that the effect of stress sensitivity becomes larger as water saturation increases, leading to a fast decline of gas production; in addition, the nonlinear flow of gas phase is aggravated with the increase of water saturation and the decrease of permeability. The gas recovery decreases when the threshold pressure gradient (TPG) and stress sensitivity are taken into account. Therefore, a reasonable drawdown pressure should be set to minimize the damage of nonlinear factors to gas recovery.

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