scholarly journals Shale Gas Productivity Predicting Model and Analysis of Influence Factors

2015 ◽  
Vol 8 (1) ◽  
pp. 203-207 ◽  
Author(s):  
Yin Daiyin ◽  
Wang Dongqi ◽  
Zhang Chengli ◽  
Duan Yingjiao
Keyword(s):  
Mathematical Model ◽  
Pressure Gradient ◽  
Shale Gas ◽  
Diffusion Mechanism ◽  
Influence Factors ◽  
Mass Conservation ◽  
Isothermal Adsorption ◽  
Start Up ◽  
Gas Seepage ◽  
The Impact

In order to find the dynamic characteristics of shale gas reservoirs and improve shale gas well production, it is very important to research on shale gas seepage mechanism and production evaluation. Based on the shale gas seepage mechanism, adsorption and desorption characteristics, the diffusion mechanism and mass conservation theory in shale gas development, the dual pore medium shale gas reservoir mathematical model is set up. The mathematical model is built by the finite difference method based on start-up pressure gradient, slippage effect and the isothermal adsorption principle, and then programmed to solve it. Finally, this paper analyzed the impact of Langmuir volume, Langmuir pressure, start-up pressure gradient and slippage coefficient and other factors on shale gas wells production.

scholarly journals Productivity Influence Factors of Tight Sandstone Gas Reservoir with Water Produced

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yongchao Xue ◽  
Qingshuang Jin ◽  
Hua Tian
Keyword(s):  
Pressure Gradient ◽  
Relative Permeability ◽  
Gas Flow ◽  
Influence Factors ◽  
Stress Sensitivity ◽  
Consumption Pattern ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Two Phase ◽  
Start Up

Finding ways to accelerate the effective development of tight sandstone gas reservoirs holds great strategic importance in regard to the improvement of consumption pattern of world energy. The pores and throats of the tight sandstone gas reservoir are small with abundant interstitial materials. Moreover, the mechanism of gas flow is highly complex. This paper is based on the research of a typical tight sandstone gas reservoir in Changqing Oilfield. A strong stress sensitivity in tight sandstone gas reservoir is indicated by the results, and it would be strengthened with the water production; at the same time, a rise to start-up pressure gradient would be given by the water producing process. With the increase in driving pressure gradient, the relative permeability of water also increases gradually, while that of gas decreases instead. Following these results, a model of gas-water two-phase flow has been built, keeping stress sensitivity, start-up pressure gradient, and the change of relative permeability in consideration. It is illustrated by the results of calculations that there is a reduction in the duration of plateau production period and the gas recovery factor during this period if the stress sensitivity and start-up pressure gradient are considered. In contrast to the start-up pressure gradient, stress sensitivity holds a greater influence on gas well productivity.

scholarly journals Numerical Simulation of Shale Gas Multiscale Seepage Mechanism-Coupled Stress Sensitivity

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Xun Yan ◽  
Jing Sun ◽  
Dehua Liu
Keyword(s):  
Shale Gas ◽  
Gas Flow ◽  
Gas Transport ◽  
Sensitivity Coefficient ◽  
Stress Sensitivity ◽  
Gas Production ◽  
Molecular Flow ◽  
Adsorption Phenomenon ◽  
Gas Seepage ◽  
The Impact

The complexity of the gas transport mechanism in microfractures and nanopores is caused by the feature of multiscale and multiphysics. Figuring out the flow mechanism is of great significance for the efficient development of shale gas. In this paper, an apparent permeability model which covers continue, slip, transition, and molecular flow and geomechanical effect was presented. Additionally, a mathematical model comprising multiscale, geomechanics, and adsorption phenomenon was proposed to characterize gas flow in the shale reservoir. The aim of this paper is to investigate some important impacts in the process of gas transportation, which includes the shale stress sensitivity, adsorption phenomenon, and reservoir porosity. The results reveal that the performance of the multistage fractured horizontal well is strongly influenced by stress sensitivity coefficient. The cumulative gas production will decrease sharply when the shale gas reservoir stress sensitivity coefficient increases. In addition, the adsorption phenomenon has an influence on shale gas seepage and sorption capacity; however, the effect of adsorption is very weak in the early gas transport period, and the impact of later will increase. Moreover, shale porosity also greatly affects the shale gas transportation.

Field Testing of the Flowback Technology for Multistage-Fractured Horizontal Wells: Generalization to Find an Optimum Balance Between Aggressive and Smooth Scenarios

2021 ◽  
Author(s):  
Albert Vainshtein ◽  
Georgii Fisher ◽  
Gleb Strizhnev ◽  
Sergei Boronin ◽  
Andrei Osiptsov ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Hydraulic Fracture ◽  
Fracture Length ◽  
Well Production ◽  
Drop Dynamics ◽  
Start Up ◽  
Cumulative Production ◽  
Fluid Rheology ◽  
The Impact

Abstract We present the results of field experiments campaign on start-up of wells located in a sandstone oilfield of Western Siberia and history matching of coupled "wellbore-hydraulic fracture" model describing well start-up and fracture clean-up. The conclusion is made about the impact of rheological and geomechanical factors on the well cumulative production andfracture conductivity.The results are generalized for four wells of the field experiment and 30 wells of the retrospective analysis. Calculations of well startup are carried out using standalone fracture cleanup model and the coupled model, which includes models for filtration inside closed hydraulic fracture and flow in the wellbore. The data obtained during field tests on well startup is used to history match the fracture clean-up model. The adaptation allows to evaluate the sensitivity of well production to various physical parameters and find the safe operating envelope of operational parameters during well startup. Numerical simulations allow take into account geomechanics effectsand rheology properties of fracturing fluid, study the dynamics of effective (cleaned) fracture length as well as evaluate the influence of pressure drop dynamics on filtration properties of the fracture and cumulative well production. We extended the number of wells to study the impact of flowback scenarios on production andgeneralized the results of our previous study.Key parameters affecting the history match process of the mathematical model are determined,the uncertainty associated with fluid rheology is reduced. Using the history-matched model, we evaluated geomechanics effects on fracture degradation depending on bottom-hole pressure drop dynamics. Based on the obtained dynamics of dimensionless parameters, such as pressure and fracture productivity, we propose an optimized well start-up strategy aimed at maximizing effective fracture length and cumulative production. Additionally, we visualized the dynamics of fracture conductivity distribution along its length. The obtained results are consistent with interpretation of physical processes accompanying well start-up and fracture clean-up. Dimensionless productivity index is chosen to quantify the effects of geomechanics and fluid rheology on well production.On the basis of matched mathematical model, we predict a potential increase in production of the well with optimized start-up.The recommendations are presented in the form of the dynamics of wellhead choke opening and a sequence of choke diameters. We propose an integrated approach for planning a well flowback strategy after multi-stage hydraulic fracturing. The proposed decision-making algorithm considers the effects of geomechanics and yield-stress hydraulic fracturing fluid rheology on cumulative production. It allows to develop a design for the well start-up and fracture cleanup in terms of dynamics of wellheadchoke opening.

Shale Gas Seepage Mechanism and Pressure Dynamic Characteristics Research

2013 ◽  
Vol 652-654 ◽  
pp. 2484-2489
Author(s):  
Yong Ming Li ◽  
Ya Zhou Li ◽  
Xue Ping Zhang ◽  
Jin Zhou Zhao ◽  
Lie Hui Zhang
Keyword(s):  
Mathematical Model ◽  
Shale Gas ◽  
Economic Benefits ◽  
Processing Method ◽  
Numerical Inversion ◽  
Fracture System ◽  
Response Curves ◽  
Flow Process ◽  
Gas Seepage ◽  
The Mathematical Model

The shale gas reserves could bring huge economic benefits. Therefore, many domestic and international scholars had researched it in all aspects. The research of seepage mechanism is mostly based on double seepage medium, they think gas spread directly into the fracture system when gas instantaneous desorbing from adsorption medium surface. However, the processing method is not very appropriate, because a certain amount of free gas present in rock matrixes pores. In order to describe the flow process accurately, this paper proposed a new concept of triple porous media, established a new model of shale gas seepage and solved the mathematical model by using Laplace transform and Stehfest numerical inversion. Finally figured out pressure dynamic response curves and analyzed the influence of all parameters on these curves.

scholarly journals Influencing Factors and Mathematical Prediction of Shale Adsorbed Gas Content in the Upper Triassic Yanchang Formation in the Ordos Basin, China

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 265 ◽  
Author(s):  
Ling Tang ◽  
Yan Song ◽  
Zhenxue Jiang ◽  
Xiongqi Pang ◽  
Zhuo Li ◽  
...  
Keyword(s):  
Shale Gas ◽  
Influence Factors ◽  
Economic Benefits ◽  
Gas Content ◽  
Analysis Method ◽  
Isothermal Adsorption ◽  
Resource Potential ◽  
Yanchang Formation ◽  
Geological Factors ◽  
Factor Regression

Evaluating absorbed gas content (AGC) in shales is crucial for accurately characterizing shale gas reservoirs and calculating resource potential. To investigate geological factors influencing AGC, 15 shale samples collected from the Yanchang Formation underwent related experiments. Then geochemistry features, mineral compositions, pore structure parameters and external factors were analyzed. The actual AGC was calculated using the Langmuir equation. Single geological factors acting on the AGC were discussed by the single-factor correlation analysis. Finally, four main influence factors (total organic carbon, S1, quartz content and formation temperature) were selected out from the 12 influence factors to establish the mathematical prediction model through the multi-factor regression statistical analysis method using SPSS software. The model was verified as being reliable with R2 as high as 0.8046 and relative error less than ±20%. Comparisons show that both the CH4 isothermal adsorption experimental method and the multi-factor regression analysis method have their own applicability and disadvantages, and they can complement each other in evaluating AGC in shales. Synthetic evaluation of AGC indicates that the Yanchang shale has an overall moderate AGC occupying about 58% of the total, which is helpful to extend shale gas production time of the Yanchang reservoir. Though under the present conditions, economic benefits of the continental shale gas are not obvious, the shale resource potential of Yanchang formation can’t be ignored.

MATHEMATICAL MODEL FOR ISOTHERMAL ADSORPTION OF SUPERCRITICAL SHALE GAS

2019 ◽  
Vol 22 (4) ◽  
pp. 499-510
Author(s):  
Zuping Xiang ◽  
Hongbin Liang ◽  
Zhilin Qi ◽  
Qianhua Xiao ◽  
Wende Yan ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Shale Gas ◽  
Isothermal Adsorption

Impacts of the Split Conjugated Pistons in Conjugated Cylinders of a Multiple Stage Reciprocating Compressor in Start Duration

1999 ◽  
Author(s):  
Jianqiang Deng ◽  
Zhaolin Gu ◽  
Yongzhang Yu
Keyword(s):  
Mathematical Model ◽  
High Pressure ◽  
Material Selection ◽  
Threshold Value ◽  
Discharge System ◽  
Pressure Stage ◽  
Multi Stage ◽  
Start Up ◽  
High Pressure Stage ◽  
The Impact

Abstract Split pistons allow more precise manufacturing and easier assembly of conjugate-piston multi-stage reciprocating compressors. Their disadvantage is that during start up, the high pressure stage piston may impact with both its cylinder head and the low-pressure stage piston. To determine the magnitude of these impacts and how they can be minimized, a simple mathematical model was constructed to analyze the pressure build-up within the compressor and the movement of the high-pressure stage piston. It is shown that above a minimum threshold value of pressure in the high-pressure stage, the pistons remain attached and move together without impact. The calculation of this minimum pressure along with the contact stresses, during rounds of impacts when the forces are greatest is demonstrated. A mathematical model is also provided to help minimize the impact stresses involved in such an arrangement. It is shown that by appropriate piston design and choice of piston material, selection of the optimum stroke and volume of the discharge system as well as the electric motor, split-conjugate pistons can be used in high-pressure multi-stage compressors.

Leakage Simulation of the Impactor of Hydraulic Rock Drill

2013 ◽  
Vol 744 ◽  
pp. 113-117
Author(s):  
Zhong Jun Yin ◽  
Guang Tian Xia ◽  
Tian Han
Keyword(s):  
Mathematical Model ◽  
Simulation Analysis ◽  
Influence Factors ◽  
Dynamics Simulation ◽  
Effective Control ◽  
Impact Mechanism ◽  
Rock Drill ◽  
Leakage Mechanism ◽  
The Impact ◽  
The Mathematical Model

In order to research the leakage mechanism and influence factors of the hydraulic rock drill, the mathematical model of the leakage is established, and combined with the structure and working principle of the hydraulic rock drill, the impact mechanism dynamics simulation model is built by the AMESim software. Through the analysis of the leakage model, the influence of differential pressure, sealing length and clearance on the leakage is got, the simulation analysis results are consistent with the mathematical model conclusions, and the results have important guiding significance on the clearance selection and the effective control of leakage of the impact mechanism.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

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