scholarly journals Experimental Study on the Effective Utilization of Reserves in Tight Sandstone Gas Reservoirs and Their Applications

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jie Zhang ◽  
Feifei Fang ◽  
Weijun Shen ◽  
Huaxun Liu ◽  
Shusheng Gao ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Moving Boundary ◽  
Production Performance ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Effective Utilization ◽  
Tight Gas Reservoir ◽  
Water Cut ◽  
Field Production

The effective utilization of reserves in tight sandstone reservoirs is one of the major concerns in terms of the development of tight sandstone gas reservoirs. However, the characteristics of reserve utilization are not fully understood, and many uncertainties still exist in the process. For this purpose, long cores on the Su 6 block of Sulige tight sandstone gas field in China were selected, and a multipoint embedded measurement system was established to study the characteristics of effective reserve utilization. Then, the effects of the related reservoir properties and production parameters were investigated. Based on the similarity theory, the effective conversion relationship between the physical experiment and the actual field production was established. The results showed that the pressure distribution in the exploitation of tight gas reservoir is nonlinear, and water cut in the reservoir will hinder the effective utilization of reserves. The lower the reservoir permeability, the larger the negative effect of water on reservoir utilization. Lower gas production rate and higher original pressure are associated with a smoother drawdown curve, which results in larger reserve utilization. The moving boundary expands with time, and its initial propagation velocity increase and then decrease. Additionally, the water cut in the reservoir can delay the spread of moving boundary propagation. The experimental results are consistent with the actual results of the field production by the similarity criterion, which can reflect and predict the production performance in tight gas reservoirs effectively. These results can provide a better understanding of reservoir pressure distribution and effective utilization of reserves to optimize the gas recovery and development benefit in tight sandstone gas reservoirs.

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.

scholarly journals Threshold Pore Pressure Gradients in Water-Bearing Tight Sandstone Gas Reservoirs

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4578
Author(s):  
Yong Wang ◽  
Yunqian Long ◽  
Yeheng Sun ◽  
Shiming Zhang ◽  
Fuquan Song ◽  
...  
Keyword(s):  
Water Saturation ◽  
High Water ◽  
Linear Regression Method ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Gas Seepage ◽  
Tight Gas Reservoir ◽  
Core Permeability

Tight gas reservoirs commonly occur in clastic formations having a complex pore structure and a high water saturation, which results in a threshold pressure gradient (TPG) for gas seepage. The micropore characteristics of a tight sandstone gas reservoir (Tuha oilfield, Xinjiang, China) were studied, based on X-ray diffraction, scanning electron microscopy and high pressure mercury testing. The TPG of gas in cores of the tight gas reservoir was investigated under various water saturation conditions, paying special attention to core permeability and water saturation impact on the TPG. A mathematical TPG model applied a multiple linear regression method to evaluate the influence of core permeability and water saturation. The results show that the tight sandstone gas reservoir has a high content of clay minerals, and especially a large proportion of illite–smectite mixed layers. The pore diameter is distributed below 1 micron, comprising mesopores and micropores. With a decrease of reservoir permeability, the number of micropores increases sharply. Saturated water tight cores show an obvious non-linear seepage characteristic, and the TPG of gas increases with a decrease of core permeability or an increase of water saturation. The TPG model has a high prediction accuracy and shows that permeability has a greater impact on TPG at high water saturation, while water saturation has a greater impact on TPG at low permeability.

3D Modeling of Hydraulic Fracturing in Tight Gas Reservoirs by Using of FLAC3D and Validation through Comparison with FracPro

2012 ◽  
Vol 524-527 ◽  
pp. 1293-1299 ◽  
Author(s):  
Lei Zhou ◽  
Jian Chun Guo
Keyword(s):  
Moving Boundary ◽  
Fracture Propagation ◽  
Scale Model ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Gas Reservoir ◽  
Moving Boundary Condition ◽  
North Germany ◽  
Stress States ◽  
Rock Mechanical Properties

In this paper, the FDM-Program FLAC3D is used for the 3D simulation of fracture propagation on a field scale model, based on field data of a Rotliegend tight gas reservoir in North Germany. This reservoir was treated hydraulically by a massive fracturing. The results regarding the fracture propagation were compared with those in the semi-analytical P3D simulator FracPro. It was noticed that the original code FLAC3D was unsuitable for the applications of hydraulic fracture. In further investigations, our own developed algorithm with a moving boundary condition based on discontinuum mechanics was implemented in FLAC3D. The results showed a relatively good agreement with those of FracPro. The advantage of the new algorithm is above all that irregular fracture front can be realistically simulated, which in turn reflects the stress states in multi-layers and their different rock mechanical properties

Optimization of Fracture Spacing in Western Sichuan Tight Gas Based on Fracture Interference

2014 ◽  
Vol 971-973 ◽  
pp. 2115-2119
Author(s):  
Bo Luo ◽  
Jian Chun Guo ◽  
Cong Lu
Keyword(s):  
Net Present Value ◽  
Production Performance ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Fracture Spacing ◽  
Western Sichuan ◽  
Sand Body ◽  
Tight Gas Reservoir ◽  
Result Show

Western Sichuan Depression is a typical tight gas reservoir, the effective stimulation methods for such reservoir is staged fracturing in horizontal wells. But, scholars failed to give the method to set reasonable fracture spacing in tight gas. In this paper, Western Sichuan tight gas reservoir continuous sand body model is established by numerical simulation, through which the gas reservoir production performance in different facture spacing can be learned. Numerical pressure in the vicinity of fracture to describe the scale of fracture interference by the law of pressure drop super position. Then, net present value is used to optimize fracture spacing. The result show that 73 m is the optimal fracture spacing of II B continuous sand body in XinMa blcok .The research method is not only applicable to continuous sand body of tight gas reservoirs, but can be extended to non-continuous sand body. Furthermore it plays a constructive role in promoting the fracturing exploitation in tight gas.

scholarly journals Study on Rheological Properties of Nanofluids

2021 ◽  
Vol 2132 (1) ◽  
pp. 012049
Author(s):  
Yan-qing Bian ◽  
Pu-cheng Wu ◽  
Jing Hao ◽  
Quan Shi ◽  
Guo-wei Qin
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Oil And Gas ◽  
Loss Modulus ◽  
Production Capacity ◽  
Tight Gas ◽  
Water Control ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Tight Gas Reservoir

Abstract Based on the previous research on the rheological properties of nanofluids by many scholars at home and abroad, to solve the problem that the viscosity of conventional polymer water control agents is large and cannot meet the demand for increasing production capacity in the process of tight gas reservoir exploitation, this paper takes self-made nanofluids as the research object, tests the rheological properties of self-made nanofluids by rheological experiment, and systematically studies the effects of concentration, temperature and shear action on the viscosity of nanofluids, and the dynamic viscoelasticity and thixotropy of nanofluids were discussed. The results show that the rheological type of nanofluid belongs to power-law fluid, but it is related to the shear rate. The viscosity of nanofluids increases with the increase of concentration; when the temperature increases, the viscosity of nanofluids decreases and the fluidity increases; under the shear action, the viscosity of nanofluid changes very little and has good shear resistance; the dynamic viscoelastic test shows that the storage modulus G´ of the nanofluid is larger than the loss modulus G”, showing elastic characteristics; the thixotropy test shows that when the shear rate is accelerated, the viscosity decreases with time, and when the shear rate is slowed down, the viscosity recovers rapidly with time, which has good thixotropy. The research results provide an important theoretical basis for further research on the application of nanomaterials in tight oil and gas reservoirs.

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.

Analysis of Tight Gas Reservoir Forming Condition in Gulong-Changjiaweizi Region, Northern Songliao Basin

2013 ◽  
Vol 652-654 ◽  
pp. 2478-2483
Author(s):  
Xue Juan Zhang ◽  
Shuang Fang Lu ◽  
Wei Huang ◽  
Lei Zhang
Keyword(s):  
Source Rock ◽  
Songliao Basin ◽  
Tight Gas ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Gas Accumulation ◽  
Gas Source ◽  
Geological Conditions ◽  
Tight Gas Reservoir ◽  
Sandstone Reservoir

This paper makes systematic analysis of geological factors of natural gas accumulation in Denglouku formation of Gulong-Changjiaweizi region, including reservoir characteristics, gas source condition, source-reservoir relationship, structural condition, etc. It turned out that K1d2 in Gulong-Changjiaweizi region is generally typical tight sandstone reservoir with low porosity and permeability due to the poor physical properties. The gas source rock of K1d2 formation has larger gas producing capacity.The relationship between source rock and reservoir shows as interbed interfinger or directly contiguity contact, which is beneficial for large-area gas accumulation. The gas generation area of source rock in this region is always in the center and slow downdip direction of Gulong depression with a smaller dip angle on the adjacent tight sandstone reservoir, where faults are rare. The result of comprehensive analysis shows that K1d2 formation in Nothern Songliao Basin and its neighboring layers could be considered as a favorable target of the tight gas reservoir study in Northern Songliao Basin due to its favorable geological conditions of deep basin tight gas reservoir generation, such as tight reservoir, sufficient gas source, communicating source-reservoir relationship and constant flattened structure.

scholarly journals Quantitative evaluation of geological fluid evolution and accumulated mechanism: in case of tight sandstone gas field in central Sichuan Basin

2021 ◽  
Author(s):  
Ya-Hao Huang ◽  
You-Jun Tang ◽  
Mei-Jun Li ◽  
Hai-Tao Hong ◽  
Chang-Jiang Wu ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Raman Shift ◽  
Burial Depth ◽  
Tight Gas ◽  
Fluid Accumulation ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Tight Gas Reservoir ◽  
Homogenization Temperatures ◽  
Central Sichuan Basin

AbstractTight gas exploration plays an important part in China’s unconventional energy strategy. The tight gas reservoirs in the Jurassic Shaximiao Formation in the Qiulin and Jinhua Gas Fields of central Sichuan Basin are characterized by shallow burial depths and large reserves. The evolution of the fluid phases is a key element in understanding the accumulation of hydrocarbons in tight gas reservoirs. This study investigates the fluid accumulation mechanisms and the indicators of reservoir properties preservation and degradation in a tight gas reservoir. Based on petrographic observations and micro-Raman spectroscopy, pure CH4 inclusions, pure CO2 inclusions, hybrid CH4–CO2 gas inclusions, and N2-rich gas inclusions were studied in quartz grains. The pressure–volume–temperature–composition properties (PVT-x) of the CH4 and CO2 bearing inclusions were determined using quantitative Raman analysis and thermodynamic models, while the density of pure CO2 inclusions was calculated based on the separation of Fermi diad. Two stages of CO2 fluid accumulation were observed: primary CO2 inclusions, characterized by higher densities (0.874–1.020 g/cm3) and higher homogenization temperatures (> 210 °C) and secondary CO2 inclusions, characterized by lower densities (0.514–0.715 g/cm3) and lower homogenization temperatures: ~ 180–200 °C). CO2 inclusions with abnormally high homogenization temperatures are thought to be the result of deep hydrothermal fluid activity. The pore fluid pressure (44.0–58.5 MPa) calculated from the Raman shift of C–H symmetric stretching (v1) band of methane inclusions is key to understanding the development of overpressure. PT entrapment conditions and simulation of burial history can be used to constrain the timing of paleo-fluid emplacement. Methane accumulated in the late Cretaceous (~ 75–65 Ma), close to the maximum burial depth during the early stages of the Himalayan tectonic event while maximum overpressure occurred at ~ 70 Ma, just before uplift. Later, hydrocarbon gas migrated through the faults and gradually displaced the early emplaced CO2 in the reservoirs accompanied by a continuous decrease in overpressure during and after the Himalayan event, which has led to a decrease in the reservoir sealing capabilities. The continuous release of overpressure to present-day conditions indicates that the tectonic movement after the Himalayan period has led to a decline in reservoir conditions and sealing properties.

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.

Sign in / Sign up

Export Citation Format

Share Document