scholarly journals Physical Simulation Experimental Technology and Mechanism of Water Invasion in Fractured-Porous Gas Reservoir: A Review

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3918
Author(s):  
Mengfei Zhou ◽  
Xizhe Li ◽  
Yong Hu ◽  
Xuan Xu ◽  
Liangji Jiang ◽  
...  
Keyword(s):  
Physical Simulation ◽  
Water Saturation ◽  
Production Capacity ◽  
Future Trend ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Saturation Field ◽  
Time Dynamic ◽  
Well Pattern ◽  
Experimental Technology

In the development process for a fractured-porous gas reservoir with developed fracture and active water, edge water or bottom water easily bursts rapidly along the fracture to the production well, and the reservoir matrix will absorb water, reducing the gas percolation channel and increasing the gas phase percolation resistance of the reservoir matrix, therefor reducing the stable production capacity and recovery efficiency of the gas reservoir. For this reason, this paper investigates physical simulation experimental technology and mechanisms as reported by both domestic and foreign scholars regarding water invasion in fractured-porous gas reservoirs. In this paper, it is considered that the future trend and focus of water invasion experiments will be to establish a more realistic three-dimensional physical model on the basis of fine geological description, combined with gas reservoir well pattern deployment and production characteristics, and to fully consider the difference between horizontal and vertical water invasion along the reservoir side; at the same time, dynamic parameters such as model pressure field and water saturation field can be obtained in real time. Based on this understanding of the water invasion mechanism of fractured-porous gas reservoirs, we propose the next research direction and the development countermeasures such as water controls, drainage, and dissolved water seals and water locks to combat water invasion in reservoirs, along with the injection of gas to replenish formation energy, etc., so as to slow down and control the influence of water invasion.

Stress Sensitivity of Low Permeable and Water-Bearing Gas Reservoir without Gas Slippage Effect

2014 ◽  
Vol 962-965 ◽  
pp. 570-573
Author(s):  
Jian Yan ◽  
Xiao Bing Liang ◽  
Qian Wu ◽  
Qing Guo
Keyword(s):  
Water Saturation ◽  
Stress Sensitivity ◽  
Testing Methods ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Well ◽  
Well Production ◽  
Gas Slippage ◽  
Slippage Effect ◽  
Function Relationship

Because of the gas slippage, the testing methods of stress sensitivity for gas reservoir should be different from that for oil reservoir. This text adopts the method that imposing back pressure on the outlet of testing core to weaken the gas slippage effect and tests the stress sensitivity of low permeability gas reservoirs, then analyzes the influence of permeability and water saturation on stress sensitivity. The results show that: low permeable and water-bearing gas reservoirs have strong stress sensitivity; the testing permeability has the power function relationship with net stress, compared to the exponential function, the fitting correlation coefficient is larger and more suited to the actual; the lower the permeability is and the higher water saturation is, the stronger the stress sensitivity is. The production of gas well is affected when considering the stress sensitivity, so the pressure dropping rate should be reasonable when low permeable gas reservoirs are developed. The results provide theoretical references for analyzing the well production and numerical simulation.

scholarly journals Comparative Study on the Reservoir Characteristics and Development Technologies of Two Typical Karst Weathering-Crust Carbonate Gas Reservoirs in China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Haijun Yan ◽  
Ailin Jia ◽  
Fankun Meng ◽  
Qinyu Xia ◽  
Wei Xu ◽  
...  
Keyword(s):  
Carbonate Reservoirs ◽  
Production Performance ◽  
Dynamic Monitoring ◽  
Weathering Crust ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Field ◽  
Reservoir Characteristics ◽  
Reservoir Stimulation ◽  
Well Pattern

Carbonate reservoirs are the main reservoir types in China, which occupy the large ratio of reserves and production at present. The high-efficiency development of carbonate reservoirs is of great significance to assure the stability of national energy supply. The Lower Paleozoic reservoir in Jingbian gas field and the Sinian reservoir in Anyue gas field are two typical carbonate gas reservoirs, and their successful development experiences can provide significant references for other similar carbonate gas reservoirs. For Jingbian gas field, it is a lithological-stratigraphic reservoir developed in a westward monocline and multiple rows of nose-fold structures, and is a stable craton basin with simple palaeognomy distribution and stable connectivity, which has complex gas-water distribution. However, for Anyue gas field, it is a lithological-structural reservoir with multiple tectonic high points and multiple fault systems, and is biological dune beach facies under extensional setting with highly differentiated inside of the block in palaeognomy characteristics, which has limited connectivity and tectonic side water is in a local area. The difference of gas reservoir characteristics leads to the diverse development strategies. For these two gas reservoirs, although there are some similar aspects, such as the screen of enrichment areas, the application of irregular well pattern and reservoir stimulation techniques, the criteria of enrichment areas, the well types, and the means of reservoir stimulation are absolutely different. In addition, due to the differences of control reserves and production capacity for these two kinds of reservoirs, the mode of stable production is also different. The effective development of Jingbian gas field can give some references to the future exploitation on the Sinian gas reservoir. Firstly, the sedimentary characteristics should be studied comprehensively. Secondly, the distribution pattern and distribution characteristics of the palaeognomy should be found and determined. Thirdly, the distribution of fracture system in the reservoir should be depicted finely. Finally, dynamic monitoring on the production performance should be strengthened, and the management for this gas field should be improved further. The findings of this study can help for better understanding of the Karst weathering-crust carbonate gas reservoir formation characteristics and the optimal development technologies that should be taken in practice.

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.

Stimulation Mechanism of SDS Nanoemulsion in Tight Gas Reservoirs

2011 ◽  
Vol 418-420 ◽  
pp. 82-85
Author(s):  
Ming Liang Luo ◽  
Jia Lin Liu ◽  
Le Jun Liao ◽  
Zi Long Jia ◽  
Hou Tai Sun
Keyword(s):  
Water Saturation ◽  
Sodium Dodecyl ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Initial Water ◽  
Core Flow ◽  
Tight Gas Reservoir ◽  
Water Block ◽  
Flow Experiments

The stimulation mechanisms of sodium dodecyl sulfate (SDS) nanoemulsion in tight gas reservoir were analyzed by capillary force, core spontaneous imbibitions, cleanup effect and core flow experiments. The results show that SDS nanoemulsion could hold back capillarity effectively, reduce the water absorption and reduce water block damage. The initial water saturation of core decreases by 85.12% and the gas effective permeability regains by 42.03%, which improves the stimulation effect in tight gas reservoir substantially

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.

scholarly journals Physical simulation for water invasion and water control optimization in water drive gas reservoirs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xuan Xu ◽  
Xizhe Li ◽  
Yong Hu ◽  
Qingyan Mei ◽  
Yu Shi ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Physical Simulation ◽  
Control Measures ◽  
Production Performance ◽  
Distribution Analysis ◽  
Water Control ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Well ◽  
Gas Recovery

AbstractThe development of water drive gas reservoirs (WDGRs) with fractures or strong heterogeneity is severely influenced by water invasion. Accurately simulating the rules of water invasion and drainage gas recovery countermeasures in fractured WDGRs, thereby revealing the mechanism of water invasion and an appropriate development strategy, is important for formulating water management measures and enhancing the recovery of gas reservoirs. In this work, physical simulation methods were proposed to gain a better understanding of water invasion and to optimize the water control of fractured WDGRs. Five groups of experiments were designed and conducted to probe the impacts of the distance between the fractures and the gas well, the drainage position, the drainage timing and the aquifer size on the water invasion and production performance of a gas reservoir. The gas and water production and the internal pressure drop were monitored in real time during the experiments. Based on the above experimental works, a theoretical analysis was conducted to quantitatively evaluate the performance of the gas reservoir recovery via the gas well production performance, water invasion, dynamic pressure drop and residual gas and water distribution analysis. The results show that when the fracture scale was appropriate, a gas well drilled close to a fracture (Experiment 1-3) or a high-permeability formation could also produce gas and achieve drainage efficiently. The recovery factor of Experiment 1-3 reached 62.5%, which was 24.6% and 21.1% higher than those of Experiments 1-1 and 1-2, respectively, which had wells drilled in low-permeability areas. Draining water near an aquifer can effectively inhibit water invasion during the early stage of gas recovery. The setup in Experiment 2-1 effectively inhibited water invasion and avoided the formation of water-sealed volumes of gas to recover 30% more gas than recovered with that of Experiment 1-1 without drainage wells. A shorter distance between the drainage well and the aquifer increased the drainage capacity and decreased the gas production capacity, respectively (Well 2 at Point A vs Point B). A larger aquifer had a lower gas recovery, which reduced the economic benefit. For example, due to an infinitely large aquifer, the reserves in Experiment 4-1 were developed by a single well, the gas recovery was only 33.4%. These research results are expected to be beneficial for the preparation of development plans and the optimization of water control measures for WDGRs.

scholarly journals Production Data Analysis and Practical Applications in the Sulige Tight Gas Reservoir, Ordos Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Minhua Cheng ◽  
Wen Xue ◽  
Meng Zhao ◽  
Guoting Wang ◽  
Bo Ning ◽  
...  
Keyword(s):  
Data Analysis ◽  
Ordos Basin ◽  
Gas Production ◽  
Production Data ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Well Pattern ◽  
Tight Gas Reservoir ◽  
Wellbore Pressure

Successful exploitation of tight sandstone gas is one of the important means to ensure the “increasing reserves and production” of the oil and gas initiative and also one of the important ways to ensure national energy security. To further improve the accuracy of historical matching of field data such as gas production and bottom-hole pressure during the production process of this type of gas reservoir, in this study, a new expression of wellbore pressure for the uniform flow of vertical fractured wells in Laplace space based on the point sink function model of vertical fractures in tight sandstone gas reservoirs is constructed. This innovation is based on a typical production data analysis plot of the Blasingame type that uses the numerical inversion decoupling mathematical equation. After analyzing the pressure and pressure derivative characteristics of each flow stage in the typical curves, a new technique of type-curve matching was proposed. In order to verify the correctness of the model and the application value of the field, based on the previous production data of Sulige Gas Field in China, a new set of production data diagnostic chart of tight sandstone gas reservoir was formed. A case analysis showed that the application of the production data analysis method and data diagnosis plot in the field accurately evaluated the development effect of the tight sandstone gas reservoirs, clarified the scale of effective sand bodies, and provided technical support for optimizing and improving the well pattern and realizing the efficient development of gas fields.

scholarly journals Experimental study on production performance and reserves utilization law in carbonate gas reservoirs

2021 ◽  
Author(s):  
Mengfei Zhou ◽  
Xuan Xu ◽  
Yuxuan Zhang ◽  
Chunyan Jiao ◽  
Yu Tang ◽  
...  
Keyword(s):  
Water Saturation ◽  
Production Performance ◽  
Formation Pressure ◽  
Pressure Balance ◽  
Gas Reservoirs ◽  
Reservoir Permeability ◽  
Stable Production ◽  
Well Pattern ◽  
Production Period ◽  
Original Water

AbstractCarbonate gas reservoirs in China are rich in reserves. In the development process, there are many reserves with low permeability, low efficiency and low recovery degree. It is difficult to stabilize gas well production and prolong its life cycle. Under the condition of original water saturation (Sw) of 0%, 20%, 40%, 55% and 65%, respectively, the physical simulation experiment of gas reservoirs depletion development was carried out by using long core multi-point embedded pressure measuring system. The long cores with average gas permeability of 2.300 mD, 0.485 mD and 0.046 mD (assembled from 10 carbonate cores) were used to carry out this experiment. During the experiment, the pressure dynamics at different positions inside the long core and the gas production dynamics at the outlet were recorded in real time to reveal the production performance and reserves utilization law of carbonate gas reservoirs. The results show that the stable production period of tight reservoir in carbonate gas reservoirs is short, and the low production period is relatively long. The stable production time and recovery rate of gas reservoir increase with the increase of reservoir permeability and decrease with the increase of water saturation. The production of tight carbonate gas reservoirs with permeability less than 0.1 mD is greatly affected by pore water, and the reservoir pressure distribution shows a steep pressure drop funnel, and the reserves far from well are rarely used. Therefore, the reserves far from well should be utilized by closing well to restore formation pressure balance, densifying well pattern or transforming reservoir. The variation range of water saturation in the development of carbonate gas reservoirs is influenced by reservoir permeability and water saturation, and closely related to formation pressure gradient in production process. It decreases with the increase of reservoir permeability and increases with the increase of original water saturation. The research results provide a theoretical basis for understanding the relationship between physical properties of carbonate gas reservoirs and production performance, reserves utilization law, and realizing balanced utilization, efficient development and long-term stable production of carbonate gas reservoirs.

Discussion on the Disappearance of Transition Flow of Fractured Gas Reservoir with Pressure Transient Analysis

2012 ◽  
Vol 594-597 ◽  
pp. 2495-2499
Author(s):  
Yun He Su ◽  
Xiao Hua Liu
Keyword(s):  
Transient Analysis ◽  
Water Saturation ◽  
Double Porosity ◽  
Transition Flow ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Production Time ◽  
Pressure Transient Analysis ◽  
Storage Coefficient ◽  
Wellbore Storage

In recent years, more and more fractured gas reservoirs were discovered in the world. In general, fractured gas reservoirs are defined as formation with double porosity system, which is composed with fissure and matrix. In reservoirs with double porosity system, only the fissure system are connected with the wellbore and have relatively high permeability, matrix rocks have very low permeability, gas can flow into the wellbore only via fissures, and the flow process be divided into the flow in fissures, transition flow and the flow in the total system. But transition flow is not found in the process of well testing, which results in misapplication of development decision support and selection in gas field development program. In this paper, the influent factors of fractured gas reservoir for estimation are studied by models of single well simulation, and the simulated results are analysis by the method of pressure transient analysis. For example: the time of pressure build-up test, production time, wellbore storage coefficient,kv/kh,the reservoir boundary, the pressure precision, the porosity of matrix and fracture, the permeability of matrix and fracture, the thickness of formation(partial perforation),skin, water saturation etc. The results of simulation show that the disappearance of the transition flow is caused by many factors, which include that the time of pressure build-up test is short, production time is not sufficiently long, ,the vertical permeability is much larger than the horizontal permeability and the formation is perforated partially, the time of the reservoir boundary for pressure is short than the transition flow, the porosity of matrix is close to the porosity of fracture, the permeability of matrix much smaller than the fracture permeability, the pressure precision is low. The transition flow is not affected by the skin, the wellbore storage coefficient and water saturation, which cover up the radial flow in fissure system.

scholarly journals Physical Simulation for Water Invasion and Water Control Optimization in Water Drive Gas Reservoirs

2021 ◽  
Author(s):  
xuan xu ◽  
Xizhe li ◽  
yong hu ◽  
yu shi ◽  
qingyan mei ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Physical Simulation ◽  
Control Measures ◽  
Production Performance ◽  
Distribution Analysis ◽  
Water Control ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Well ◽  
Gas Recovery

Abstract The development of water drive gas reservoirs (WDGRs) with fractures or strong heterogeneity is severely influenced by water invasion. Accurately simulating the rules of water invasion and drainage gas recovery countermeasures in fractured WDGRs, thereby revealing the mechanism of water invasion and an appropriate development strategy, is important for formulating water management measures and enhancing the recovery of gas reservoirs. In this work, physical simulation methods were proposed to gain a better understanding of water invasion and to optimize the water control of fractured WDGRs. Five groups of experiments were designed and conducted to probe the impacts of the distance between the fractures and the gas well, the drainage position, the drainage timing and the aquifer size on the water invasion and production performance of a gas reservoir. The gas and water production and the internal pressure drop were monitored in real time during the experiments. Based on the above experimental works, a theoretical analysis was conducted to quantitatively evaluate the performance of the gas reservoir recovery via the gas well production performance, water invasion, dynamic pressure drop and residual gas and water distribution analysis. The results show that when the fracture scale was appropriate, a gas well drilled close to a fracture (Experiment 1–3) or a high-permeability formation could also produce gas and achieve drainage efficiently. The recovery factor of Experiment 1–3 reached 62.5%, which was 24.6% and 21.1% higher than those of Experiments 1–1 and 1–2, respectively, which had wells drilled in low-permeability areas. Draining water near an aquifer can effectively inhibit water invasion during the early stage of gas recovery. The setup in Experiment 2 − 1 effectively inhibited water invasion and avoided the formation of water-sealed volumes of gas to recover 30% more gas than recovered with that of Experiment 1–1 without drainage wells. A shorter distance between the drainage well and the aquifer increased the drainage capacity and decreased the gas production capacity, respectively (Well 2 at Point A vs Point B). A larger aquifer had a lower gas recovery, which reduced the economic benefit. For example, due to an infinitely large aquifer, the reserves in Experiment 4 − 1 were developed by a single well, the gas recovery was only 33.4%. These research results are expected to be beneficial for the preparation of development plans and the optimization of water control measures for WDGRs.

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