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

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.

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

Geofluids ◽

10.1155/2021/6631006 ◽

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.

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

Lithosphere ◽

10.2113/2021/4336062 ◽

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.

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Performance Evaluation and Mechanism Study of a Silicone Hydrophobic Polymer for Improving Gas Reservoir Permeability

21st Century Surface Science - a Handbook ◽

10.5772/intechopen.90811 ◽

2020 ◽

Author(s):

Jie Zhang ◽

Xu-Yang Yao ◽

Bao-Jun Bai ◽

Wang Ren

Keyword(s):

Surface Tension ◽

Water Saturation ◽

Gas Production ◽

Spontaneous Imbibition ◽

Wettability Alteration ◽

Mechanism Study ◽

Gas Reservoirs ◽

Tension Reduction ◽

Surface Tension Reduction ◽

Reservoir Permeability

The permeability of tight gas reservoirs is usually lower than 1 md. When the external fluids from drilling and completion processes invade such reservoirs, formation damage occurs and causes serious damage to oil and gas production. Fluorocarbon surfactants are most often recommended for removing such damage because they have extremely low surface tension, which means that they can change the reservoir wettability from water wet to gas or oil wet. However, they are not normally applied in the field because they are not cost-effective. Besides, some environmental concerns also restrict their application. In this work, we studied the effects of an oligomeric organosilicon surfactant (OSSF) on wettability modification, surface tension reduction, invasion of different fluids, and fluid flow back. It was found that the amount of spontaneous imbibition and remaining water could be reduced by the surfactant as a result of surface tension reduction and wettability alteration. Compared to the distilled water, the concentration of 0.20 wt% OSSF could decrease water saturation of cores by about 4%. At a flow-back pressure of 0.06 and 0.03 MPa after 20 PV displacement, permeability recovery could increase from 8 to 7–93% and 86%, respectively. We also found that the mechanism of OSSF includes the physical obstruction effect, surface tension reduction of external fluids, and wettability alteration of the reservoir generated. Meanwhile, quantum chemical calculations indicated that adsorbent layer of polydimethylsiloxane could decrease the affinity and adhesion of CH4 and H2O on the pore surface.

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

Energies ◽

10.3390/en14133918 ◽

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.

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All-Time Modeling of Co-Current Spontaneous Water Imbibition Into Gas-Saturated Rocks Using a Novel Transition Time

Journal of Energy Resources Technology ◽

10.1115/1.4048528 ◽

2020 ◽

Vol 143 (6) ◽

Author(s):

Lin Jia ◽

Kewen Li ◽

Lipeng Zhao ◽

Bhekumuzi Mgijimi Mahlalela

Keyword(s):

Water Saturation ◽

Spontaneous Imbibition ◽

Production Performance ◽

Petroleum Reservoir ◽

Gas Reservoirs ◽

Time Model ◽

Water Imbibition ◽

Time Modeling ◽

Capillary Pressures ◽

Saturation Profile

Abstract Spontaneous imbibition (SI) into a porous medium is an important transport phenomenon in petroleum reservoir engineering. The study of spontaneous water imbibition is critical to predict the production performance in these reservoirs developed by waterflooding, especially in the fractured gas reservoirs with active aquifers. While some studies have been reported to characterize spontaneous water imbibition into gas-saturated rocks, they are either limited or inaccurate due to the fact that the existing models have specific assumptions that cannot be applied in other time intervals. To this end, we proposed a novel transition imbibition time t* and developed an all-time (including both early- and later-time SI) model to match the experimental SI data. Furthermore, we proposed a novel model to estimate capillary pressures at different water saturations and to characterize the water saturation profile in capillary-dominated stage. Comparison with the existing capillary pressure estimation models was performed to test the differences. The results demonstrated that the all-time model could fit the experimental imbibition data of the entire SI process satisfactorily. The new saturation model established in this paper can be well fitted with the water saturation profile measured by the X-ray computer tomography (CT) scanners. The results and findings from this work may be of great significance in many areas related to SI, particularly in the development of naturally fractured gas reservoirs with active aquifers.

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Determination of Reservoir Permeability Based on Irreducible Water Saturation and Porosity from Log Data and FZI (Flow Zone Indicator) from Core Data

10.2523/17429-ms ◽

2014 ◽

Author(s):

M. Fazel Alavi ◽

M. Fazel Alavi

Keyword(s):

Water Saturation ◽

Flow Zone ◽

Log Data ◽

Core Data ◽

Reservoir Permeability ◽

Irreducible Water Saturation

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Uncertainty Assessment of Production Performance for Shale-Gas Reservoirs

10.2523/16866-abstract ◽

2013 ◽

Cited By ~ 1

Author(s):

Jiang Xie ◽

Seong H. Lee ◽

Zhiming Wang ◽

Xian-Huan Wen

Keyword(s):

Shale Gas ◽

Uncertainty Assessment ◽

Production Performance ◽

Gas Reservoirs ◽

Shale Gas Reservoirs

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Investigations of water saturation and fractal characteristics in tight sandstone gas reservoirs using centrifugation and NMR experiments

International Journal of Oil Gas and Coal Technology ◽

10.1504/ijogct.2021.114069 ◽

2021 ◽

Vol 26 (4) ◽

pp. 405

Author(s):

Aifen Li ◽

Weibing Tian ◽

Xiaoxia Ren ◽

Shuaishi Fu ◽

Dongdi Cui ◽

...

Keyword(s):

Water Saturation ◽

Gas Reservoirs ◽

Tight Sandstone ◽

Fractal Characteristics

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Experimental Study on the Saturation Model of Volcanic Rock Based on Fluid Distribution

Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description ◽

10.30632/pjv62n4-2021a6 ◽

2021 ◽

Vol 62 (4) ◽

pp. 422-433

Author(s):

Baozhi Pan ◽

◽

Weiyi Zhou ◽

Yuhang Guo ◽

Zhaowei Si ◽

...

Keyword(s):

Volcanic Rock ◽

Oil And Gas ◽

Water Saturation ◽

Early Stage ◽

Evaluation Model ◽

Acoustic Velocity ◽

Distribution Model ◽

Fluid Distribution ◽

Water Drainage ◽

Gas Reservoirs

A saturation evaluation model suitable for Nanpu volcanic rock formation is established based on the experiment of acoustic velocity changing with saturation during the water drainage process of volcanic rock in the Nanpu area. The experimental data show that in the early stage of water drainage, the fluid distribution in the pores of rock samples satisfies the patchy formula. With the decrease of the sample saturation, the fluid distribution in the pores is more similar to the uniform fluid distribution model. In this paper, combined with the Gassmann-Brie and patchy formula, the calculation equation of Gassmann-Brie-Patchy (G-B-P) saturation is established, and the effect of contact softening is considered. The model can be used to calculate water saturation based on acoustic velocity, which provides a new idea for the quantitative evaluation of volcanic oil and gas reservoirs using seismic and acoustic logging data.

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