Pressure Drop Characteristics and Reserves Calculation Method of Gas Reservoir of Multi-Layer Unconsolidated Sandstone

Taking Sebei gas field as an example, this paper sorts hydrostatic pressure test data over the years and summarizes the reasons that the formation pressure drop curve generates a straight line, up-warping and recurvation from the perspective of water invasion, perforation adding, layer adjusting, sand burying, and sand control as well as inter-layer interference and inter-well interference, with typical wells analyzed and explained. On this basis, two kinds of mass balance correction models which have taken the offset of the pressure drop curve into account are proposed to calculate the dynamic reserves of gas wells with different offset shapes of pressure drop curves. Practical result shows the simple concept and strong practicality of this method, which provides an effective method for the accurate calculation of dynamic reserves of such gas reservoir.

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Features on Pressure Drop and Methods to Evaluation Reserves of Commingled Unconsolidated Sand Reservoir

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.616-618.907 ◽

2012 ◽

Vol 616-618 ◽

pp. 907-912

Author(s):

Qing Heng Zeng ◽

Jin Pang ◽

Xi Nan Yu ◽

Hong Liu ◽

Qing Ping Zeng

Keyword(s):

Pressure Drop ◽

Test Data ◽

Material Balance ◽

Gas Wells ◽

Gas Field ◽

Sand Burial ◽

Static Test ◽

Water Influx ◽

Unconsolidated Sand ◽

Sand Control

The static test data of past years the Sebei gas field are classified. The reason why the pressure drop-down curve are straight, or ascends or curves downward are analyzed with the characteristic of water influx, reperforating, transfer layers, sand burial, sand control, layers and wells interference of the typical wells. Then, two revised material balance models based on the deviation of pressure drop curve are introduced to calculate the dynamic reserve of this gas field with different pressure drop curves. It was proved that the method is an effective approach to evaluate precisely dynamic reserves of gas wells.

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Productivity Testing and Analysis of Low Permeability and Thick Layer of N Gas Field

E3S Web of Conferences ◽

10.1051/e3sconf/202021302002 ◽

2020 ◽

Vol 213 ◽

pp. 02002

Author(s):

Quan Hua Huang ◽

Xing Yu Lin ◽

Zhi-xing Yang ◽

Ke-feng Lu ◽

Xian-kang Hu

Keyword(s):

Steady State ◽

Statistical Method ◽

Thick Layer ◽

Theory Model ◽

Theoretical Formula ◽

Low Permeability ◽

Testing Time ◽

Gas Wells ◽

Gas Reservoir ◽

Gas Field

For a better guidance of production, a combination of drill stem testing (DST), regional statistical method and pseudo steady-state seepage theory model was used to analyze the productivity of N gas reservoir in light of the complex geological features of the low-permeability thick-layer. Firstly, the DST method was used to test the N gas reservoir. And then the binomial pseudo-pressure method, binomial pressure square method and exponential method were used to interpret the test data of DST of this formation. Finally, the binomial pseudo-pressure interpretation method was used and the results showed that only the productivity of H3b layer was successfully tested of the four. The H3a, H4b and H5a layers are ultra-low pore and permeability gas reservoirs and the productivity of these layers can’t be explained by the available data due to the short testing time and a non-stationary state of testing pressure and quantity, resulting in the failure of the test. The productivity of the main layers were estimated and forecasted by the regional statistical method and the theoretical model of pseudo steady-state seepage, taking the arithmetic average value of the regional statistical method and the theoretical formula as the final value of absolute open flow rates(AOF). The final calculation results are as follows: the AOF of main gas layers H3a, H3b, H4b and H5a in N gas field is 31.30×104m3/d, 388.92×104m3/d, 20.82×104m3/d and 30.80×104m3/d, respectively. This method may sheds light on verifying and calculating the productivity of gas wells and determining the reasonable production allocation of gas wells.

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The Researches on Reasonable Well Spacing of Gas Wells in Deep and low Permeability Gas Reservoirs

E3S Web of Conferences ◽

10.1051/e3sconf/20183801038 ◽

2018 ◽

Vol 38 ◽

pp. 01038

Author(s):

Yu Bei Bei ◽

Li Hui ◽

Li Dong Lin

Keyword(s):

Pressure Gradient ◽

Low Permeability ◽

Well Testing ◽

Gas Wells ◽

Gas Reservoirs ◽

Gas Reservoir ◽

Gas Field ◽

Well Spacing ◽

Start Up ◽

Starting Pressure Gradient

This Gs64 gas reservoir is a condensate gas reservoir which is relatively integrated with low porosity and low permeability found in Dagang Oilfield in recent years. The condensate content is as high as 610g/m3. At present, there are few reports about the well spacing of similar gas reservoirs at home and abroad. Therefore, determining the reasonable well spacing of the gas reservoir is important for ensuring the optimal development effect and economic benefit of the gas field development. This paper discusses the reasonable well spacing of the deep and low permeability gas reservoir from the aspects of percolation mechanics, gas reservoir engineering and numerical simulation. considering there exist the start-up pressure gradient in percolation process of low permeability gas reservoir, this paper combined with productivity equation under starting pressure gradient, established the formula of gas well spacing with the formation pressure and start-up pressure gradient. The calculation formula of starting pressure gradient and well spacing of gas wells. Adopting various methods to calculate values of gas reservoir spacing are close to well testing' radius, so the calculation method is reliable, which is very important for the determination of reasonable well spacing in low permeability gas reservoirs.

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Reserve Estimation from Early Time Production Data in Geopressured Gas Reservoir: Gas Production of Cumulative Unit Pressure Drop Method

Geofluids ◽

10.1155/2021/9926983 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Hongfeng Wang ◽

Xiaoping Li ◽

Hedong Sun ◽

Guangren Meng ◽

Wen Cao ◽

...

Keyword(s):

Pressure Drop ◽

Natural Gas ◽

Gas Production ◽

Correction Coefficient ◽

Formation Pressure ◽

Gas Reservoirs ◽

Reserve Estimation ◽

Straight Line ◽

Deviation Factor ◽

Unit Pressure

There is high uncertainty in reserve estimation during the early development of deep ultrahigh pressure gas reservoirs, largely because it remains challenging in accurately determining the formation compressibility. To overcome this, starting from the definition of compressibility, a novel gas production of cumulative unit pressure drop analysis method was established, of which the effectiveness was proven by applications in calculating the reserves of three gas reservoirs. It has been found that, in the limiting case, i.e., when the formation pressure dropped to the normal atmospheric pressure, the dimensionless gas production of the cumulative unit pressure drop was the reciprocal of the initial formation pressure. Besides, the relationship curve of the dimensionless gas production of the cumulative unit pressure drop and pressure drop was a straight line in the medium term, extending the straight line and intersecting the vertical line passing through the original formation pressure point, and the reserves can be determined according to the intersection point and the initial formation pressure. However, due to the influence of natural gas properties, the value needs further correction, and the correction coefficient depends on the pseudocritical temperature of natural gas. Specifically, when the pseudocritical temperature is given, the correction coefficient would be close to the minimum value of the natural gas deviation factor. When the pseudocritical temperature is more than 1.9 and less than 3.0, the minimum deviation factor would be between 0.90 and 1.0, and the higher the pseudocritical temperature, the closer the ratio is to 1.0.

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Research of Interlayer Interference and Development Strategy of Multilayer Commingled Production Gas Reservoir

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.868.497 ◽

2013 ◽

Vol 868 ◽

pp. 497-502 ◽

Cited By ~ 1

Author(s):

Yu Wu Zhou ◽

Hong Liu ◽

Lin Wang ◽

Xiao Lu Wang ◽

Ya Long Zhang

Keyword(s):

Development Strategy ◽

Interval Length ◽

Gas Wells ◽

Gas Reservoirs ◽

Gas Reservoir ◽

Gas Field ◽

Water Contact ◽

Statistical Function ◽

Contact Distribution

Sebei gas field is featured with the characteristics of the shallow-buried gas reservoir, long gas containing well section, multilayer gas reservoirs beds, the complicated gas/water contact distribution, the water produced obviously, sands produced frequently from the gas wells and the multi-layers gas reservoir extracted unbalancedly in the developing process. For these reasons, the paper proposed the method that interlayer interference coefficients are defined with statistical function. Combined with the data of the sand-layers profile test, the effects of the numbers of different sand-lays, the perforated thickness, the perforated interval length and permeability contrast on the interlayer interference are evaluated and these permeability parameters are optimized.

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Prediction of critical liquid loading time for water-producing gas wells: Effect of liquid drop rotation

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01417-6 ◽

2021 ◽

Author(s):

Xiao Chongyang ◽

Fu Heng ◽

Cheng Leli ◽

Pei Wenyu

Keyword(s):

Liquid Drop ◽

Early Stage ◽

Gas Wells ◽

Liquid Loading ◽

Gas Reservoir ◽

Gas Field ◽

Gas Well ◽

Production Stages ◽

Field Workers ◽

Drainage Effect

AbstractAfter more than 20 years of continuous development, part of the wells in the Moxilei-1 gas reservoir located at the Sichuan Basin have entered the middle–later production stage. With the continuous decline in formation pressure and production rates, some of the gas wells have entered the potential period of liquid loading, while some have already suffered water plugging. Currently, the field engineers usually carry out some corresponding drainage measures after the occurrence of liquid loading in the gas well, which will first affect the production progress of the gas field, then increase the difficulty in drainage and reduce the drainage effect afterward. On the basis of Pan’s model for evaluating critical liquid-carrying flow rate, the influence of liquid drop rotation was considered in the new model. Further, combined with the Arps production decline equation, a prediction model of liquid loading timing was deduced. Taking a typical well in the Moxilei-1 gas reservoir as an example, based on the early-stage production data of the gas well, the model was used to predict the liquid loading timing accurately. The model can predict the possibility and timing of liquid loading in gas wells at different production stages. It can check the gas wells with potential liquid loading, so as to reduce the workload for field workers. Furthermore, it can predict the potential liquid accumulation and its timing in advance, so as to guide the field workers to prepare for drainage in advance.

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