Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin

The Yinggehai Basin is a typical high temperature and high pressure (HTHP) gas-bearing basin. The pressure coefficient exceeds 2.2 in deeply-buried Miocene reservoirs in the Ledong Slope, a nondiapir zone in the Yinggehai Basin. Determining the overpressure mechanisms and predicting the pore pressure are key issues for natural gas exploration and development in the Ledong Slope. In this paper, overpressure mechanisms were investigated according to the analysis of vertical effective stress-logging responses and geological evaluations, and the pore pressure was predicted using the Bowers method. The loading-unloading crossplots indicated that the overpressure that existed in reservoirs mainly consists of two types: neighbor-source and allo-source overpressure. The neighbor-source overpressure is mainly caused by the pressure transmission from the adjacent mudstone to the reservoir, with a pressure coefficient less than 1.5 ~ 1.6. The high-magnitude overpressure points with pressure coefficients greater than 1.6 show a typical unloading response, indicating elevated sandstone pressures rather than in situ mudstone pressures, which are most likely to be generated by overpressure vertical transfer. The high-magnitude overpressure fluid generated by the high mature ultradeep buried N1s source rock migrated to the shallower reservoirs via hidden faults/microfractures, which led to the vertical transfer of overpressure. Vertically transferred overpressure was generated at 1.5 ~0.2 Ma, which is beneficial for the preservation of overpressure in lenticular sandbodies. The estimated pore pressure by the Bowers method is in good agreement with the measured pressure and provides a meaningful reference for predrilling pressure prediction in nondiapir or diapir zones in the Yinggehai Basin.

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In situ stress analysis in the Yinggehai Basin, northwestern South China Sea: Implication for the pore pressure-stress coupling process

Marine and Petroleum Geology ◽

10.1016/j.marpetgeo.2016.06.008 ◽

2016 ◽

Vol 77 ◽

pp. 341-352 ◽

Cited By ~ 12

Author(s):

Rui Liu ◽

Jianzhang Liu ◽

Weilin Zhu ◽

Fang Hao ◽

Yuhong Xie ◽

...

Keyword(s):

South China Sea ◽

Stress Analysis ◽

Pore Pressure ◽

South China ◽

In Situ Stress ◽

Coupling Process ◽

Yinggehai Basin ◽

Pressure Stress ◽

In Situ Stress Analysis

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In-situ stress, stress-dependent permeability, pore pressure and gas-bearing system in multiple coal seams in the Panguan area, western Guizhou, China

Journal of Natural Gas Science and Engineering ◽

10.1016/j.jngse.2017.10.009 ◽

2018 ◽

Vol 49 ◽

pp. 110-122 ◽

Cited By ~ 30

Author(s):

Shida Chen ◽

Dazhen Tang ◽

Shu Tao ◽

Hao Xu ◽

Junlong Zhao ◽

...

Keyword(s):

Pore Pressure ◽

In Situ Stress ◽

Coal Seams ◽

Stress Dependent ◽

Western Guizhou ◽

Gas Bearing ◽

Bearing System

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Construction pore pressures in clay foundations under embankments. Part II: generalized behaviour

Canadian Geotechnical Journal ◽

10.1139/t78-006 ◽

1978 ◽

Vol 15 (1) ◽

pp. 66-82 ◽

Cited By ~ 28

Author(s):

S. Leroueil ◽

F. Tavenas ◽

C. Mieussens ◽

M. Peignaud

Keyword(s):

Pore Pressure ◽

Case History ◽

Pressure Coefficient ◽

Geographical Location ◽

A Value ◽

Pore Pressures ◽

Geological Origin ◽

Observed Behaviour ◽

Analysis Of Stability ◽

Vertical Effective Stress

The pore pressures observed under 30 embankments on clays of widely varying geological origin and geographical location are analysed to confirm the validity of the concepts developed from the Saint-Alban case history presented in Part I.It is shown that a significant consolidation does occur in all but one case in the early stages of embankment construction. As a result the vertical effective stress increases rapidly to a value equal to Pc. For further loading on the then normally consolidated clay the pore pressure coefficient [Formula: see text] assumes a value of 1.0.The observed behaviour is interpreted by means of the YLIGHT model of clay behaviour proposed by Tavenas and Leroueil and is shown to apply directly to all clays with an overconsolidation ratio less than 2.5, and with some modifications to heavily overconsolidated clays.The consequences of this behaviour on the analysis of stability and settlements of embankments are presented.

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Prediction of Properties of Marine Sand by In-Situ Measurement of Wave Induced Pore Pressure

Coastal Engineering 1986 ◽

10.1061/9780872626003.101 ◽

1987 ◽

Author(s):

Yoshihiko Maeno ◽

Takashi Hasegawa

Keyword(s):

Pore Pressure ◽

In Situ Measurement ◽

Prediction Of Properties ◽

Marine Sand ◽

Wave Induced

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Least‐squares inversion of in‐situ sonic Q measurements: Stability and resolution

Geophysics ◽

10.1190/1.1707056 ◽

2004 ◽

Vol 69 (2) ◽

pp. 378-385 ◽

Cited By ~ 9

Author(s):

Aristotelis Dasios ◽

Clive McCann ◽

Timothy Astin

Keyword(s):

High Resolution ◽

Least Squares ◽

Instantaneous Frequency ◽

Spectral Ratio ◽

Full Waveform ◽

Multiple Measurements ◽

Sandstone Reservoir ◽

Gas Bearing

We minimize the effect of noise and increase both the reliability and the resolution of attenuation estimates obtained from multireceiver full‐waveform sonics. Multiple measurements of effective attenuation were generated from full‐waveform sonic data recorded by an eight‐receiver sonic tool in a gas‐bearing sandstone reservoir using two independent techniques: the logarithmic spectral ratio (LSR) and the instantaneous frequency (IF) method. After rejecting unstable estimates [receiver separation <2 ft (0.61 m)], least‐squares inversion was used to combine the multiple estimates into high‐resolution attenuation logs. The procedure was applied to raw attenuation data obtained with both the LSR and IF methods, and the resulting logs showed that the attenuation estimates obtained for the maximum receiver separation of 3.5 ft (1.07 m) provide a smoothed approximation of the high‐resolution measurements. The approximation is better for the IF method, with the normalized crosscorrelation factor between the low‐ and high‐resolution logs being 0.90 for the IF method and 0.88 for the LSR method.

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In situ estimation of the coefficient of consolidation in clays

Canadian Geotechnical Journal ◽

10.1139/t90-006 ◽

1990 ◽

Vol 27 (1) ◽

pp. 58-67 ◽

Cited By ~ 5

Author(s):

Mohammed G. Kabir ◽

Alan J. Lutenegger

Keyword(s):

Key Words ◽

Pore Pressure ◽

Reference Values ◽

Time Factors ◽

In Situ Tests ◽

Coefficient Of Consolidation ◽

Oedometer Test ◽

Undisturbed Samples ◽

Oedometer Tests

An investigation was conducted to demonstrate the applicability of cylindrical piezocone and flat piezoblade tests for providing reliable estimates of the coefficient of consolidation in clays. Coefficients of consolidation were calculated from piezocone dissipation tests for different degrees of consolidation using theoretical time factors to provide a comparison with laboratory oedometer tests. Three techniques were developed to calculate the coefficient of consolidation from piezoblade dissipation tests. Results from in situ pore pressure dissipation tests were compared with laboratory oedometer tests performed on undisturbed samples oriented in both the vertical and horizontal directions, to provide reference values of cv and ch. The results of investigations conducted at several clay sites are presented. Key words: in situ tests, piezocone, piezoblade, coefficient of consolidation, oedometer test, clays.

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In-Situ Stresses and Pore Pressure Prediction of a Well in an Iranian Southwest Oil Field

10.3997/2214-4609.202020038 ◽

2020 ◽

Author(s):

M. Motahari ◽

H. Ameri

Keyword(s):

Pore Pressure ◽

Oil Field ◽

In Situ Stresses ◽

Pore Pressure Prediction

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Developing an in situ, hydromechanical coupling, true triaxial rock compression tester and investigating the deformation patterns of reservoir bank slopes

Quarterly Journal of Engineering Geology and Hydrogeology ◽

10.1144/qjegh2021-043 ◽

2021 ◽

pp. qjegh2021-043

Author(s):

Lei Fan ◽

Meiwan Yu ◽

Aiqing Wu ◽

Yihu Zhang

Keyword(s):

Coupling Effect ◽

Water Pressure ◽

Pressure Coefficient ◽

Hydromechanical Coupling ◽

Rock Interaction ◽

True Triaxial ◽

Rock Structure ◽

Deformation Patterns

Interactions between water and rocks are the main factors affecting the deformation of rock masses on sloped banks by reservoir impoundment. The technology used in laboratory tests of water-rock interaction mechanisms cannot simulate the coupling of water, the rock structure and the initial stress environment. In this work, we develop an in situ hydromechanical true triaxial rock compression tester and apply it to investigate the coupling response of reservoir bank rocks to changing groundwater levels. The tester is composed of a sealed chamber, loader, reactor, and device for measuring deformation, which are all capable of withstanding high water pressures, and a high-precision servo controller. The maximum axial load, lateral load and water pressure are 12 000 kN, 3 000 kN and 3 MPa, respectively. The dimensions of the test specimens are 310 mm×310 mm×620 mm. The test specimens are grey-black basalts with well-developed cracks from the Xiluodu reservoir area. The results show that increasing water pressure promotes axial compression and lateral expansion, while decreasing water pressure causes axial expansion and lateral compression. A water pressure coefficient, K, is introduced as a measure of the hydromechanical coupling effect (expansion or compression) with changing groundwater level. A mechanical tester can be used to perform accurate field tests of the response of wet rocks to hydromechanical coupling. The test results provide new information about the deformation patterns of rock slopes in areas surrounding high dams and reservoirs.Thematic collection: This article is part of the Role of water in destabilizing slopes collection available at: https://www.lyellcollection.org/cc/Role-of-water-in-destabilizing-slopes

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Dithienylpyrrole Electrografting on a Surface through the Electroreduction of Diazonium Salts

Electrochem ◽

10.3390/electrochem1010003 ◽

2020 ◽

Vol 1 (1) ◽

pp. 20-31

Author(s):

Thi Huong Le ◽

Van Quyen Nguyen ◽

Gaelle Trippe-Allard ◽

Jean-Christophe Lacroix ◽

Pascal Martin

Keyword(s):

Electron Transfer ◽

Redox Potential ◽

Diazonium Salts ◽

Organic Thin Film ◽

Organic Film ◽

Aniline Derivative ◽

Standard Redox Potential ◽

Key Issues ◽

Adhesion Process

The control of the interface and the adhesion process are key issues for the development of new application based on electrochromic materials. In this work the functionalization of an electrode’s surface through electroreduction of diazonium generated in situ from 4-(2,5-di-thiophen-2-yl-pyrrol-1-yl)-phenylamine (SNS-An) has been proposed. The synthesis of the aniline derivative SNS-An was performed and the electrografting was investigated by cyclic voltammetry on various electrodes. Then the organic thin film was fully characterized by several techniques and XPS analysis confirms the presence of an organic film based on the chemical composition of the starting monomer and allows an estimation of its thickness confirmed by AFM scratching measurements. Depending on the number of electrodeposition cycles, the thickness varies from 2 nm to 10 nm, which corresponds to a few grafted oligomers. In addition, the grafted film showed a good electrochemical stability depending on the scan rates up to 400 V/s and the electrochemical response of the modified electrode towards several redox probes showed that the attached layer acts as a conductive switch. Therefore, the electrode behaves as a barrier to electron transfer when the standard redox potential of the probe is below the layer switching potential, whereas the layer can be considered as transparent towards the electron transfer for redox probes with a redox potential above it.

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