scholarly journals WELL-SEISMIC INTEGRATION TO PORE PRESSURE PREDICTION USING MULTIVARIATE GEOSTATISTICS: A CASE STUDY IN A BRAZILIAN EQUATORIAL MARGIN BASIN

2020 ◽  
Vol 38 (1) ◽  
pp. 32
Author(s):  
Flávia Braz Ponte ◽  
Francisco Fábio de Araújo Ponte ◽  
Adalberto Silva ◽  
Alberto Garcia Figueiredo
Keyword(s):  
Pressure Gradient ◽  
Pore Pressure ◽  
Seismic Velocity ◽  
Multivariate Geostatistics ◽  
Geostatistical Approach ◽  
Pore Pressure Prediction ◽  
Pore Pressure Gradient ◽  
Gradient Models ◽  
Pressure Analysis

ABSTRACT. Pore pressure modeling has been fundamental on several applications and stages of hydrocarbon exploration, evaluation, development and production. Pore pressure estimation is generally obtained from seismic velocity data and pore pressure analysis on wells. There are many methods available for pore pressure analysis, although more recently the application of the geostatistical approach is increasing in popularity and proving to be an important method for pore pressure gradient prediction in challenging areas where pore pressure prediction is difficult using deterministic methods. In this case study on a new frontier area in the Brazilian Equatorial Margin, multivariate geostatistics allowed integration of data at different scales and spatial variations of seismic and well variables produce pore pressure gradient models. The final result is a geopressure model where one can easily extract well-conditioned pore pressure information at any location.Keywords: geostatistical approach, different scales, pore pressure gradient models. INTEGRAÇÃO POÇO-SÍSMICA PARA PREDIÇÃO DE PRESSÃO DE POROS USANDO A GEOSTATÍSTICA MULTIVARIADA: UM ESTUDO DE CASO EM UMA BACIA DA MARGEM EQUATORIAL BRASILEIRARESUMO. A modelagem de pressão de poros tem sido fundamental em diversas aplicações e etapas da exploração, avaliação, desenvolvimento e produção de hidrocarbonetos. Em geral, a estimativa de pressão de poros é obtida a partir da integração de dados de velocidade sísmica e análise de pressão em poços. Existem diversos métodos para análise de pressão de poros, entretanto, atualmente, a aplicação da abordagem geoestatística está crescendo em popularidade e provando ser um importante método para predição de gradiente de pressão de poros em áreas de fronteiras onde a previsão de pressão de poros usando métodos determinísticos não é bem sucedida. Neste estudo de caso, localizado em uma área de nova fronteira na Margem Equatorial Brasileira, a geoestatística multivariada permitiu a integração das variáveis sísmicas e de poço em diferentes escalas e variações espaciais e a obtenção de modelos de gradiente de pressão de poros. Os resultados geraram um modelo de geopressão no qual a extração de valores de pressão de poros bem condicionados é simples em qualquer parte da área.Palavras-chave: abordagem geostatistica, diferentes escalas, modelos de gradiente depressão de poros.

scholarly journals COMPARING TWO MULTIVARIATE GEOSTATISTICS TOOLS FOR PORE PRESSURE PREDICTIVE MODELLING

2019 ◽  
Vol 37 (4) ◽  
pp. 471
Author(s):  
Flávia Braz Ponte ◽  
Francisco Fábio de Araújo Ponte ◽  
Adalberto Silva ◽  
Alberto Garcia Figueiredo Jr
Keyword(s):  
High Pressure ◽  
Pore Pressure ◽  
Seismic Velocity ◽  
Predictive Modelling ◽  
Pressure Gradients ◽  
Multivariate Geostatistics ◽  
Interval Velocity ◽  
Pressure Fields ◽  
Collocated Cokriging ◽  
Pore Pressure Prediction

 ABSTRACT. Pore pressure prediction has been an increasing concern during well designing due to the numerous accidents recorded because of mistaken estimations of high pressure fields. This paper depicts a predictive modelling of pore pressure using multivariate geostatistics tools called LVM and collocated cokriging. The resulting maps of LVM and collocated cokriging were compared. Geostatistics were used to estimate pore pressure distribution in unsampled places considering the two different scales and spatial variation from well measurements (pore pressure) and 3D seismic velocity data. When pore pressure gradients recorded in the wells have been defined and the seismic interval velocity analyzed, pore pressure estimation can be done by using the geostatistics approaches. This is a method for estimating the geopressure field distribution at basin or reservoir level that offers the advantage of the possibility of extracting pore pressure information at any place.Keywords: geostatistics approaches, LVM, collocated cokriging, high pressure fields.RESUMO. Devido aos numerosos acidentes registrados por estimativas equivocadas de campos de alta pressão, a preocupação com a previsão de pressão de poros tem aumentado durante projetos de poços. Este artigo descreve uma modelagem para previsão de pressão de poros usando duas ferramentas da geoestatística multivariada, a LVM e a cokrigagem colocada. Neste estudo, essas duas metodologias foram comparadas. A geoestatística foi utilizada para estimar a distribuição de pressão de poros em locais não amostrados, permitindo a integração dos dados das duas variáveis, velocidade sísmica e dados de poço, em diferentes escalas e variação espacial. Quando os gradientes de pressão de poros, registrados em poços, são definidos e a velocidade intervalar da sísmica é analisada, existindo correlação entre eles, a previsão de pressão de poros pode ser feita utilizando a abordagem geoestatística. A vantagem de uma modelagem geoestatística 3D de gradiente pressão de poros é a possibilidade de extração de informação de pressão em qualquer local dentro da área modelada.Palavras-chave: abordagem geoestatística, LVM, cokrigagem colocada, campos de alta pressão.

Pore-pressure prediction derived by common-reflection-surface (CRS) stacking seismic velocity to prevent drilling problems in geopressure zones: a case study of Snapper Field, Gippsland Basin, Australia

2013 ◽  
Vol 53 (2) ◽  
pp. 485
Author(s):  
Goldy Oceaneawan ◽  
Noer Samsoe ◽  
Telaga Kautsar ◽  
Aditya Suharsono ◽  
Leksono Mucharam
Keyword(s):  
Pore Pressure ◽  
Seismic Velocity ◽  
Velocity Model ◽  
Pressure Data ◽  
Common Reflection Surface ◽  
Pore Pressure Prediction ◽  
Victorian Department ◽  
Accuracy Of Prediction ◽  
Gippsland Basin

Snapper Field is located in the Gippsland Basin, Australia. The field was discovered in 1968, and then continued by development drilling from the Snapper A platform, which started in 1981. The geopressure zones were encountered below 3,200 m at the Snapper—1 well and below 2,800 m at the Snapper A—21 well. If these zones are not anticipated before drilling, they could create problems, such as sticking, kick, or blowout. This extended abstract presents a technique to predict pore pressure from seismic velocity, where the seismic velocity was derived by CRS. Many case studies have shown that CRS stack could produce smooth macro-velocity model, which is more reliable to be used for pore pressure prediction. Eaton's equation was used to transform the seismic velocity derived by CRS to pore pressure as a function of depth. All of these workflows have been conducted using field data from the Snapper Field provided by the Victorian Department of Primary Industries. The prediction was compared with actual well pressure data to test the accuracy of prediction. The comparison shows that the pressure, which has been generated using this technique, is accurate. This result could be applied when making drilling programs particularly to identify the geo-pressure zones for wildcat/exploration wells in another field when pressure data from neighbouring wells are unavailable. If these geo-pressure zones could be anticipated, it will reduce drilling risk operation.

Seismic velocity-based pore pressure prediction in a complex overpressure mechanism area: A case study from offshore Myanmar, Moattama Basin

2019 ◽  
Author(s):  
Prat Boonyasatphan ◽  
Akkarapol Sakulraungsri ◽  
Helge Sognnes ◽  
Saksit Sa-nguanphon ◽  
Pariyakorn Som-in ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Seismic Velocity ◽  
Pore Pressure Prediction

Ahead of Bit Pore Pressure Prediction using VSP - A Case Study in South China Sea

2010 ◽  
Author(s):  
Yuhong Xie ◽  
Jun Cai ◽  
Ling Xia Zhen ◽  
Hong Tian ◽  
Yan Hua Li ◽  
...  
Keyword(s):  
South China Sea ◽  
Pore Pressure ◽  
South China ◽  
China Sea ◽  
Pore Pressure Prediction

Possible Reason of the Dependence of an Apparent Permeability on the Pressure Gradient at low Flow Rates in Laboratory Study

2021 ◽  
Author(s):  
Nikolay Baryshnikov ◽  
Evgeniy Zenchenko ◽  
Sergey Turuntaev
Keyword(s):  
Pressure Gradient ◽  
Pore Pressure ◽  
Pore Space ◽  
Low Flow ◽  
Pressure Gradients ◽  
Apparent Permeability ◽  
Flow Rates ◽  
Rock Samples ◽  
Pore Pressure Gradient ◽  
Filtration Properties

<p>Currently, a number of studies showing that the injection of fluid into the formation can cause induced seismicity. Usually, it is associated with a change in the stress-strain state of the reservoir during the pore pressure front propagation. Modeling this process requires knowledge of the features of the filtration properties of reservoir rocks. Many researchers note the fact that the measured permeability of rock samples decreases at low pressure gradients. Among other things, this may be due to the formation of boundary adhesion layers with altered properties at the interfaces between the liquid and solid phases. The characteristic thickness of such layer can be fractions of a micron, and the effect becomes significant when filtering the fluid in rocks with a comparable characteristic pore size. The purpose of this work was to study the filtration properties of rock samples with low permeability at low flow rates. Laboratory modeling of such processes is associated with significant technical difficulties, primarily with the accuracy limit of measuring instruments when approaching zero speed values. The technique used by us to conduct the experiment and data processing allows us to study the dependence of the apparent permeability on the pore pressure gradient in the range of 0.01 MPa/m, which is comparable to the characteristic pressure gradients during the development of oil fields. In the course of the study, we carried out laboratory experiments on limestone core samples, during which the dependencies of their apparent permeability on the pore pressure gradient were obtained. We observed a significant decrease in their permeability at low flow rates. In the course of analyzing the experimental results, we proposed that a decrease in apparent permeability may occur due to the effect of even a small amount of residual gas in the pore space of the samples. This has been confirmed by additional experiments. The possibility of clogging of core sample pore space must be considered when conducting when conducting laboratory studies of the core apparent permeability.</p>

scholarly journals Unsteady Seepage Behavior of an Earthfill Dam During Drought-Flood Cycles

Geosciences ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 17 ◽  
Author(s):  
Ziyang Li ◽  
Wei Ye ◽  
Miroslav Marence ◽  
Jeremy Bricker
Keyword(s):  
Pressure Gradient ◽  
Water Level ◽  
Pore Pressure ◽  
Internal Erosion ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Upstream Slope ◽  
Earthfill Dams ◽  
The Stability ◽  
Pore Pressure Gradient

Climate change with extreme hydrological conditions, such as drought and flood, bring new challenges to seepage behavior and the stability of earthfill dams. Taking a drought-stricken earthfill dam of China as an example, the influence of drought-flood cycles on dam seepage behavior is analyzed. This paper includes a clay sample laboratory experiment and an unsteady finite element method seepage simulation of the mentioned dam. Results show that severe drought causes cracks on the surface of the clay soil sample. Long-term drought causes deeper cracks and induces a sharp increase of suction pressure, indicating that the cracks would become channels for rain infiltration into the dam during subsequent rainfall, increasing the potential for internal erosion and decreasing dam stability. Measures to prevent infiltration on the dam slope surface are investigated, for the prevention of deep crack formation during long lasting droughts. Unsteady seepage indicators including instantaneous phreatic lines, equipotential lines and pore pressure gradient in the dam, are calculated and analyzed under two assumed conditions with different reservoir water level fluctuations. Results show that when the water level changes rapidly, the phreatic line is curved and constantly changing. As water level rises, equipotential lines shift upstream, and the pore pressure gradient in the dam’s main body is larger than that of steady seepage. Furthermore, the faster the water level rises, the larger the pore pressure gradient is. This may cause internal erosion. Furthermore, the case of a cracked upstream slope is modelled via an equivalent permeability coefficient, which shows that the pore pressure gradient in the zone beneath the cracks increases by 5.9% at the maximum water level; this could exacerbate internal erosion. In addition, results are in agreement with prior literature that rapid drawdown of the reservoir water level is detrimental to the stability of the upstream slope based on embankment slope stability as calculated by the Simplified Bishop Method. It is concluded that fluctuations of reservoir water level should be strictly controlled during drought-flood cycles; both the drawdown rate and the fill rate must be regulated to avoid the internal erosion of earthfill dams.

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