Producing pore pressure profiles based on theoretical models in undrilled, deepwater frontier basins

2015 ◽  
Vol 3 (1) ◽  
pp. SE13-SE32 ◽  
Author(s):  
Sam Green ◽  
Stephen A. O’Connor ◽  
Deric E. L. Cameron ◽  
James E. Carter ◽  
William Goodman ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Deep Water ◽  
Seismic Velocity ◽  
Theoretical Models ◽  
Seal Failure ◽  
Fracture Pressure ◽  
Pore Pressures ◽  
Pressure Profiles ◽  
Model Pore

A working petroleum system was established on the shelf in offshore Labrador with the Bjarni H-81 discovery in 1973 in the Hopedale Basin. The same reservoirs as those targeted on the shelf are present in the deep water, which is currently receiving attention as the result of newly acquired seismic data. To date, only a very small number of wells have been drilled in the deep water, i.e., Blue H-28, Orphan Basin, and none off mainland Labrador. The wells that were drilled in the deep water had encountered significant overpressure, e.g., kicks that indicated overpressures of 26,850 kPa in the Mid-Cretaceous. Therefore, it was reasonable to assume that pore pressures be similarly high for any new deepwater prospects identified. To help reduce the risk in unexplored environments, we developed an approach that can be adopted to model pore pressure in deepwater settings, with Labrador as the main case study area featured, but also we discussed other global examples such as the Vøring Basin, Mid-Norway. Our results indicated, as a first approximation, that seismic velocity-based pore pressures in shale-rich intervals were similar to the geologic model down to the Lower Tertiary. Deep lithologies were, by regional analogue, likely affected by cementation that will act to preserve overpressure generated by disequilibrium compaction by reducing permeability but will not generate additional pore pressure. The cements (and any carbonate or volcanic lithologies) will, however, result in faster shales and will underpredict pore pressure by mimicking low porosity. A theoretical or “geologic modeling” approach can be used to sense-check any pore pressure interpretation from seismic velocity. The geologic approach also can be used to assess the risk for mechanical seal failure by allowing for estimates of the pore pressure, and related fracture pressure, to be made without the effects of cementation that affect the logs and seismic velocity data.

Producing Pore Pressure Profiles Based on Theoretical Models in Un-drilled Deep-water Frontier Basins

2014 ◽  
Author(s):  
S.A. O'Connor ◽  
S. Green ◽  
W. Goodman ◽  
N. Heinemann ◽  
A. Edwards ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Deep Water ◽  
Theoretical Models ◽  
Pressure Profiles

Predrill pore-pressure prediction and pore pressure and fluid loss monitoring during drilling: A case study for a deepwater subsalt Gulf of Mexico well and discussion on fracture gradient, fluid losses, and wellbore breathing

2014 ◽  
Vol 2 (1) ◽  
pp. SB45-SB55 ◽  
Author(s):  
Fernando Enrique Ziegler ◽  
John F. Jones
Keyword(s):  
Gulf Of Mexico ◽  
Pore Pressure ◽  
Horizontal Stress ◽  
Fluid Loss ◽  
Pressure Profiles ◽  
Pore Pressure Prediction ◽  
Fracture Gradient ◽  
Minimum Horizontal Stress ◽  
Fluid Losses

In this case study, the overburden, pore-pressure, and fracture gradients are calculated for several nearby analog wells and subsequently used to generate a predrill pore-pressure prediction for the deepwater subsalt Gulf of Mexico well, Flying Dutchman, located in Green Canyon 511 no. 1 (OCS-G 22971). Two key analog wells penetrated the lower Miocene and have sufficient data to generate pore-pressure profiles. Subsequently, the predrill pore-pressure prediction is found to be in good agreement with the pore pressure estimated from well logs while drilling. During the drilling phase of the Flying Dutchman well, two zones of significant fluid loss and wellbore breathing were encountered and are evaluated as a means of determining the formation types where they are most likely to occur, as well as their related minimum horizontal stress and fracture gradient.

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.

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.

scholarly journals Determining Fracture Pressure Gradients from Well Logs

2020 ◽  
Vol 8 (1) ◽  
pp. 5
Author(s):  
Udo K. I ◽  
George N. J ◽  
Akankpo A. O ◽  
Azuoko G. B ◽  
Aka M.U
Keyword(s):  
Niger Delta ◽  
Well Logs ◽  
Pressure Gradients ◽  
Seal Failure ◽  
Fracture Pressure ◽  
Shear Wave Velocities ◽  
Pore Pressures ◽  
Sonic Log ◽  
Drilling Operations ◽  
Sonic Logs

Fracture pressure gradient is one of the essential parameters used in determining mud weight profiles during drilling operations. We have determined fracture pressure gradients from well logs obtained from three producing wells in Onshore Niger Delta using an empirical model. Key logs needed for the prediction were conditioned and quality controlled to meet the standard required for reliable results. The true vertical stress, normal compaction trend and compressional shale velocity trends were generated from the logs (density and sonic logs). Poison’s ratio was obtained from compressional and shear wave velocities derived from sonic log. Pore pressures in the three wells were then predicted using Eaton’s Method. The predicted pore pressures, overburden pressures and poison’s ratio were used to determine fracture pressures using Ben Eaton’s Model. Results showed that there is a suitable drilling margin at all depths only in well G-005. Drilling well A-001 to a depth of 10962.81 ft and K-001 to a depth of 12626.9 ft will fracture the formations because the fluid pressures at those depths approximate the fracture pressures of 8536.7psi and 9506 psi with corresponding gradients of 0.78 psi/ft and 0.75 psi/ft respectively. The implication is that drilling deeper in the field will results in very low seal capacity magnitudes, thereby presenting a higher risk of top-seal failure.  

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
Sign in / Sign up

Export Citation Format

Share Document