Display of calibration data from drilling or other techlog wellbore software platform tools such as the techlog formation pressure module. This new method is then applied to well and seismic data in deepwater gulf of mexico gom subsalt basins, predicting subsalt and saltexit pore pressure. The pore pressure prediction module adds a complete workflow for interactive geopressure analysis, including prediction at wells and full 3d pressure models. Pore pressure prediction using seismic velocities 1 to optimize drilling decisions and well planning in overpressured areas, it is essential to carry out pore pressure predictions before drilling.
This greatly simplifies the work steps in pore pressure prediction methodology. Influence of pore pressure on wellbore instability. Methodology used to derive the overburden gradient key parameter of terzaghi equation different techniques can be used according to well data available. Pore pressure prediction is the ability to create numerical formulas that mimic the subsurface pressure profile. Depending upon whether the pore pressure is equal to.
The speed of propagation of compressionalwave energy in the subsurface, known simply as formation velocity, is strongly influenced by. Pore pressure prediction in unconventional resources. Pore pressure prediction porosity stress mechanics. The realtime monitoring should ensure that 1 pore pressure is continuously monitored and indicators of the abnormal pressures are identified. Accurate determination of pore pressure is of fundamental importance to prevent circulation losses or blowouts during drilling. Predrill porepressure prediction directly from seismically. Chapter 18 velocity estimation for porepressure prediction. Otm consulting great burgh, yew tree bottom road epsom kt18 5xt. Notable pore pressure prediction methods are hottman and. Pore pressure prediction and modeling using seismic velocities. P is the formation pore pressure psi p ob is the overburden pressure ft z is the vertical depth ft d is the d exponent. View pore pressure prediction research papers on academia. Pore pressure models derived from the integration and careful calibration of.
Current seismic approaches for pore pressure prediction mainly initially establish the relation between vertical effective stress and physical parameters velocity, resistivity or porosity, and then predict pore pressures with the known effective stress theory. Accurate pore pressure prediction in hpht well reduces risk. Jun 14, 2017 predrill prediction of formation pore pressure from surface seismic survey is very important for drilling, production, and reservoir engineering because it affects drilling operations and wellplanning processes. Pdf integrated 1d workflow for porepressure prediction. Challenges in pore pressure prediction for unconventional petroleum systems changrui gong.
Optimizing the mud weight program and planned equivalent circulating density ecd was important to minimize wellbore instability in the 9 7. Calibrate pp to credible information as it becomes available. Pdf pore pressure determination methods researchgate. The relation between net stress and reservoir pore pressure can be defined as see for instance christensen and wang, 1985. Velocity determination for pore pressure prediction. We use cookies to ensure that we give you the best experience on our website.
A detailed description of pore pressure terminology can be found in bruce and bowers 2002, bowers 2002 and dutta 2002. Pore pressure prediction tamu pemex well control lesson. Porepressure prediction is an active and longstanding research area in the earth sciences, and it has been the focus of the petroleum industry since the early days of exploration and exploitation. We include some of these definitions here for convenience. The conventional approach is to use the normally pressured shale section to derive this nct, then apply it to the overpressured shale section to determine the pore pressure.
A modified approach to predict pore pressure using the d exponent method introduction pore pressure prediction is a key factor in petroleum exploration and production operations. Introduction and motivation the knowledge of the stress state, the geological conditions and the formation pore pressure is essential to check the stability of wells. More information on our geomochanics analysis software is available from downunder geosolutions. The first prediction approach by hottman and johnson 1965 method is still used in the industry due to its preciseness in pore pressure prediction. Theoretical pore pressure porosity model is the fundamental for pore pressure prediction in shales, where the compaction disequilibrium is the primary mechanism of overpressure generation. However, without establishing the geological groundwork for these mathematical equations, results can be misleading. The pore pressure is then calculated by subtracting the vertical or mean effective stress from the vertical or mean stress at the depth of a obs. For wildcat drilling, only seismic data are available in the study area.
Pdf during the early stages of the ormen lange slope stability evaluations it. Pore pressure prediction methods using techlog a predrill estimate of formation pore pressure is a key requirement for successful exploration and drilling. A predrill estimate of pore pressure can be obtained from seismic interval velocities using a seismic to pore pressure transform calibrated with laboratory measurements. This method utilises calibrated sonic log velocities from offset well data. Depending upon the magnitude of the pore pressure, it can be classified into three types viz. The implicit assumption, therefore, is that porosity is controlled only by effective stress, driven by mechanical compaction. Pore pressure estimation has become an active field of research in the present. Because seismic velocities correlate with effective pressure in the formation, sufficiently precise estimates of velocity obtained from seismic observations can be used to determine pore pressure. Integrated 1d workflow for porepressure prediction and.
A new pore pressure prediction methodback propagation. Pore pressure prediction in orthotropic medium based on rock. Experience from several unconventional plays highlights key aspects of pore pressure prediction work that are different from conventional exploration settings. Pdf reliable prediction of pore pressure pp is critically important to. An accurate estimation of formation porepressure plays an important role in safe and economic drilling for overpressured sediments. Pore pressure prediction is a method of forecasting by using data that provides information about upcoming events or risks beforehand.
Velocity determination for pore pressure prediction cseg. Indepth 3d velocity model left and pore pressure prediction right in equivalent mud weight using the seismic velocities for the 50mi2 area. Consequently, velocity determination is the key to pore pressure prediction. Pdf pore pressure prediction using probabilistic neural network. Pore pressure prediction from well logs and seismic data in this paper we describe the extensive pore pressure prediction ppp from three given wells namely well1, well2 and well3 and also from the 3d marine seismic data acquired over the same area in the arabian.
When impermeable rocks such as shales form as sediments are compacted, their pore fluids cannot always escape and must then support the total overlying rock column, leading to anomalously high formation pressures. Challenges in pore pressure prediction for unconventional. Pore pressure is the pressure of the fluid in the pore space of the rock, and as mentioned above, when it exceeds the hydrostatic pressure, overpressure situation occurs. Jan 31, 2019 this article aims to reduce the uncertainty of pore pressure prediction in a reservoir with complex lithology using velocitybased methods e.
Pdf pore pressure prediction using eaton and neural network. Integrated 1d workflow for porepressure prediction and mudweight window calculation for subsalt well sections. Challenges of porositybased pore pressure prediction cseg. Therefore, accurate comparison of the alternatives is with respect to this value.
We compare the predicted results with measured pore pressure data where available. Pore pressure calculation in a hydraulicallyconnected formation is introduced. Enhanced velocity based pore pressure prediction using. Pore pressure is defined as the pressure acting on the fluids in the pore spaces of the rock. Accurate pore pressure prediction in hpht well reduces risk, saves rig time.
Muhammad adam bin mahadzira nguyen xuan huyb a affiliation for first. Blowouts, kicks, borehole washouts, wellbore breakout and stuck pipes oughton et al. There are various methods to predict pore pressure from seismic velocity. Pore pressure prediction reduce uncertainty in pore pressure estimations.
The subsurface pore pressure buildup partitions are. Predrill prediction of formation pore pressure from surface seismic survey is very important for drilling, production, and reservoir engineering because it affects drilling operations and wellplanning processes. Enhanced velocitybased porepressure prediction using. When the indicator suggests porosity values that are higher than the trend, then abnormal pressures are suspected to be present. Predrill pore pressure prediction using seismic velocities.
P p is the formation pore pressure psi p p z is the normal pore pressure gradient psi ft1. Apr 11, 2020 download predril pore pressure prediction siesmic. Pore pressure prediction pore pressure predictions and transformations that make use of seismic velocity measurements have a huge impact on drilling safety and the economics of drilling design and well construction. Pdf a new model for pore pressure prediction researchgate. Pore pressure prediction employs a broad range of methodologies to estimate fluid pressures including porosity and depthbased trends, seismic velocities, and multivariate regressions. Pdf pore pressure prediction using geophysical methods in.
The magnitude of the deviation from the normal trend line is used to quantify the abnormal pressure. Pore pressure prediction in unconventional resources onepetro. Calibration and ranking of porepressure prediction models. Impact of pore pressure on reservoir geomechanics depletion and stress changes. The speed of propagation of compressionalwave energy in the subsurface, known simply as formation velocity, is strongly influenced by compaction, particularly in young clastic basins. Pdf overpressure situation can be created in both clastic and nonclastic. The pressure of the subsurface formation fluids, commonly expressed as the density of fluid required in the wellbore to balance that pore pressure. A normal pressure gradient might require 9 lbmgalus 1.
Velocity determination for pore pressure prediction satinder chopraand alan huffman arcis corporation,calgary,alberta,canada. Coupled thermohydromechanicalchemical processes in geosystems. Investigation and prediction of pore pressure and effective free download as powerpoint presentation. However, a number of different compaction trends can be. Fusion petroleum technologies,houston,usa summary knowledge of formation pore pressure is not only essential for safe and costeffective drilling of wells, but is also critical. Pitfalls in porosity based pore pressure prediction. Porepressure prediction employs a broad range of methodologies to estimate fluid pressures including porosity and depthbased trends, seismic velocities, and multivariate regressions. The pressure of fluids within the pores of a reservoir, usually hydrostatic pressure, or the pressure exerted by a column of water from the formations depth to sea level. Without a proper input of the pore pressure an adjusted prediction becomes impossible to obtain for any geomechanical model. Case histories from the gulf of mexico selim simon shaker, geopressure analysis services, houston, tx coordinated by rob holt a comprehensive framework and fresh perspective to pore pressure predic tion methods and algorithms based on the. Pore pressure is notoriously difficult to predict and may vary significantly across a typical sedimentary basin. Using this theoretical model, pore pressure prediction from porosity and compressional velocity sonic transit time have been obtained. A predrill estimate of pore pressure can be obtained from seismic.
Pore pressure estimation what can we learn from 4d. Pdf pore pressures in most deep sedimentary formations are not hydrostatic. Pore pressure prediction is critical to reducing drilling costs and exploring hydrocarbons. Fuyong yan and dehua han, rock physics lab, university of houston.
Pore pressure calculation methods dug insight user manual. Pdf pore pressure prediction in the planning of the drilling well commonly carried out. Model of pore pressure prediction using a neural network. Prediction of pore water pressure buildup and liquefaction of sands during earthquakes by the cyclic strain method by. Pore pressure prediction is a key factor in petroleum exploration and production operations. Scribd is the worlds largest social reading and publishing site. During the exploration phase, knowledge of the spatial distribution of formation pressures can be used to develop fluid migration models, to study the effectiveness of seals, and to rank. Realtime pore pressure prediction in depleted reservoirs using. Pore pressure prediction from well logs and seismic data.
Predrill pore pressure prediction is not a trivial task and requires a clear understanding of the lithology and geomechanical state of the reservoir. Estimation of density using compaction law with depth. An overview of pore pressure prediction using seismically. If it is not properly evaluated, it can lead to numerous drilling problems such as dangerous well kicks, lost circulation, blowouts, stuck pipe, excessive costs, and borehole. Predrill pore pressure prediction and safe well design on the top of. Accurate pore pressure prediction in hpht well reduces. Pore pressure prediction free download as powerpoint presentation. Pore pressure prediction is required in order to carry out safe drilling and well completion job. It is useful because it enables drilling to continue without any delays or incidents. However, its prediction an essential step of any hydrocarbon exploration and exploitation program. A quantitative predrill prediction of pore pressure is required when drilling in overpressured formations, and can be obtained. These limitations can be traceable to the following main factors. Predrill porepressure prediction directly from seismically derived acoustic impedance abstract to design well paths that minimize risk and avoid drilling hazards such as blowouts and stuck pipe, drilling engineers would like to have a quantitative understanding of the overpressure zones in the subsurface.
Calculate dexponent to predict pore pressure trends. Investigation and prediction of pore pressure and effective. A predrill estimate of formation pore pressure is a key requirement for successful exploration and drilling. The pore pressure prediction module is utilised to estimate the effective stress. Pore pressure is the pressure of fluids in the pores of a rock formation. Modern modeling technologies for petroleum systems provide a complementary approach to traditional methods of pressure prediction. Uncertainty, realtime updating and how real time updating reduces uncertainty ahead of the bit. If you continue to use this site we will assume that you are happy with it. Model building is typically characterized by an iterative sequence that includes model identification, calibration, selection, and diagnostic checking. Pore pressure models derived from the integration and careful calibration of traditional wireline. Notable pore pressure prediction methods are hottman and johnson, equivalent depth eatons 1975 and bowers 1995 methods. Understanding pore pressure prediction in unconventional plays is important for executing a safe drilling strategy and for accurate production modeling.
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