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. Pore pressure prediction from well logs and seismic data. Introduction a pore pressure analysis is premised upon predicting the pressure in shale. A new pore pressure prediction from compressional velocity and sonic transit time are proposed. Pore pressure prediction from seismic data using neural. The magnitude of the deviation from the normal trend line is used. This method first assumes that there is a depth section over which the pore pressure is hydrostatic, and the sediments are normally compacted because of the systematic increase in effective stress with depth. 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. Prediction and evaluation of abnormal formation pressure and. Presented at the spe annual technical conference and exhibition, new orleans, louisiana, 30 september3 october. 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.
A detailed description of pore pressure terminology can be found in bruce and bowers 2002, bowers 2002 and dutta 2002. The estimates are either used by geologists or mud engineers for safety by identifying the potential drilling hazards. The challenge of pore pressure prediction in complex. In conjunction with a specified grain density, and a density for the saturating brine, the reference. Pore pressure prediction porosity stress mechanics.
Most petroleum provinces exhibit overpressures, and as the industry explores for deeper targets, encountering high overpressures is becoming more common. Eatons equation eatons method equations for ppp are described in figure 3, and can be made from either velocity slowness or resistivity measurements, in the well or from data volumes. Predrill pore pressure estimation has been obtained from transform models using. This theory indicates that pore pressure in the formation is a. Velocity determination for pore pressure prediction satinder chopraand alan huffman arcis corporation,calgary,alberta,canada. Pore pressure prediction is required in order to carry out safe drilling and well completion job. Pore pressure prediction has gradually became an integral part in the oil and gas industry as it provides the estimates for pore pressure in reservoirs or wells. It is known that pore pressure pp is an integral part for the well planning process. Pore pressure, bowers method, tau method, selforganizing map, lithofacies.
Pore pressure prediction from seismic data using neural network. Seismic pore pressure prediction with uncertainty using a. Pore pressure prediction in drilling engineering, methods used to estimate formation pressure can be divided into two categories. This approach, at best, will only give a local, empirical fit, and in reality, the next well drilled may encounter very different pore pressures. 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. Pore fluid pressure affects the physical properties of reservoir rocks, hence predicted pressure is a key input when building the geomechanical model of a reservoir. Applications are presented in deepwater and subsalt wells to improve pore pressure.
Predrill porepressure prediction directly from seismically. Pore pressure predictionpore pressure prediction improve your techniques and learn from the expert. Malo location we had some measured pore pressure data purple squares and blue triangles at the end of the target zone only, in figure 6. Pore pressure is the pressure of fluids in the pores of a rock formation. Johnsons method for pore pressure prediction uses a crossplot to relate departures of a pore pressure indicator from the normal trend line to the pore pressure gradient at that depth. 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. When the indicator suggests porosity values that are higher than the trend, then abnormal pressures are suspected to be present. Experience from several unconventional plays highlights key aspects of pore pressure prediction work that are different from conventional exploration settings. For predrill pore pressure prediction, pore pressure can be obtained from seismic velocities using a velocityto pore pressure transform sayers et al. Pressure prediction in shales from wireline data is reliant on the ability to define a normal compaction trend, and deviations from this trend allow calculation of the magnitude of pore pressure. Changes in pore pressure can be recognized on regular formation evaluation tools such as sonic, resistivity, porosity, and density logs.
Enhanced velocitybased porepressure prediction using. A normal pressure gradient might require 9 lbmgalus 1. Eatons equation and yans equation are widely used in pore pressure prediction. When drilling, two kinds of pressure can be predicted which are. Predrill pore pressure prediction using seismic velocities. Through vigilant monitoring and interpretation of the pore pressure data our analysts are able to help mitigate drilling. A reliable pore pressure prediction can translate into considerable savings in terms of drilling costs and safety. Pore pressure prediction using seismic velocity modeling. Gas kick results in delay in drilling practice as steps are taken to balance the pressure in the well and this can be. Origin and prediction of abnormal formation pressures.
Farkha petroleum engineering department, koya university, iraq abstract oil and gas well drilling planning is the main task of any drilling engineer. A predrill estimate of pore pressure can be obtained from seismic. Velocity based pore pressure prediction methods are widely accepted as a routine tech nique in the petroleum. A predrill estimate of pore pressure can be obtained from seismic interval velocities using a seismic to pore pressure transform calibrated with laboratory measurements. Pore pressures in shale can be predicted and from that sand and shale pressure can be projected. In order to overcome this task, it is required to maintain the wellbore pressure. The purposes of this study are 1 predict the formation pore, and fracture pressure gradients, 2 determine the most applicable methods for formation pressure prediction, and 3 determine the.
Chapter 18 velocity estimation for pore pressure prediction. We include some of these definitions here for convenience. A new petrophysically constrained predrill pore pressure prediction method for the deepwater gulf of mexico. Using this method needs the establishment of the crossplot which means a lot of statistical work. The density and sonic logs were used respectively to generate the shale trend and the shale normal. Fundamental investigation of pore pressure prediction during drilling from the mechanical behavior of rock. The speed of propagation of compressionalwave energy in the subsurface, known simply as formation velocity, is strongly influenced by.
Velocity determination for pore pressure prediction. Pore pressure of formations is one of the main worries of drillers in the exploration areas today. The variation in encountered pore pressure is due to porosity varying by other. Over 10 million scientific documents at your fingertips.
The pressure of the subsurface formation fluids, commonly expressed as the density of fluid required in the wellbore to balance that pore pressure. Through vigilant monitoring and interpretation of the pore pressure data our analysts are able to help mitigate drilling risks and signi. During the exploration phase, a prediction of pore pressure can. For predrill pore pressure prediction, pore pressure can be obtained from seismic velocities using a velocitytoporepressure transform sayers et al. During the exploration phase, a prediction of pore pressure can be used to evaluate exploration risk factors including the migration of formation fluids and seal integrity. However, without establishing the geological groundwork for these mathematical equations, results can be misleading. Calculation of abnormal pore pressure during drilling. The pore pressure prediction module is utilised to estimate the effective stress. Modern modeling technologies for petroleum systems provide a complementary approach to traditional methods of pressure prediction.
Eni spa 1999 overpressure evaluation manual, company manual, pp 141170. Sep 14, 2016 pore pressure prediction using geolog. To calculate pore pressure with respect to newly established clusters, velocity versus effective stress scatter plots were created for each cluster independently. However, due to lack of rft data in clusters 3 and 5, power regression fit was applied only to clusters 1, 2 and 4. Niranjan banik, adam koesoemadinata, charles wagner, charles inyang, and huyen bui, schlumbergerwesterngeco. This course introduces the attendee to the basics of the geopressure calculator gpc and fracture pressure calculator fpc modules within rokdoc. Predrill prediction of formation pore pressure from surface seismic survey is very. However, its prediction an essential step of any hydrocarbon exploration and exploitation program.
Formation pressure in regions with upthrown and downthrown blocks uplift and subsidence of sedimentary rocks. Traditional methods used to determine pore pressure are based on either logs e. Pore pressure the pore pressure may also be referred to as formation pressure and is the fluid pressure within the pores of a soil or rock. Pore pressure prediction and modeling using seismic velocities. Enhanced velocity based pore pressure prediction using. To apply the porepressure transform, density at all locations were determined to calculate 3d volume of pressure. A global algorithm for pore pressure prediction delta geophysics. Understanding pore pressure prediction in unconventional plays is important for executing a safe drilling strategy and for accurate production modeling. The eaton method is an empirical method to estimate pore pressures from sonic, resistivity, and density logs which are calibrated to measured. Aade05ntce12 five things your pore pressure analyst. Pore pressure prediction free download as powerpoint presentation.
Coupled thermohydromechanicalchemical processes in geosystems. Seismic driven pore pressure prediction joanne wang. Pore pressure prediction can offer timely warning of the possibility of a gas kick so that the driller can modify the mud weight well before a kick is allowed to happen. The realtime monitoring should ensure that 1 pore pressure is continuously monitored and indicators of the abnormal pressures are identified. One example of analysis using a trend line is the equivalent depth method illustrated in fig.
Pdf calibrated predrill pore pressure prediction from 3d. Pore pressure prediction has been a vital concern to the oil and gas industry for many decades. Eatons equation eatons method equations for ppp are described in figure 3, and can be made from either velocity slowness or resistivity measurements, in. A theoretical pore pressure model is proposed based on effective stressporositycompaction theory. The seismic velocities have lower resolution for well planning purposes. Using datasets from the gulf of mexico the course introduces some of the basic concepts of overburden calculation, pore pressure prediction and fracture pressure calculation, but is not intended to be a comprehensive. Challenges in pore pressure prediction for unconventional petroleum systems. The pdf file you selected should load here if your web browser has a pdf reader.
Pressure predictive methods are based on seismic velocities transit times, offset well logs, and. Scribd is the worlds largest social reading and publishing site. A new pore pressure prediction methodback propagation. Chapter 18 velocity estimation for porepressure prediction. Pore pressure is notoriously difficult to predict and may vary significantly across a typical sedimentary basin. To design well paths that minimize risk and avoid drilling hazards such as blowouts and stuck pipe, drilling engineers. When pore pressure exceeds the normal pressure, it is overpressure. Standard practice is to calibrate the normal compaction curve to the shallowest data as these data are most likely to be normally pressured. Pdf abnormal pore pressure can cause some problems during the drilling process such as a blowout or sticking pipe while drilling. Accurate pore pressure prediction in hpht well reduces. Integrated 1d workflow for porepressure prediction and mudweight window calculation for subsalt well sections conference paper pdf available june 2015 with 580 reads how we measure reads. Therefore, accurate comparison of the alternatives is with respect to this value. 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. Integrated approach to pore pressure and fracture pressure.
Accurate pore pressure prediction in hpht well reduces risk. Without a proper input of the pore pressure an adjusted prediction becomes impossible to obtain for any geomechanical model. Seismic driven pore pressure prediction paradigm ltd. Methods to determine pore pressure equivalent depth methods. An output pdf for pore pressure is then calculated point by point in the 3d model, using either a linearized gaussian approximation or a sequential stochastic simulation approach that fully accounts for nonlinearities in the velocity to pore pressure transform and. Estimation and prediction of abnormally low pressures in basins in permafrost regions. The two major pore pressure prediction techniques employed are the eatons and bowers models while the eatons fracture pressure model and the hubbert and willis fracture pressure prediction models were utilized for fracture prediction.
Pore pressure analysis mainly includes three aspects, that is, predrill pore pressure prediction, realtime pore pressure detection, and postwell analysis. 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. Optimizing the mud weight program and planned equivalent circulating density ecd was important to minimize wellbore instability in the 9 7. 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. To optimize drilling decisions and well planning in abnormal pressured areas, it is essential to carry out pore pressure predictions before. 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.
Pore, abnormal formation and fracture pressure prediction f. If predrill pore pressure prediction has big uncertainty, realtime pore pressure detection is needed to update predrill pore pressure prediction and advise drilling operations in realtime. Pore pressure prediction in unconventional resources. Pdf integrated 1d workflow for porepressure prediction. Geopressure or pore pressure prediction is of central importance in both the exploration and development of hydrocarbon reservoirs. Research highlights pore pressure prediction methods are modified using depthdependent normal compaction equations. However, a number of different compaction trends can be. Pore pressure models derived from the integration and careful calibration of traditional wireline. The prediction of pore pressure for the abnormally pressured i. Pdf the aim of this work is to present an integrated workflow for the onedimensional 1d analysis of pore pressure pp prediction and mudweight. Predrill pore pressure prediction using seismic velocities data on. Whether we are dealing with deep water wells, frontier exploration wells or deviated wells in depleted reservoirs, it is necessary to design and deliver safe and cost effective wells.
Pore pressure estimation is important for both exploration and drilling projects. Extensive experience on workover, completion logging interpretation and design. Pdf calibrated predrill pore pressure prediction from 3d seismic for the cocuite field, veracruz basin colin m sayers academia. Indepth 3d velocity model left and pore pressure prediction right in equivalent mud weight using the seismic velocities for the 50mi2 area. Velocity determination for pore pressure prediction cseg. Pore, abnormal formation and fracture pressure prediction. Origin of overpressure and pore pressure prediction in the. Pore pressure prediction reduce uncertainty in pore pressure estimations. Consequently, velocity determination is the key to pore pressure prediction. The subsurface pore pressure buildup partitions are. The relation between net stress and reservoir pore pressure can be defined as see for instance christensen and wang, 1985. Pore pressure prediction is the ability to create numerical formulas that mimic the subsurface pressure profile.
Razak damit5 1 australian school of petroleum, adelaide, australia 2 deeppp exploration technologg,ies crc, adelaide, australia. 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. An output pdf for pore pressure is then calculated point by point in the 3d model, using either a linearized gaussian approximation or a sequential stochastic simulation approach that fully accounts for nonlinearities in the velocity to pore pressure transform and spatial correlation between the different input. Pdf pore pressures in most deep sedimentary formations are not hydrostatic. Realtime pore pressure prediction in depleted reservoirs using. A new method for pore pressure prediction using logging and. Predrill pore pressure prediction directly from seismically derived acoustic impedance. Predrill pore pressure prediction using seismic velocities for.
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