Eatons equation eatons method equations for ppp are described in figure 3, and can be made from either velocity slowness or resistivity measurements, in. Farkha petroleum engineering department, koya university, iraq abstract oil and gas well drilling planning is the main task of any drilling engineer. Best practices, wider skills sets, and competencies all viewed as essential for. Pdf pore pressure prediction using eaton and neural network. Using geological constraints, limits are established on hydrocarbon column height. Boasting a success rate of over 90% out of 250 wells analyzed, the team anticipates pressure levels prior to drilling operations in order to determine the optimal configuration and mud program. Therefore, accurate comparison of the alternatives is with respect to this value. Pore pressure prediction using geophysical methods in carbonate reservoirs. Pore pressure prediction is a key factor in petroleum exploration and production operations. Current commonly used methods of pore pressure prediction are based on the difference between a normal trend in sonic wave velocity, formation resistivity factor frf, or dexponent a function. 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. Chapter 18 velocity estimation for porepressure prediction. Zor according to the mining schedule are important in the prediction of porepressure distribution within the slope. Pore pressure prediction from well logs and seismic data.
Display of calibration data from drilling or other techlog wellbore software platform tools such as the techlog formation pressure module. Pdf pore pressures in most deep sedimentary formations are not hydrostatic. Gas kick results in delay in drilling practice as steps are taken to balance the pressure in the well and this can be. Experience from several unconventional plays highlights key aspects of pore pressure prediction work that are different from conventional exploration settings. Pore pressure is the pressure of fluids in the pores of a rock formation. 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. Enhanced velocity based pore pressure prediction using. Muhammad adam bin mahadzira nguyen xuan huyb a affiliation for first.
Pore pressure prediction in unconventional resources. The pore pressure prediction module is utilised to estimate the effective stress. Origin of overpressure and pore pressure prediction in the. However, without establishing the geological groundwork for these mathematical equations, results can be misleading. An overview of pore pressure prediction using seismically. Pore pressure calculation methods dug insight user manual. The speed of propagation of compressionalwave energy in the subsurface, known simply as formation velocity, is strongly influenced by. Pore, abnormal formation and fracture pressure prediction. Impact of pore pressure on reservoir geomechanics depletion and stress changes. Consequently, velocity determination is the key to pore pressure prediction. If the pore pressure is predicted inaccurately, costly damage to the well or reservoir can occurresulting in npt and safety hazards. Changes in pore pressure can be recognized on regular formation eval uation tools such as sonic, resistivity, porosity, and density logs. Cn101163990b quantitative risk assessment applied to. Velocity determination for pore pressure prediction cseg.
A predrill estimate of pore pressure can be obtained from seismic. Influence of pore pressure on wellbore instability. Predrill pore pressure and fracture gradient predictions obtained from seismic velocity data are used in well design taking into account uncertainties in the velocity estimation and in the models that use the velocities to determine pore pressure. Pore, abnormal formation and fracture pressure prediction f. Seismic interval transit times derived pore pressures and actual pore pressures derived from logs in a drilled well at an offset location are used to correlate graphically or analytically the seismic. 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. 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. 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. To optimize drilling decisions and well planning in abnormal pressured areas, it is essential to carry out pore pressure predictions before. We include some of these definitions here for convenience. A global algorithm for pore pressure prediction delta geophysics. Pore pressure estimation what can we learn from 4d.
The pore pressure prediction unit, established in 2008, is tasked with studying and predicting formation pressure levels during exploration. A method of predicting pore pressures at a proposed drilling location using interval transit times derived from seismic data and interval transit times from a calibrated normal geopressure trend. Pore pressure prediction is used to develop a 3d model for the pressure regime and it is a critical property towards an effective reservoir simulation and management. Pore pressure prediction has been a vital concern to the oil and gas industry for many decades. Pore pressure analysis mainly includes three aspects, that is, predrill pore pressure prediction, realtime pore pressure detection, and postwell analysis. The magnitude of the deviation from the normal trend line is used.
Based on the analysis in the study, the method by eaton is the most accurate. Pdf pore pressure prediction using geophysical methods. Velocity estimation for porepressure prediction aapg datapages. Pore pressure prediction and interpretation starts in the planning stage, with offset well information and seismic data used to develop predrill pressure estimates. 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. Changes in pore pressure can be recognized on regular formation evaluation tools such as sonic, resistivity, porosity, and density logs. Most petroleum provinces exhibit overpressures, and as the industry explores for deeper targets, encountering high overpressures is becoming more common.
However, a number of different compaction trends can be. Understanding pore pressure prediction in unconventional plays is important for executing a safe drilling strategy and for accurate production modeling. When the indicator suggests porosity values that are higher than the trend, then abnormal pressures are suspected to be present. For unconventional resources, pore pressure has also a significant impact on our ability to artificially fracture shale formations and to achieve successful completion. Uncertainty, realtime updating and how real time updating reduces uncertainty ahead of the bit. The calibrated model was then used to simulate and predict porepressure distribution in the pit walls for different time periods. Challenges in pore pressure prediction for unconventional. Pdf pore pressure prediction using wellconditioned.
Pore pressure prediction is required in order to carry out safe drilling and well completion job. Comparing methods of predicting pore pressure ijser. Seismic driven pore pressure prediction joanne wang. It is also possible to predict the relative number of casings. During drilling, realtime data as outlined in this chapter are then used to detect and assure all see pressure interpretation benefits can result. Calculate dexponent to predict pore pressure trends. Pdf abnormal pore pressure can cause some problems during the drilling process such as a blowout or sticking pipe while drilling. Schlumberger works with seam to improve predrill pore. 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. Pore pressure prediction using seismic velocity modeling. These logs show the effects of pore pressure because of the relationship between compaction, porosity, density. Pore pressure prediction using wellconditioned seismic velocities. P p is the formation pore pressure psi p p z is the normal pore pressure gradient psi ft1.
Calculating pore pressure in various types of formations. Todays topics ppp technology overview suitforpurpose seismic velocity analysis a workflow example ppp in 1d and 3d. Velocity field obtained using a conventional method based on the dix equation. The subsurface pore pressure buildup partitions are. The estimates are either used by geologists or mud engineers for safety by identifying the potential drilling hazards. The subsurface hydrogeological zoning greatly impacts the velocity, resistivity and density profiles. Pore pressure prediction is crucial to prepare a safe drilling program especially if the well will potentially intersect shallow gas zones. The significant growth of timelapse seismic surveys gives us a possibility to check the robustness and limitations of these classical prediction methods, and might also lead to new methods for pressure prediction that can be used in exploration. Pdf reliable prediction of pore pressure pp is critically important to petroleum engineering at different stages. Methodology used to derive the overburden gradient key parameter of terzaghi equation different techniques can be used according to well data available. A detailed description of pore pressure terminology can be found in bruce and bowers 2002, bowers 2002 and dutta 2002. Pore pressure prediction porosity stress mechanics. Seismic pore pressure prediction in the norwegian sea. Improve predrill pore pressure prediction in gom and other salt basins.
Simulation of threedimensional porepressure distribution. Pore pressure estimation is important for both exploration and drilling projects. Pore pressure prediction reduce uncertainty in pore pressure estimations. Seismic pore pressure prediction in the norwegian sea, halten terrace the halten terrace the study area is highlighted in green covering the halten terrace in the norwegian sea. Pore pressure prediction and modeling using seismic velocities. Pore pressure prediction is the ability to create numerical formulas that mimic the subsurface pressure profile. A quantitative predrill prediction of pore pressure is required when drilling in overpressured formations, and can be obtained. The model was calibrated against measured water levels, pore pressures, drains, and seepage rates. Pore pressure calculation in a hydraulicallyconnected formation is introduced. Pdf pore pressure prediction in a carbonate reservoir. Most methods for pressure prediction from seismic are based on detection of low velocity anomalies. 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 methods most methods of pore pressure predictions are based on terzaghis effective stress relation terzaghi, 1943 that expresses elastic wave velocity as a function of vertical effective stress. Razak damit5 1 australian school of petroleum, adelaide, australia 2 deeppp exploration technologg,ies crc, adelaide, australia. Formation pore pressure prediction is essential for executing a safe drilling program. During the well planning stage, reservoir pore pressure influences everything from the casing design to the mud weight and type selection.
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