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Collaborating Authors
Well Drilling
Surge-and-Swab Pressure Predictions for Yield-Power-Law Drilling Fluids
Crespo, Freddy (University of Oklahoma) | Ahmed, Ramadan (University of Oklahoma) | Enfis, Majed (University of Oklahoma) | Saasen, Arild (Det norske oljeselskap and University of Stavanger) | Amani, Mahmood (Texas A&M University at Qatar)
Summary Surge and swab pressures have been known to cause formation fracture, lost circulation, and well-control problems. Accurate prediction of these pressures is crucially important in estimating the maximum tripping speeds to keep the wellbore pressure within specified limits of the pore and fracture pressures. It also plays a major role in running casings, particularly with narrow annular clearances. Existing surge/swab models are based on Bingham plastic (BP) and power-law (PL) fluid rheology models. However, in most cases, these models cannot adequately describe the flow behavior of drilling fluids. This paper presents a new steady-state model that can account for fluid and formation compressibility and pipe elasticity. For the closed-ended pipe, the model is cast into a simplified model to predict pressure surge in a more convenient way. The steady-state laminar-flow equation is solved for narrow slot geometry to approximate the flow in a concentric annulus with inner-pipe axial movement considering yield-PL (YPL) fluid. The YPL rheology model is usually preferred because it provides a better description of the flow behavior of most drilling fluids. The analytical solution yields accurate predictions, though not in convenient forms. Thus, a numerical scheme has been developed to obtain the solutions. After conducting an extensive parametric study, regression techniques were applied primarily to develop a simplified model (i.e., dimensionless correlation). The performance of the correlation has been tested by use of field and laboratory measurements. Comparisons of the model predictions with the measurements showed a satisfactory agreement. In most cases, the model makes better predictions in terms of closeness to the measurements because of the application of a more realistic rheology model. The correlation and model are useful for slimhole, deepwater, and extended-reach drilling applications.
- Europe (1.00)
- Asia (0.68)
- North America > United States > Texas (0.29)
- North America > United States > California (0.28)
- Research Report > Experimental Study (0.67)
- Research Report > New Finding (0.46)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Pressure Management > Well control (1.00)
- Well Drilling > Drilling Operations (1.00)
- (2 more...)
Abstract A significant cost issue is related to solids control ant the affiliated waste production during drilling. This cost issue includes the reduced drilling efficiency due to poor solids control when the drilling fluid temperature is low. The primary solids control device is the shale shakers. The preferred shakers have two or three decks that all separate particles from the drilling fluid. Especially when the temperature is low, the flow through the screens on these shakers is limited leading to a large discharge of drilling fluid along with the drilled cuttings. To increase the efficiency of the shakers a new header box is developed that change the direction of the drilling fluid entering the shakers top deck. On several North Sea operations this device has successfully been used to divert the flow onto the entire top deck screen. This made it possible to run the equipment with finer screens than usual; leading to operating with cleaner drilling fluids than usual and thereby faster drilling rate at the same time as the occupational hygiene in the shaker room was significantly improved. The paper describes in detail how the shakers were modified with the header box and how the shakers were run to optimise drilling performance even when the drilling fluid was cold.
- North America > United States > Texas (0.29)
- Europe > United Kingdom > North Sea (0.25)
- Europe > Norway > North Sea (0.25)
- (2 more...)
- Well Drilling > Drilling Fluids and Materials > Solids control (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
The Design of BHA and the Placement of Magnetometer Sensors Influence How Magnetic Azimuth Is Distorted by the Magnetic Properties of Drilling Fluids
Waag, Tor Inge (Teknova A/S) | Torkildsen, Torgeir (Wellpos A/S) | Amundsen, Per Amund (University of Stavanger) | Nyrnes, Erik (Statoil ASA) | Saasen, Arild (Det norske oljeselskap ASA and University of Stavanger)
Summary The magnetic property of drilling fluid is one of the substantial error sources for the determination of magnetic azimuth for wellbores. Weight material, cuttings, clay, and other formation material in addition to metal filings from tubular wear may distort the magnetometer readings. This effect is obviously linked to the amount and kind of magnetic material that is in the drilling fluid, and the development of corrective means has therefore highlighted the drilling fluid. The problem has been studied by laboratory experiments and analyses of downhole-survey data. However, there are several inconsistencies in the results, and the phenomenon is not understood fully. We focus on the geometric properties of the bottomhole assembly (BHA) and the magnetic directional tool in this study. The influence on directional measurement while drilling (MWD) from drilling fluids has been studied using finite-element modeling techniques. The simulations have been performed for several cases with realistic representations of MWD-tool geometries and varying location of BHA vs. the wellbore. One important result is that for situations with perfect axial symmetry, the magnetometer readings are attenuated proportionally to the square of the magnetic susceptibility. Because the magnetic susceptibility is a small number, the effect on magnetometer readings is generally negligible. However, if the symmetry is broken, the distortion on the magnetometer readings can be increased significantly. This means that segregation of cuttings, metal filings, or weight material can have a strong influence on the strength of the measured magnetic fields. With a collar-based tool that is asymmetric by nature, the model shows a complex distortion picture. The influence varies with the tool-face angle and shows both attenuation and amplification. The distortion maxima and minima for the two crosssectional magnetometers do not coincide. These findings underline how difficult it will be to find a straightforward corrective action. The results from the simulations give increased knowledge about the influence from the magnetic properties of the drilling fluid. This is essential for accuracy estimation and multistation analysis of magnetic-survey data. Furthermore, the results demonstrate the importance of considering the geometry of the BHA and the tool and of the sensor placement when performing the mechanical design.
- North America > United States (1.00)
- Europe > Norway (1.00)
- Well Drilling > Drilling Measurement, Data Acquisition and Automation > Measurement while drilling (0.91)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (0.68)
- Well Drilling > Well Planning > Trajectory design (0.66)
Borehole Instability in Tertiary Shales in the Norwegian North Sea
Nes, Olav-Magnar (SINTEF Petroleum Research) | Bøe, Reidar (SINTEF Petroleum Research) | Sønstebø, Eyvind F. (SINTEF Petroleum Research) | Gran, Kjetil (Det Norske oljeselskap ASA) | Wold, Sturla (Det Norske oljeselskap ASA) | Saasen, Arild (Det norske oljeselskap ASA and University of Stavanger) | Fjogstad, Arild (Baker Hughes AS)
Copyright 2012, Society of Petroleum Engineers This paper was prepared for presentation at the SPE Deepwater Drilling and Completions Conference held in Galveston, Texas, USA, 20-21 June 2012. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright. Abstract Severe hole stability problems were encountered in a recent exploration well in thee Norwegian North Sea. The problems occurred when drilling through Tertiary shale sections interbedded with permeable sand layers. Drilling was initially performed with water based drilling fluid. However, being unable to reach the section target after more than two weeks of operation, the section was plugged back and a sidetrack was drilled using ann oil based drilling fluid without encountering major operational problems. On the basis of the post-drill analysis of drilling data, well logs, drill cuttings and borehole cavings sampled from the well, this paper describes how the complex combination of drilling fluidd salt concentration and geological constraints may be utilized to ensure successful future drilling operations in this part of the North Sea. Cuttings and preserved cavings collected during the drilling operation were selected from several depth intervals identified as potentially troublesome from drilling experience and log data. Determination of cuttings mineralogy enabled better prediction of how the time dependency of the stable drilling fluid d density window is influenced by interaction between the shale and the drilling fluid. Mechanical strength is a key input parameter when predicting borehole stability. Dedicated rock mechanical punch measurements on cavings were used to confirm the prediction of strength from log data alone.
- Europe > United Kingdom (1.00)
- Europe > Norway > North Sea > Central North Sea (0.28)
- North America > United States > Texas > Galveston County > Galveston (0.24)
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.94)
- Europe > United Kingdom > North Sea > Central North Sea > Egersund Basin > PL 038 > Sleipner Formation (0.99)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Faroe-Shetland Basin > Rona Ridge > Block 206/9 > Clair Field (0.99)
- Europe > United Kingdom > Atlantic Margin > West of Shetland > Faroe-Shetland Basin > Rona Ridge > Block 206/8 > Clair Field (0.99)
- (26 more...)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- (2 more...)
The Design of BHA and the Placement of the Magnetometer Sensors Influence How Magnetic Azimuth is Distorted by the Magnetic Properties of Drilling Fluids
Waag, Tor Inge (Teknova AS) | Torkildsen, Torgeir (Wellpos AS) | Amundsen, Per Amund (University of Stavanger) | Nyrnes, Erik (Statoil ASA) | Saasen, Arild (Det Norske Oljeselskap ASA and University of Stavanger)
Abstract The magnetic property of the drilling fluid is one of the substantial error sources for the determination of magnetic azimuth for wellbores. Both the weight material, cuttings, clay and other formation material plus metal filings from the tubular wear may distort the magnetometer readings. This effect is obviously linked to the amount and kind of magnetic material in the drilling fluid, and the development of corrective means has therefore highlighted the drilling fluid. The problem has been studied by laboratory experiments and analyses of downhole survey data. However, there are several inconsistencies in the results, and the phenomenon is not fully understood. The geometric properties of the BHA and the magnetic directional tool are focused upon in this study. The influence on directional MWD from drilling fluids has been studied using finite element modeling techniques. The simulations have been performed for several cases with realistic representations of MWD tool geometries and varying location of BHA versus the wellbore. One important result is that for situations with perfect axial symmetry, the magnetometer readings are attenuated proportionally to the square of the magnetic susceptibility. Since the magnetic susceptibility is a small number, this means that the effect on magnetometer readings is generally negligible. However, if the symmetry is broken, the distortion on the magnetometer readings can be increased significantly. This means that segregation of cuttings, metal filings or weight material can strongly influence the strength of the measured magnetic fields. With a collar based tool, that is non-symmetric by nature, the model shows a complex distortion picture. The influence varies with the tool face angle, and shows both attenuation and amplification. The distortion maxima and minima for the two cross-sectional magnetometers do not coincide. These findings underline how hard it will be to find a straight-forward corrective action. The results from the simulations give increased knowledge about the influence from the magnetic properties of the drilling fluid. This is essential for accuracy estimation and multistation analysis of magnetic survey data. Furthermore, the results demonstrate the importance of considering the geometry of the BHA and the tool, and of the sensor placement when performing the mechanical design.
- Well Drilling > Drilling Measurement, Data Acquisition and Automation > Measurement while drilling (0.72)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (0.68)
- Well Drilling > Well Planning > Trajectory design (0.48)