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dc.contributor.advisorSangesland, Sigbjørn
dc.contributor.advisorBerchan, Bjorn
dc.contributor.authorMuhammadali, Shaine
dc.date.accessioned2017-08-15T14:00:58Z
dc.date.available2017-08-15T14:00:58Z
dc.date.created2017-06-12
dc.date.issued2017
dc.identifierntnudaim:16909
dc.identifier.urihttp://hdl.handle.net/11250/2450808
dc.description.abstractDrilling in Barents Sea and North Sea proves to be an extremely difficult task, as these regions are situated in auroral zones having higher latitude, where, magnetic interference develop from magnetic field, magnetic storms and magnetic materials inside subsurface are quite common. For these regions, monitoring of magnetic field is utterly significant as any fluctuations can distort the tool sensor performance. This information is obtained through the space weather forecast, which provides data related to Sun and interplanetary space and is recorded from any onshore variometer station. However, for the Barents Sea the major drawback is this onshore variometer stations as they are situated approximately 400 km away from the rig-site, therefore, the error analysis for this zone needs some special consideration. The study revolves around the Relief Well that is created to protect the unwanted flow of oil and gas up to the surface from the Targeted Well. The well is planned to be 700 km away from the Targeted Well and is oriented in the North direction, with very small changes in azimuth. The main aim on the other hand, is to create a model along with the specific tool, and then try to estimate the Ellipses of Uncertainty (EOU) for both wells. Finally, a comparison study is also performed between the industry standard model and the self-made model. The total Measured Depth for the Relief Well is 1400 mMD, while for the Targeted Well it is 2354 mMD. However, the depth of interest for the Targeted Well is 690 mMD which is assumed to be the intersection location. The struggle begins by importing the new tool developed in COMPASSTM to try and observe the EOU dimension for both wells. For the Relief Well, the Semi Major Axis length at the final depth of 1400 mMD is 19.69 m, while for the Targeted Well it is 2.34 m. The next step is to individually assess and determine each error term contribution in the total length. This is done by removing all the error terms from the IPM file except the one that needs to be assessed. It is observed that Declination contributes 90.7% in total in Semi Major Axis length, while remaining 9.3% are from other errors. This same idea is also implemented to the self-made model. However, for the model an extensive study was performed for each error term to determine the individual contribution. Before the start of ellipse analysis, two separate studies are performed that relates to Temperature and Drill String Interferences (DSI). Temperature analysis is perform as a Quality Control (QC) check, ensuring that the MWD tool is reliable at that depth. Since the study is based on shallow formation, it is discovered that the BHA will not suffer any changes in length and MWD tool will operate in the designated range. However, this analysis is important for the HTHP wells, which might suffer an alteration in BHA length and will distort MWD sensor measurements. A second analysis is done relating to DSI. The BHA is divided into three regions, and the higher interference region is determined. Out of all, Region 1 that comprises of Bit is considered to be the highest Interference region, which is responsible for a severe distortion in MWD sensor. To combat this effect, the physical distance between the Bit and MWD sensor is increase by using the appropriate NMDC After the entire QC s check, the total Semi Major Axis size is evaluated from the model which is approximately 19.02 m. However, in the model, error terms such as Declination, DIP Angle and Total Magnetic Field (TMF) which are the strong functions of Geomagnetic Field of the area of interest contribute heavily in uncertainty. It is also perceived that a major of 30% error deviation exists between the two models; on the contrary, at the depth of interest, there is less than 5% deviation in ellipse dimension. Apart from ellipse dimension calculations, a comparison analysis is also executed related to probability of intersection at the plan location. It is observed that, from both models a probability of 0.039 which indicates one strike in every 25 attempts is obtained. For this analysis, the center to center distance and radii of the Targeted Well and Relief Well are necessary. From COMPASSTM a 14.6 m center to center distance along with the Separation Factor of 0.33 is retrieve from Anti-Collision Report, while from the model they are 14.76 m and 0.35 calculated. Furthermore, two distinguished studies are also performed in order to reduce the uncertainty ellipse dimension. In the first case, the numbers of survey stations are decrease from 38 to 26. It is figure out that, the ellipse size increases from 19.02 to 21 m after the reduction in survey stations. It is because of the decline in tool performance, while in the second study KOP is change from 505 m initially to 645 m, keeping the number of stations constant at 26. A drastic reduction is observed in ellipse dimension from 21 m to 15 m. Overall, the model involves an extensive computation, which comprises of some deficiencies that needs to be assessed in future in order to make it more feasible and functional
dc.languageeng
dc.publisherNTNU
dc.subjectPetroleum Engineering, Drilling Engineering
dc.titleError and Ellipses of Uncertainty Analysis in Far North
dc.typeMaster thesis


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