Understanding borehole surveying accuracy

Jamieson, Angus L.

doi:10.1190/1.2148186

Cited by 1 publication

(1 citation statement)

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“…Geomagnetic referencing has made it possible in recent years to obtain accurate real-time directional survey data (Buchanan et al 2013). This improved well-survey accuracy has reduced subsurface position uncertainty for more recently drilled wells compared with those drilled historically with gyrotype survey tools (Jamieson 2005). However, survey data tend to involve more errors in the horizontal dimensions than vertical dimension and the accumulated position errors of about 1% of the total measured depth are not unusual.…”

Section: Ellipse Of Uncertainty (Eou) Distancementioning

confidence: 99%

Optimizing the separation factor along a directional well trajectory to minimize collision risk

Khosravanian¹,

Mansouri

Wood

et al. 2020

J Petrol Explor Prod Technol

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Optimizing the trajectory of directional wellbores is essential to minimize drilling costs and the impacts of potential drilling problems. It poses multi-objective optimization challenges. Well-design optimization models initially focus on wellborelength minimization, but ideally also need to consider minimizing the surface torque during drilling and address, among other constraints, collision avoidance with offset wells. A novel trajectory-optimization model is described that computes the separation factor along the wellbore. It employs a genetic optimization algorithm with an objective function that maximizes the minimum separation factor along the entire length of a wellbore. Plausible well trajectories are identified within a feasible solution space defined by user-identified constraints. The simplicity and effectiveness of the proposed model are demonstrated using a case study involving real well data from the Reshadat oil field offshore southern Iran. In the case considered, a proposed well trajectory is identified as unsafe in terms of its minimum separation factor with an offset well and is re-planned with the proposed model to achieve a safer trajectory.

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Section: Ellipse Of Uncertainty (Eou) Distancementioning

confidence: 99%