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McSpadden A.R.,Altus Well Experts Inc. | Gunn A.,ConocoPhillips | Dunagan C.,ConocoPhillips
SPE/IADC Drilling Conference, Proceedings | Year: 2013

Wellbore temperature logs and associated field history data from an HPHT condensate North Sea platform are presented which validate the accuracy of a transient model of multiwell thermal interaction. The model is an updated version of previous work which simulates transient thermal interaction or "cross-heating" between closely spaced wells of a template. Multiwell thermal interaction alters final wellbore temperatures as well as formation temperatures in the inter-well zone and also further out from the well template. The multiwell thermal model is shown to converge closely in very characteristic fashion to two different logged and measured temperature profiles over a vertical depth range of 3000 ft. The empirical data including field history represents a unique opportunity to study and understand this important topic. Prior to this current work, industry discussion of multiwell thermal interaction or "cross-heating" has been largely anecdotal. Model validation against field data is necessary to achieve a full understanding of the physical system and to provide confidence in the predictive capability. Modeling of wellbore and formation temperatures for closely spaced wells has not been widely examined in the industry literature. The current work presents an improved methodology based on standard industry techniques. The method employs standard industry thermal-hydraulic modeling software and a fully transient finite-difference time-domain (FDTD) model in a loosely-coupled, iterative analysis. The iteration scheme is achieved by coupling of the standard analytical solution for the isolated single-well temperature scenario with the solution in the formation for the cross-heating scenario. The effect of multiwell thermal interaction is important for closely-spaced wells such as offshore platforms or subsea and arctic developments. The multiwell disturbance on formation and wellbore temperatures may affect well design, facilities planning and operations. Annular pressure build-up (APB), wellhead movement, tubular stress design, cement slurry design, subsidence/compaction effects and facilities health and safety issues can all be affected. If multiwell thermal interaction is not taken into account, then load events such as APB, wellhead movement and thermal induced stresses may be underestimated. Concurrent and batch drilling operations including cementation will also be affected. Copyright 2013, SPE/IADC Drilling Conference and Exhibition. Source


McSpadden A.R.,Altus Well Experts Inc. | Gunn A.,ConocoPhillips | Dunagan C.,ConocoPhillips
SPE Drilling and Completion | Year: 2013

Wellbore-temperature logs and associated field-history data from a high-pressure/high-temperature (HP/HT) condensate North Sea platform are presented that validate the accuracy of a transient model of the multiwell thermal interaction (MWTI). The model is an updated version of previous work by McSpadden and Coker (2010) that simulates transient thermal interaction or "cross heating" between closely spaced wells of a template. As discussed in the preceding work, the MWTI alters final wellbore temperatures as well as formation temperatures in the interwell zone and also farther out from the well template. The multiwell thermal model is shown to converge closely in very characteristic fashion to two different logged and measured temperature profiles at a vertical depth range of more than 3,000 ft. The empirical data, including field history, represent a unique opportunity to study and understand this important topic. Before this current work, the authors' experience found the industry discussion of the MWTI or "cross heating" to be largely anecdotal. Model validation against field data is necessary to achieve a full understanding of the physical system and to provide confidence in the predictive capability. The modeling of wellbore and formation temperatures for closely spaced wells has not been widely examined in the industry literature, as observed by Bellarby (2009). The current work presents an improved methodology on the basis of standard-industry techniques. The method uses standard industry thermal/hydraulic modeling software for a single well and a fully transient finite-difference model for the formation in a loosely coupled, iterative analysis. The iteration scheme is achieved by the coupling of the standard analytical solution for the isolated single-well temperature scenario with the solution in the formation for the cross-heating scenario. The effect of the MWTI is important for closely spaced wells such as offshore platforms or subsea and Arctic developments. The multiwell disturbance on formation and wellbore temperatures may affect well design, facilities planning, and operations. For example, given nominal flowing wellhead temperatures (FWHTs) approaching 350°F for HP/HT platform developments, even small temperature increases may have a critical impact on the design and layout of surface receiving systems. Annular-pressure buildup (APB), wellhead movement, tubular-stress design, cement-slurry design, subsidence/compaction effects, and facilities health and safety issues can all be affected. If the MWTI is not taken into account, then load events such as APB, wellhead movement, and thermally induced stresses may be underestimated. Concurrent- and batch-drilling operations, including cementation, will also be affected. Copyright © 2013 Society of Petroleum Engineers. Source


McSpadden A.R.,Altus Well Experts Inc. | Coker III O.D.,Altus Well Experts Inc. | Ruan G.C.,NOV CTES
SPE Drilling and Completion | Year: 2012

A purpose-built finite-element model (FEM) is applied to simulate radial displacement of a casing string constrained within an outer wellbore. The FEM represents a fully stiff-string model wherein the casing is approximated by general-beam elements with six degrees of freedom at each node to account for all possible physical displacements and rotations. Results predicted include deflection of the casing centerline from the wellbore centerline, effective dogleg curvature, bending deformation, wall-contact forces, and bendingstress magnification. These results will provide for a more-accurate assessment of well integrity in terms of casing-stress safety factors and centralization before cementing, as well as more accurate prediction of running loads during the drilling phase. In critical-well-casing design, accurate assumptions regarding bending stiffness may be necessary to avoid overly conservative as well as nonconservative analysis. Challenging finite high-pressure/high-temperature (HP/HT) and extreme-temperature wells are opportunities for increased design efficiency by avoiding overly conservative and costly designs, which can be crucial. Alternatively, design for extreme loads such as overpull loads in long deviated wells may be nonconservative if severe bending stresses are not considered. A realistic case study is presented that demonstrates the possibility to achieve cost efficiency by means of optimized casing design. A case study also is presented in which a nonconservative design may result if severe bending loads are not modeled. The purpose-built FEM code is in many ways preferable to the use of commercial finite-element-analysis (FEA) packages because of the time-consuming effort required to build up the detailed model. In typical casing and tubular-stress design, a soft-string model assumes casing strings are coincident with the wellbore centerline. The known or assumed wellbore curvature is applied directly to the casing string. Any effect of casing-string stiffness and allowable radial displacement within the outer wellbore is ignored. In many cases, this results in an overly conservative analysis. Likewise, the impact of bending-stress magnification is typically ignored, along with the effects of centralizer placement. This may also be nonconservative for critical overpull situations, such as in extended-reach-drilling (ERD) and horizontal wells. Copyright © 2012 Society of Petroleum Engineers. Source


McSpadden A.R.,Altus Well Experts Inc. | Trevisan R.,Altus Well Experts Inc.
SPE/IADC Drilling Conference, Proceedings | Year: 2016

In horizontal and extended reach wells where long completions are run into highly deviated or lateral zones, large compression loads arise due to running friction. These loads remain locked in the string when the packer or cement sets. Dissipation of friction during life service due to string vibrations and movements redistributes these friction loads between the wellhead and packer or top of cement. A numerical approach is presented to calculate the redistributed friction load so that an accurate initial tubing load is implemented in the tubular stress analysis. The proposed methodology offers an opportunity for design optimization via accurate prediction of tubing loads when the locked-in friction loads may be a determining factor in the balance between marginal tension limits near surface and marginal compression loads downhole. The numerical approach is a simple 1D finite element model in which incremental frictional loads are decomposed and redistributed based on relative stiffness of the string uphole and downhole of each local node. Essentially each portion of the string is represented as a series spring. The methodology requires input of the estimated friction load for each incremental element during running from a standard torque-drag analysis. The results are particularly relevant for ERD, multistage completion and shale-type multizonal lateral wells, where overestimation of in-service compression above the packer or cement may pose considerable design challenges for tubular components including connections. The common assumption to ignore friction in tubing analysis is non-conservative in that it may underestimate friction loads, especially downhole at the packer. However, applying the full slackoff load downhole is also unrealistic and overestimates compression above the packer leading to costly component selection. Results from the numerical model wherein post-dissipation friction loads are redistributed show that only a part of the friction induced compression migrates to the packer. Some of the redistributed friction load results in additional tension at the wellhead. The type of trajectory, kick off depth and deviation angle are important factors for the load redistribution. The methodology presented in this work provides an approach to calculate the proportion of friction load transferred to the surface compared to the packer or cement top. The redistributed result which divides the running friction load between hanger tension and downhole compression is not always. Copyright 2016, IADC/SPE Drilling Conference and Exhibition intuitive. Source


McSpadden A.R.,Altus Well Experts Inc. | Coker III O.D.,Altus Well Experts Inc.
SPE Drilling and Completion | Year: 2010

A method is presented to predict wellbore and formation temperatures for a template of closely spaced wells. Multiwell thermal interaction will alter the wellbore temperatures as well as formation temperatures in the interwell zones and also farther out from the well template. The change in temperature profile relative to a single well can be significant. For producing wells in close proximity, wellbore and formation temperatures will converge to a significantly hotter condition than in the isolated-single-well case. The modeling of wellbore and formation temperatures for closely spaced wells has not been widely examined to date. This problem has been approached only by using theoretical formulations based on simplified assumptions. The current work presents for the first time a methodology based on standard industry tools and models that yield results consistent with field experience. The method employs standard industry thermal/hydraulic-modeling software and a finite-element model (FEM) in a loosely coupled, iterative analysis that assumes steady-state conditions. Other numerical approaches including finite-difference (FD) and boundary-element- method (BEM) techniques are also considered. The far-field thermal-flux behavior of a single well is also considered as an important baseline for comparison. The effect of multiwell thermal interaction is important for closely spaced wells such as offshore platforms or subsea and Arctic developments. A case study is presented for a high-pressure/high-temperature offshore field development. The multiwell disturbance on formation and wellbore temperatures affects well design, facilities planning, and operations. Annular-pressure buildup, wellhead movement, tubular-stress design, cement-slurry design, subsidence/compaction effects, and facilities health and safety issues can all be affected. In some cases, unexpectedly high wellbore temperatures can be catastrophic. If multiwell thermal interaction is not taken into account, then load events such as annular-pressure buildup, wellhead movement, and thermal-induced stresses may be underestimated. For high-rate production wells, the increase in produced-fluid temperatures may be small, but even a small change may be critical. In all cases, the effect on outer wellbore strings/annuli and on the formation is significant. This also impacts the planning of offshore fields to be developed in phases with batch drilling. Copyright © 2010 Society of Petroleum Engineers. Source

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