Prediction of Downhole Temperatures Can Be Key for Optimal Wellbore Design

Abstract

Prediction of Downhole Temperatures Can Be Key for Optimal Wellbore Design R.F. Mitchell; R.F. Mitchell Enertech Engineering and Research Co. Search for other works by this author on: This Site Google Scholar H.F. Wedelich, III H.F. Wedelich, III Enertech Computing Corp. Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Production Operations Symposium, Oklahoma City, Oklahoma, March 1989. Paper Number: SPE-18900-MS https://doi.org/10.2118/18900-MS Published: March 13 1989 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Mitchell, R.F., and H.F. Wedelich. "Prediction of Downhole Temperatures Can Be Key for Optimal Wellbore Design." Paper presented at the SPE Production Operations Symposium, Oklahoma City, Oklahoma, March 1989. doi: https://doi.org/10.2118/18900-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Oklahoma City Oil and Gas Symposium / Production and Operations Symposium Search Advanced Search AbstractThis paper describes an advanced method to predict downhole temperatures during operations. predict downhole temperatures during operations. Examples are presented that represent actual field cases and demonstrate the advantages of using the advanced method compared to conventional methods of estimating downhole temperatures.Two specific field cases are investigated in detail: Tubing movement during stimulation and well deliverability. In the stimulation case, comparison of the conventional and advanced methods in indicates that 35% fewer packer seals are needed in the specific well studied, and the thermal loads magnify the casing stresses by 25–35%. The well deliverability predictions show that a smaller size increases gas production for a constant pressure. pressure. The paper also presents the key engineering and computing features needed to aid engineers in evaluating and interpreting results predicted with the advanced method. Key variables are identified for the different applications. With the model variables can be controlled to optimize performance of well components and well operations.IntroductionWellbore Thermal simulation has long been recognized as an important tool for well design and well operations. The petroleum literature includes numerous wellbore thermal simulation papers on drilling, cementing, and circulation and on production/injection of single phase fluids. production/injection of single phase fluids. In the 1960's, steam stimulation provided the impetus for significant contribution in wellbore simulation. Predicted temperatures were needed for heat Predicted temperatures were needed for heat loss estimates, insulation design, and determination of casing thermal loads. In the 1970's, arctic operations generated another wave of wellbore thermal simulators. Flowing wellhead temperatures and permafrost thaw and freezeback estimates were needed for operational design.Most of the early models were limited to simple systems and steady-state or pseudo-transient temperature response. Predicted behavior at early times or under rapidly changing conditions was not accurate, and, hence, start-up and highly transient behavior such as during drilling, cementing, and injection could not be modelled. The permafrost models generally included fully transient heat transfer, but emphasized formation behavior at the expense of the wellbore, modelling only production or injection in simple wellbore geometries.In the 1980's, the need for wellbore simulation took a different twist. The push for deeper drilling both onshore and offshore, together with tighter controls on well costs, has changed our industry's viewpoint toward more reliable and cost effective design. We are no longer willing to accept overly conservative designs. Here, technology plays a key role, and wellbore simulation is a necessary tool for providing accurate information on operating providing accurate information on operating conditions. The objective is to determine the range of effects that unknown operating conditions have on flowing temperatures and pressures, and not assume that temperatures and pressures are the unknowns.With better estimates of downhole temperatures and pressures, well design and well operations can be improved. In cementing, accurate circulating and shut-in temperatures subject to a wide range of variables such as flow rate, hole size, and hole cleaning are needed for proper design of thickening time and wait-on-cement time. Drilling hydraulics is a function of rheology control which depends on downhole temperatures and pressures. Mud viscosity and, hence, friction losses and equivalent circulating densities are a strong function of temperature, particularly in oil base systems. Production heat particularly in oil base systems. Production heat losses affect wellhead temperatures and deliverability.P. 647 Keywords: heat transfer, circulation, reservoir surveillance, correlation, production logging, production control, injection, production monitoring, formulation, application Subjects: Well & Reservoir Surveillance and Monitoring, Production logging This content is only available via PDF. 1989. Society of Petroleum Engineers You can access this article if you purchase or spend a download.