Enabling Efficient Permanent Production Monitoring of Advanced Well Completions in Saudi Arabia Using Fiber Optic Distributed Temperature Sensing

Abstract

Although the recent focus in the industry on maximum reservoir contact (MRC) and Advanced well completions has provided significant improvements in reservoir depletion it has caused some data gathering disruptions for companies operating these wells. In particular, the options to perform well logging are much reduced, and the costs of performing a production log are extremely high. This is related to both the costs of the more advanced horizontal well logging tools and the more expensive logging methods, such as coiled tubing and tracker systems, used for the conveyance of these tools into the wellbore. In an effort to acquire high quality downhole data in a timely manner in MRC wells, Saudi Aramco set about investigating the alternatives to traditional production logging methods. A technology gaining greater industry acceptance in recent years is permanently installed Distributed Temperature Sensing (DTS) and this became the focus of investigation. The limitations of conventional DTS technology was, however, soon realized; In particular the limited temperature resolution offered was not sufficient for evaluating high angle maximum reservoir contact intelligent wells. At the time of investigation a new generation of DTS technology became commercially available, providing a 10-fold improvement in measurement resolution. This allowed Saudi Aramco to proceed with field trials of the technology. This paper will present the requirements for advanced DTS technology to provide quality data sets for use in rate and density modeling in highly deviated MRC wells. In addition, the installation of the downhole hardware in an advanced well completion and the data from the field trials will be presented. Background Over the past six years, Saudi Aramco has pioneered the use of Smart and Intelligent well systems in its MRC wells to reduce development costs and prolong unwanted water production and control early gas breakthrough. Saudi Aramco's original maximum reservoir contract (MRC) wells included openhole laterals drilled from a 7" completion liner to provide the required contact/reservoir foot print to optimize rate and recovery 1. More recent designs have utilized smart well completion technology in the 7" cased mother-bore to control inflow from each lateral to extend well life and increase recovery (as seen in Figure 1). In the event of water/gas break through in any lateral, the downhole valves are remotely operated from the surface through hydraulic and instrument lines run outside the production tubing.

Novel Analytical Methods of Temperature Interpretation in Horizontal Wells

“…It can be seen that only a small temperature change is recorded during such a low flow rate test. However, modern temperature measuring devices have sufficient resolution 40 to recognise such small temperature changes. Note, that in this case the ratio of temperature change with respect to gauge resolution is the parameter that will determine whether the gauge is suitable 38 .…”

“…Our analysis uses derivatives, hence static errors (accuracy) are unimportant and device resolution will determine whether a particular gauge is suitable for this purpose. The resolutions have been reported to be as low as 0.01 o C for DTS 40 and 0.005 o C for PDG. Note that the nature of the gauges is such that the estimation error can further be deceased by increasing the amount of data measured (this is possible since our preferred analysis time is predicted to be hours or days).…”

Combining Distributed Temperature Sensing With Inflow Control Devices – Provides Improved Injection Profile With Real-Time Measurement in Power Water Injector Wells

“…Although previous systems have been run above the production packer, in cased multilateral wells, and in open hole ICD production wells 1,2 , this was the first attempt worldwide to deploy a DTS system in an injection well with open hole completion across a passive ICD system. Although previous systems have been run above the production packer, in cased multilateral wells, and in open hole ICD production wells 1,2 , this was the first attempt worldwide to deploy a DTS system in an injection well with open hole completion across a passive ICD system.…”

Early-time Asymptotic, Analytical Temperature Solution for Linear Non-adiabatic Flow of a Slightly Compressible Fluid in a Porous Layer

“…These new data sets have required the development of new workflows and analysis methods for their physical interpretation. Many publications have described temperature sensing and its phenomenological interpretation Fryer et al 2005;Hembling et al 2008;Johnson et al 2006;Lee 2006); but few attempts have been made to develop a comprehensive, mathematical basis for the analysis of downhole temperature behavior of flowing wells (as defined by the reservoir heat transfer processes) that can be executed rapidly (Valiullin et al 2010(Valiullin et al , 2009Zhu et al 2008). Wellbore heat transfer calculations, on the other hand, have been extensively analysed (Muradov and Davies 2008;Ramey 1962;Yoshioka et al 2005).…”