Time lapse logging

In this chapter, we will present some basic ideas about borehole flow invasion and lost cireulation. Once the fundamentals are clearly explained, we will introduee a relatively new concept known as time lapse logging. We will begin our diseussion with the simplest invasion models and progress to those that bear inereasing sophistieation. Then, we will indicate how these results can be used to assist in formation evaluation and reservoir deseription, discuss possible pitfalls, and direet the reader to more recent literature. 

Chinetal. 19SdO NEUTRON INVASION DENSITY Figure 14-1. Time lapse logging, field results. 

This implies that time lapse logging ean be subjective, drawing upon field experienee. Log interpretation may direet the analyst to some of the fluid models in this book it becomes his job to understand how his tool responds with respect to the model and to interpret his readings based on environmental variables. Log analysts who deal with resistivity interpretation and tornado charts have criticized the defieieneies behind the modeling of resistivity... 

Holditch, S.A., and Dewan, J.T., The Evaluation of Formation Permeability Using Time Lapse Logging Measurements During and After Drilling, Annual Report, Contract No. 5089-260-1861, Gas Research Institute, Dec. 1991. 

Borehole Flow Invasion, Lost Circulation, and Time Lapse Logging, 235... 

Hydrocarbon-water contact movement in the reservoir may be determined from the open hole logs of new wells drilled after the beginning of production, or from a thermal decay time (TDT) log run in an existing cased production well. The TDT is able to differentiate between hydrocarbons and saline water by measuring the thermal decay time of neutrons pulsed into the formation from a source in the tool. By running the TDT tool in the same well at intervals of say one or two years (time lapse TDTs), the rate of movement of the hydrocarbon-water contact can be tracked. This is useful in determining the displacement in the reservoir, as well as the encroachment of an aquifer. 

Xue Z., Tanase D., et al. Estimation of C02 saturation from time-lapse C02 well logging in an onshore aquifer, Nagaoka, Japan. 2006 Journal of Exploration Geophysics 37 19-29. 

Muller N., RamakrishnanT.S., et al. Time-lapse carbon dioxide monitoring with pulsed neutron logging. 2007 International Journal of Greenhouse Gas Control 1 456-472. 

To be more precise, the general tensor equation of Newton s law of viscosity should be obeyed by a Newtonian fluid (2) however, for onedimensional flow, the applicability of eq 1 is sufficient. For a Newtonian fluid, a linear plot of t versus 7 gives a straight line whose slope gives the fluid viscosity. Also, a log-log plot of t versus 7 is linear with a slope of unity. Both types of plots are useful in characterizing a Newtonian fluid. For a Newtonian fluid, the viscosity is independent of both t and 7, and it may be a function of temperature, pressure, and composition. Moreover, the viscosity of a Newtonian fluid is not a function of the duration of shear nor of the time lapse between consecutive applications of shear stress (3). 

Analytical Methods for Time Lapse Well Logging Analysis 353... 

Doveton, J.H., 1986. Log Analysis of Subsurface Geology. John Wiley Sons, New York. Drury, M.J., Jessop, A.M., 1983. The estimation of rock thermal conductivity from mineral content— an assessment of techniques. Zbl. Geol. PaliionL Teil 1, 35-48. 1983 H 1/2. Duffaut, K., Landro, M., 2007. Vp/Vs ratio versus differential stress and rock consolidation a comparison between rock models and time-lapse AVO data. Geophysics 72 (5), C81-C94. Dunham, R.J., 1962. Classification of carbonate rocks according to depositional texture. In Ham, W.E. (Ed.), Classification of Carbonate Rocks—A Symposium. AAPG Memoirs, 1, American Association of Petroleum Geologists, Tulsa OK/USA, pp. 108-121. 

The ideal forest operation sees the lapse time between felling and milling reduced to a week at most. For somewhat longer periods limited protection can be provided by brushing or spraying the exposed end-grain of logs with a biocide such as copper-8 quinolinolate. 

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