Injection profiling in horizontal wells using temperature warmback analysis

Abstract

Horizontal wells have been used for water flooding operations for the purpose of pressure maintenance and improved oil recovery, e.g., in tight oil reservoirs. Injection profiling along the well lateral is required to determine the effectiveness of water flooding operations and to maintain high sweep efficiency. Recent improvements in downhole temperature monitoring tools allow monitoring the transient temperature along horizontal waterflooding wells at a relatively low cost. Temperature data can be analyzed to infer the injection profile along wellbore and locate high permeability regions that cause non-uniform rate distribution along the wellbore. In this work, an analytical model is developed to describe the transient temperature in the reservoir during cold fluid (water) injection via a horizontal well during injection and warmback periods. The analytical solution assumes linear flow in the reservoir and accounts for heat transfer by different mechanisms including convection, conduction, and heat gain from the surrounding impermeable strata. The inversion procedure is introduced to evaluate injection profiling using analytical solution-based type curves. Different cases are considered using a thermally coupled numerical reservoir simulator to verify the analytical approach and illustrate the potential application of the inversion technique. We show that the analytical approach introduced in this work is an efficient and robust technique to infer the injection profile along horizontal wells. Keywords Injection profiling . Horizontal wells . Temperature warmback analysis . Analytical modeling Abbreviations α t thermal diffusivity of reservoir, L 2 /t,ft 2 /s[m 2 /s] β dimensionless convection parameter BVP boundary value problem C r , C w , C s heat capacity of reservoir system, reservoir fluid, and solids, L 2 /(t 2 T), Btu/lbm F [J/kg K] DTS distributed temperature sensing D f hydraulic front position, L, ft [m] Erfc (−) complementary error function h reservoir thickness, L, ft [m]

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“…The direct measurement method utilizes the site drilling to directly measure the temperature, and determines the thermal reservoir temperature by calculating the average of the thermal reservoir top plate and bottom plate temperatures. However, in most cases, there is no drilling hole in the site or the depth of the drilling hole does not reach the geothermal reservoir, and at the same time, after the drilling of the final hole, the accuracy of the measured temperature varies greatly according to the time when the drilling hole has been stationary, so that direct measurement of the reservoir temperature by on-site drilling is a very expensive and time-consuming work 7 , 8 . Indirect calculation method, i.e.…”