Production Logging as an Integral Part of Horizontal Well Transient Pressure Test (includes associated papers 28275 and 28928 )

Abstract

Abstract With the recent Surge in horizontal welldrilling, increased attention has been placed on assessing horizontal well productivity and the optimization of completion design. Transient pressure analysis has long been the standard for vertical well productivity measurement and evaluation. The complex geometry associated with horizontal wells makes transient pressure analysis quite difficult and also challenging. Recent technical developments have shown that combining drawdown and buildup tests, with downhole transient flow rate measurements can significantly enhance the quality of interpretation. However, uncertainty in the production interval and the associated production profile within the horizontal section can make the interpretation of these tests challenging and at times can result in nonunique answers. This may cause the interpreter to estimate a low well productivity and thus elevate the chances of premature well abandonment. The paper first discusses horizontal well transient pressure analysis methodology and then illustrates the development of a technique that can incorporate the production interval and production profile data. The proposed technique can be applied to specialized plots as well as to type curve and history matching methods. The technique can also optimize welltest design by forward modeling. Using the technique to optimize test design and to enhance the interpretation answers is illustrated via an actual field example. Introduction The number of horizontal wells projected to be drilled this year is more than double that was drilled last year and about eight times that of the year before last. This surge in horizontal well drilling for increased well productivity has brought attention to assessing the wellproductivity and completion design optimization of these wells. The pressure transient test has long been the standard in characterizing the vertical well formation-reservoir system(wellbore geometry, outer reservoir boundaries, faults, fractures, partial penetration, drive mechanism, etc.) and estimation of its flow parameters (permeability, reservoir pressure and skin factor). The complex geometry associated with horizontal wells can make pressure transient analysis difficult and challenging. Such a test, however, rewards us with additional reservoir flow parameters that are needed to adequately characterize the formation, but requires more parameters to adequately quantify well performance. The first two response models of pressure transient behavior of horizontal wells were presented concurrently by Goode and Thambynayagam and Daviau et al. In addition to the identification of the two radial flow regimes by Daviau et al., Goode and Thambynayagam identified an intermediate time linear flow regime. Since then the literature on this subject has considerably expanded to include more response modeling, test interpretation methodology by Kuchuk et al. and Joseph et al., and field applications by Kuchuk et al. and Shah et al. P. 355^