The technological approach to well testing of prospecting and exploratory wells in the casing in the flowing mode has been well studied and is technically simple to implement. However, in case of non-overflowing flow regime well the testing process become significantly complicated and requires the involvement of a larger number of technical means. The «gas lift + level build-up curve (LBC) / inflow curve» method assumes the initial inflow stimulation by nitriding / swabbing, test for on pseudo-steady filtration modes (during gas lift), followed by tracing the level build-up curve. This method is primarily considered as a tool for obtaining a minimum set of parameters, such as the type of formation fluid and the volumetric flow rate. However, well testing of non-overflowing marginal formations using this method has a number of significant disadvantages, consisting in the limitedness of the obtained hydrodynamic characteristics of the object under study. First of all, this concerns the quality of the assessment of such key parameters as reservoir pressure, permeability of the remote formation zone and the state of the bottomhole formation zone. The main reason for the limitations of the LBC method is the long-term dominance of the effects of the wellbore storage, since at a low flow rate (5–10 m3/day) of oil or formation water, the pressure change depends only on the changing level in the well, according to the dynamics of which, it is often impossible to identify the response of the formation. The currently available approaches to the interpretation of the LBC do not give a conclusive assessment, due to the fact that when performing key stages of processing, a priori knowledge of the reservoir pressure parameter is required, the iterative selection of which can lead to significant errors in the results.
The approach to well testing given in the article by the inflow performance relationship curve + pressure build-up curve, implemented by means of a hydraulic jet pump arrangement, makes it possible to neutralize the complicating effects of the wellbore storage. In this paper, the authors highlight the results of comparing the quality assessment of well tests when testing low-flow oil-saturated reservoirs with a non-overflow inflow using the "Swabbing + LBC", as well as of the tests with the usage of jet pump assemblies. The article presents the key technological aspects of testing with the emphasis on the advantages and disadvantages of both methods.
References
1. Kremenetskiy M.I., Ipatov A.I., Gulyaev D.N., Otsenki produktivnykh svoystv plasta i skvazhiny po gidrodinamicheskim issledovaniyam (Estimates of the productive properties of the formation and wells based on hydrodynamic studies), Moscow: Publ. of Gubkin University, 2003, 86 p.
2. Houzé O., Viturat D., Fjaere O.S., The theory and practice of pressure transient and production analysis & The use of data from permanent downhole gauges, URL: https://www.kappaeng.com/documents/flip/dda51001/files/ assets/basic-html/page-1.html
3. Zeyn Al'-Abidin M.D., Sovershenstvovanie metodov interpretatsii dannykh gidrodinamicheskikh issledovaniy skvazhin s gorizontal'nym okonchaniem (Improvement of methods for interpretation of hydrodynamic test data of wells with horizontal completion): thesis of candidate of technical science, Tyumen, 2017.
