Well-Test Analysis in Low-Permeability Multilateral Wells

This reference is for an abstract only. A full paper was not submitted for this conference. Multilateral horizontal wells are used extensively in a number of reservoirs around the world, and particularly in the Middle- East. Development is often based on patterns of multilateral producers and multilateral injectors, and these, combined with complex reservoir geology, create well test pressure behaviors that are usually difficult to interpret. Ideally, well tests should be conducted one individual horizontal branch at a time and branch rates and producing lengths should be measured in order to decrease the non-uniqueness of the well test interpretations. In practice, this is not often possible and all branches are tested together. Low permeability reservoirs add to the difficulty, by reducing the information available within the normal duration of a build-up test. Although theoretical solutions for multilateral wells have been published in the oil literature, there are very few actual examples of well tests and even fewer detailed well test analyses. This paper describes the analyses of well tests on several multilateral wells in a low permeability carbonate reservoir in the Middle-East. It is shown how a maximum of useful information can be extracted from the well test data, using a combination of techniques and tools, such as time-lapsed derivative analysis, analytical multiwell simulators, and deconvolution. Limitations and uncertainties in the analyses as a function of the data available are also discussed.