TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper presents results of an underground gas storage modeling study using the reservoir and fluid properties of the Northern Marmara gas field, a recently developed field in the Thrace region of Turkey. It has an area of 3.6 km 2 with nearly 3 billion sm 3 of GIIP. The reservoir model used in this study is based on the theoretical as well as the empirical deliverability equations. The deliverability equations reflect the production and injection performances of the wells with given completion characteristics.Our approach is based on maximizing working gas volume for a particular configuration of reservoir, well and surface facilities. The importance of the type of well completion was emphasized in this paper because this is the most likely place for operating problems to occur. The deliverability performance strongly affects the design factors such as the working gas volume and the number of wells operated. Results indicate the performance dependence on wellbore damage and hence the importance of cleanup of wells.The effects of the mechanical skin factor on the working gas capacity with different number of horizontal wells as well as vertical ones were studied. Results show that the working gas capacity decreases while the mechanical skin factor increases. This behavior becomes especially more dramatic as the horizontal well length decreases. The increasing number of wells increases the working gas capacity as expected. These results are discussed in detail through application to N. Marmara gas reservoir data.The underground gas storage modelling approach followed in this study is shown to be an effective way to forecast the production / injection performance and to estimate the important design parameters when converting a depleted gas reservoir to a gas storage reservoir. Our approach yields the better understanding of the effect of the wellbore conditions on the performance of the underground gas storage reservoirs as well.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn this paper, new explicit analytical equations for stabilized and transient deliverability coefficients in terms of formation/fluid parameters are presented. These equations are derived for fully and partially penetrating vertical wells and for fully penetrating horizontal wells. The proposed equations use the relationship between the empirical (Rawlins and Schellhardt) deliverability equation and rigorous (or Forechheimer's) deliverability equations for both stabilized and unstabilized (transient) flow conditions. Based on these new equations, we also present new methods for determining not only the performance coefficients, but also formation parameters from stabilized and transient gas deliverability data. Unlike the existing methods, our new methods do not require geometric mean of pressure or rate data. This is a distinct advantage of the methods presented in this paper over the existing methods because determination of geometric mean of pressure or rate data may be quite difficult, and the mean value is quite sensitive to the measurement errors in such data. Thus, the methods given in this paper should prove very useful for determining formation parameters accurately from deliverability tests in vertical and horizontal wells. The accuracy and applicability of the methods given in this study are verified by analyzing two test data published previously in the literature. Results are compared with those obtained from the existing methods in the literature and indicate that combination of our new methods with the Hinchman-Kazemi-Poettmann method for isochronal test types provides more information about the formation and reliable deliverability forecasting.

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