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The new approach will provide a single and useful tool for estimating gas/condensate well productivity. The productivity of gas and oil well plays an important role in gas and oil field development, particularly gas Introduction condensate well that is characterised by severe loss of well deliverability due to liquid drop out below the dew Evaluation of well productivity is necessary for the point, and for establishing field proration schedules planning and development of gas/condensate reservoirs, and setting maximum allowable production rates for and for establishing field proration schedules and individual wells by regulatory agencies. Houpeurt setting maximum allowable production rates for wells equation and Rawlins-Schellhardt equation are the under specific reservoir conditions. In the natural gas most widely used gas deliverability equations by industry, engineers mostly used the Rawlins-engineers. Although the Houpeurt equation has a Schellhardt equation and Houpeurt to estimate the theoretical basis and is rigorously correct, the equation production capabilities of gas wells. The standard dry assumes that Darcy's law is still valid under high gas flow equations based on flow-after-flow, isochronal velocity of gas flow and that an additional term must be and modified isochronal testing have also been used to added to account for the increased pressure drop. The analyze the gas condensate well productivity when the Rawlins-Schellhardt equation still continues to be used retrograde condensate is viewed immobile at reservoir by the natural gas industry, however it was empirically conditions. Rawlings and Schellhardt (1936) put formulated and the deliverability plot is traditionally forward the empirical equation (1) after they observed reversed in order to estimate the deliverability that a log-log plot of the difference between the squares exponent.
Early estimates of gas well performance were conducted by opening the well to the atmosphere and then measuring the flow rate. Such "open flow" practices were wasteful of gas, sometimes dangerous to personnel and equipment, and possibly damaging to the reservoir. They also provided limited information to estimate productive capacity under varying flow conditions. The idea, however, did leave the industry with the concept of absolute open flow (AOF). AOF is a common indicator of well productivity and refers to the maximum rate at which a well could flow against a theoretical atmospheric backpressure at the reservoir. The productivity of a gas well is determined with deliverability testing.
A single-point test for gas well deliverability is an attempt to overcome the limitation of long test times required for flow-after-flow tests. Both the Rawlins and Schellhardt and Houpeurt analysis techniques are presented in terms of pseudopressures. A single-point test is conducted by flowing the well at a single rate until the sandface pressure is stabilized. One limitation of this test is that it requires prior knowledge of the well's deliverability behavior, either from previous well tests or possibly from correlations with other wells producing in the same field under similar conditions. Ensure that the well has flowed long enough to be out of wellbore storage and in the boundary-dominated or stabilized flow regime.
Abstract A method for analyzing transient flow-after-flow (FAF) deliverability test data from both gas and oil wells is presented. The paper describes the derivation and application of this method to several field and synthetic cases. The method solves the transient absolute open flow potential (AOFP) and average reservoir pressure (p) by evaluating the parameters of the Forchheimer (a and b) and the empirical backpressure (C and n) equations together with p. Consequently, this new method allows one to describe the stabilized deliverability equation from transient test data, given reasonable estimates of the reservoir drainage area and shape. This approach is a significant improvement over currently available methods, which require an independent, a priori knowledge of p for establishing a well's AOFP, along with the need to conduct a stabilized flow segment of the test. All the resulting formulations are flexible enough to handle the pressure, pressure-squared, and pseudopressure approach for gas wells. This methodology is not restricted to gas wells as oil wells also lend themselves to the proposed analysis procedures. For oil wells, we used the pressure approach for single-phase flow and the pressure-squared approach for two-phase flow. In the proposed technique, a well's orientation is unimportant. For example, a horizontal well's deliverability may also be characterized using the new method. In addition, layered reservoirs may be analyzed with the proposed technique. We also show that this method can be extended to injection wells. Synthetic data were initially used to verify the method. Field data from several gas and oil wells, including a horizontal well and gas injector, were then used to demonstrate the method's application. In all cases, the new method shows good agreement with the results obtained from conventional methods, both in terms of AOFP and p. Introduction Gas well deliverability testing traces its origin to the work of Rawlins and Schellhardt in 1936. This work presented the well-known empirical backpressure equation for analyzing conventional flow-after-flow test data. Further work showed that this equation could also be used to analyze isochronal and modified-isochronal data. P. 379