~ummary. Th~s paper cov.ers the e~ol~tion, full-sc:ue m~el study, an~ field application of gelled packer fluids for paraffin control III naturally ~owlllg wells. FIeld applIcatIOn of these Illsulatlllg p~cker flUIds has resulted in significant increases in the flowing tubing temperature III the seven wells treated to date. The temperature Illcreases from gelled-packer-fluid application alone have eliminated paraffin problems previously controlled with repeated hot-oil treatments. Before this application, chemical inhibition attempts were unsuccessful.The gell~ ~uid currently used is bas~ on a phosphate ester and sodium aluminate reaction that produces an aluminum phosphate ester aSSOCIatIOn polymer. The gellant IS commonly used in oil-based fracturing fluids.

This paper reports on the design and execution of a field experiment on recovery of heavy oils by steamdrive enhanced by additives. The goal of this project was to study the effect of injection of a commercial surfactant (Suntech IVTM) and N2 on the behavior of a conventional steamdrive. Because the laboratory studies leading to the design and implementation of this field experiment have been referenced many times, we emphasize here the field data obtained in reservoir definition, monitoring of the experiment's progress, and production evaluation in a heavy-oil reservoir. Several standard and experimental analytical methods were applied, and their validity in the Kern River field test is discussed.Three slugs of surfactant and N 2 were injected at different rates. Analysis of the results shows a considerable improvement in oil recovery by steamdrive caused by the addition of surfactant and N2 to the steam. The changes in production behavior of the reservoir caused by the additives are analyzed and discussed. Although the economics of this project is difficult to determine at this point, it looks promising.

SPE Members Abstract A case history is presented for a 160-acre-five-spot interference test performed in the Wahoo formation, a fractured carbonate within the Lisburne reservoir located at the North Slope of Alaska. Several results are realized from this test. First, the Lisburne reservoir is a heterogeneous formation with the possibility for dual porosity and multi-layered behavior. possibility for dual porosity and multi-layered behavior. Second, interference pressure data from two of the four observation wells can be analyzed utilizing a modified approach to the conventional anisotropic permeability technique. Third, even with considerable pretest planning and design, the reservoir responded differently than expected. The Lisburne Interference Test preceded field startup in an effort to determine directional permeability and to evaluate vertical and lateral continuity within the reservoir with a minimum amount of offset interference. The center well was cycled through a drawdown and build up while the four corner wells monitored pressure. Bottomhole pressure recorders were installed in the pressure. Bottomhole pressure recorders were installed in the wellbores prior to the start of the test. During the interference test, the observed pressure responses in the observation wells were significantly more rapid and of a greater magnitude than expected. Concurrent pressure transient analysis of the data, made possible by surface readout equipment, resulted in a shorter, less expensive test. The test analysis provided effective reservoir permeability from dual porosity type curve matching and semi-log analysis of the active well data with good agreement between the drawdown and build up results. Analysis of the observation well pressure data was consistent with the active well data and was achieved using dual porosity transient interporosity flow type curves and semi-log analysis. Because of reservoir heterogenities, the pressure data from only two of the four observation wells were analyzable with the conventional anisotropic permeability analysis method. Generally this method requires pressure data from three uniquely-oriented observation wells to obtain a solution. However, the anisotropic permeability model can place limits on the feasible solutions using data from only two wells, and with the elimination of one of the four unknown values through core data, a complete solution of the Lisburne Interference Test was achieved. Introduction The Lisburne reservoir is located within the Lisburne Participating Area of the Prudhoe Bay Unit on the North Slope of Participating Area of the Prudhoe Bay Unit on the North Slope of Alaska, as shown in Fig. 1. Discovered in 1968 during the drilling of Prudhoe Bay State No. 1, development of the Lisburne oil accumulation was deferred until early 1984 with field startup in late 1986. Because of the complexity of this carbonate reservoir, a five month Lisburne Interference Test (LIT) was planned for completion prior to field startup to further evaluate the reservoir for future development planning. The objectives of the test included quantifying the areal permeability and continuity within the pattern area and to evaluate the degree of reservoir anisotropy. The test was designed using the anisotropic form of the exponential integral solution to the diffusivity equation, since the Lisburne reservoir would likely exhibit anisotropic behavior. Likewise, it was intended to incorporate the anisotropic interference test models for the LIT analysis. However, the interference analysis, following the LIT, proved to be less than straightforward when only two of the four observation wells could be analyzed using the dual porosity model, due to reservoir heterogeneities. This data limitation resulted in the development of a modified approach to the conventional interference model in order to achieve a complete analytical solution, as presented in the following sections. INTERPRETATION THEORY Interference analysis is a pressure transient technique which provides information about the formation encompassing the provides information about the formation encompassing the active and observation wells. Since the pressure measurements are made in a non-producing well, the impact of skin and storage at both the active and observing wells are minimized and negligible for the LIT. P. 303

The deliverability of liquid-dominated geothermal reservoirs is presented in terms of reservoir performance, inflow performance, and wellbore performance. Water influx modeling is used to match the performance of Wairakei in New Zealand, and Ahuachapan in El Salvador. The inflow performance is given in terms of a linear productivity index for liquid-only flow, and a solution-gas drive relationship for two-phase flow. A 9-5/8 in. production well is assumed, flowing 250°C water from 900 m depth, and with a wellhead pressure of 100 psia. A geothermal development model that couples reservoir deliverability and power plant performance is used to illustrate how the development cost of geothermal electric power projects can be estimated.

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