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Summary We have derived model laws that relate experimental parameters of a physical model of hydraulic fracture propagation to the prototype parameters. Correct representation of elastic deformation, fluid friction, crack propagation, and fluid leakoff forms the basis of the scaling laws. For tests at in-situ stress, high fluid viscosity and low fracture toughness are required. Tests on cement blocks agreed with the scale laws based on elastic behavior.

Summary The wells in the Muldoon field, first drilled in 1952, produce from shallow, high-porosity, freshwater Eocene sands. Production may be either oil or gas. Vintage Petroleum Corp. purchased the field in June 1984 with the objective of reworking the existing wells and increasing field production through the selective plugging of zones and the opening of new zones currently behind casing. To accomplish this, it was necessary to determine oil/water contacts, water zones, and potential pay zones as yet unproduced. Serious obstacles to this objective were lack of adequate logs [most wells had only an electric log (ES) or induction electric log (IES)] and the very fresh formation waters (1,500 ppm chlorides). These obstacles were overcome through application of state-of-the-art "formation evaluation through casing." An induced gamma spectrometry log, compensated neutron log, and gamma ray log were used to evaluate the formations accurately and indicated not only oil/water contacts and watered-out zones, but also oil and gas zones. Because of the favorable production results, the structure has been re-evaluated and seven new well locations have been chosen. This paper will discuss the interpretation and results of the three wells that were initially evaluated and show how this re-evaluation has led to an increase in field production.