MEASURED AND CALCULATED HORIZONTAL STRESSES IN THE TRAVIS PEAK FORMATION

This paper presents the results of an experimental program to determin e in-situ horizontal stress magnitudes from the dynamic mechanical pro perties of tight-gas sand cores. These measurements were made on 47 ve rtical plug samples from the Gas Research Inst. (GRI) test wells, Stag ed Field Experiment (SFE) Wells 1 through 3. The wells were cored in t he Travis Peak formation of east Texas from approximate to 6,500 to ap proximate to 9,500 ft deep. Vertical overburden stress gradient was me asured in one well using a downhole gravimeter. The core mechanical pr operties were used with the Anderson and Newberry equations to calcula te in-situ horizontal stress. Actual insitu minimum horizontal stress was determined from instantaneous shut-in pressures measured during mi nifracture and microfracture tests. The Newberry equation was found to give results that agreed best with measured horizontal stress. A clos er match was obtained between measured and calculated horizontal stres s values when we used dynamic Poisson's ratio from partially gas-satur ated samples. The assumptions and limitations of the procedure are pre sented.