Correlations to determine in-situ stress from open-hole logging data in sandstone reservoirs

Abstract

Knowledge of in-situ stress distribution within reservoir sandstones and the surrounding formations is recognized as one of the most important factors in the design and analysis of hydraulic fractures. In-situ stress contrast between layers of rock ultimately controls the vertical fracture growth and, thus, directly affects fracture length and width. A new correlation model has been developed for estimating in-situ stress distribution within different interlayers. The method correlates values of minimum principal in-situ stress derived from both open-hole log data and cased-hole stress tests and gamma ray readings. The information used during this research project came from the Gas Research Institute (GRI's) Staged Field Experiment (SFE) No. I and No.2 wells. The new parameter correlation developed in this research has been applied to the Travis Peak Formation in East Texas. The advantages of the new correlation are (1) for a routine application, the correlations provide the most useful source of in-situ stress determination in the Travis Peak Formation, (2) the effect of shale has been considered in the correlation model, and (3) the model is easy to use once the lithology of the layer has been identified. This new model can be used to estimate in-situ stress distribution from logs and cores. However, it is important that these estimates be calibrated with actual field measurements of in-situ stress. Once the model correlation model has been calibrated, the petroleum engineer can reduce the cost of developing data sets for conducted reservoir studies by using only logs to estimate the in-situ stress profile.