3D Model for Rock Strength and In-Situ Stresses in the Khuff Formation of Ghawar Field, Methodologies and Applications

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractKnowledge of geomechanical attributes has positive merits for drilling in hydrocarbon formations. In the Ghawar field, the Khuff is a deep, carbonate gas-bearing formation. Several development wells have been drilled into this formation and conventional logging data was acquired in them. Such data has been exploited in generating geomechanical attributes along the Khuff formation in those wells. Furthermore, hard data like minifrac tests and core mechanical properties was available in some of the wells and utilized in calibrating and validating the computed geomechanical properties.A study was conducted to develop a 3-dimensional characterization of geomechanical attributes in the Hawiyah-Khuff formation of the Ghawar field. The study was performed to provide a model that, together with existing geologic models, can be used to predict regions of drilling difficulty, provide guidance in selecting drilling bits, and help in designing drilling mud and optimizing hydraulic fracturing jobs in the field. The study established correlations between the geomechanical and the geological attributes in Hawiyah-Khuff wells. Then, these correlations were used with a preexisting Hawiyah-Khuff geocellular model to map the geomechanical attributes away from the wells in the 3D Hawiyah-Khuff space. Rock strength, minimum and maximum horizontal stresses are among the properties that were mapped, for the first time, in the 3D Khuff horizon.The 3-D geomechanical model is consistent with observed trends in drilling difficulty, and with the requirements for hydraulic fracturing within the Khuff horizons. The model has been used in assessing the borehole stability of deviated wells planned for the field. We present some illustrations and example applications in the paper.

A simulation study of hydraulic fracturing design in carbonate reservoirs: a middle east oilfield case study

“…Which does not consider the characteristics of the actual reservoir, nor does it consider the influence of different formation properties on the prediction of shear wave time difference. Therefore, rock mechanics calculation based on shear wave prediction obtained by empirical method tends to lead to unreasonable subsequent parameters (Al-Ruwaili and Chardac, 2003). This study fully considers the geological characteristics, takes the wells with S-wave as the template, and predicts the S-wave data of other wells through a multi-factor neural network.…”