Real-time method for maintaining formation stability and monitoring fluid-formation interaction

A method employing well service fluid for servicing a wellbore penetrating a subterranean formation said method comprising real-time monitoring of the stability of said wellbore using a wellbore stability model during said servicing of said wellbore, said method further comprising:

• (a) obtaining preliminary values for weight and chemical composition of said well service fluid using said wellbore stability model;
• (b) measuring acoustic, sonic, electrical, thermal and transient pressure responses of the formation;
• (c) calibrating said wellbore stability model with said measurements;
• and
• (d) obtaining values for the weight and chemical composition of said well service fluid using said calibrated wellbore stability model.

A method for maintaining stability of a wellbore penetrating a subterranean formation during drilling or well servicing operations, or during production or enhanced recovery operations, using fluids introduced into said wellbore to facilitate said operations, said method comprising:

• estimating characteristic properties of the formation ;
• estimating in-situ stresses in the formation;
• estimating or determining characteristic properties of said fluids;
• estimating the rock strength of said formation;
• conducting at least one pore pressure versus time laboratory test based on said estimations of fluid properties, formation properties, and rock strength;
• employing results of said test, said estimations of formation Properties, in-situ stresses, rock strength and said fluid properties in a wellbore stability model;
• using results from said model to adjust estimates of said formation properties, in-situ stresses in the formation;
• and rock strength to update said wellbore stability model or using results horn said model to adjust the properties of said fluids to maintain or enhance said rock strength;
• continuing during said operations to estimate or measure characteristic properties of the formation and of said fluids during said well operations and continuing to repeat or update on a real-time basis the estimates of in-situ stresses and rock strength based on said properties, wherein said characteristic properties of the formation which are measured during said wellbore operations comprise acoustic, sonic, electrical, thermal, and transient pressure responses of the formation;
• and
• continuing to update the wellbore stability model and continuing to adjust on a real-time basis the properties of said fluids as needed to maintain or enhance said rock strength during said operation.

A method for real-time monitoring the interaction of a subterranean formation with fluids injected into or circulating in a wellbore penetrating said formation for real-time monitoring of the stability of said formation while recovering hydrocarbons from said formation, said method comprising:

• constructing an earth-model of the formation adjacent or near the wellbore;
• predicting suitable fluids for use in said wellbore;
• conducting laboratory experiments to ascertain time-dependent formation behavior in the presence of said predicted suitable fluids;
• measuring rock properties in said experiments;
• calibrating a wellbore stability model based on said measured rock properties;
• injecting or circulating said fluids in said wellbore;
• measuring real-time static and dynamic rock properties while said fluids are in said wellbore;
• updating said wellbore stability model with said real-time measurements;
• adjusting the properties of said fluids as needed to maintain wellbore stability according to said model;
• repeating said real-time measuring of rock properties and said updating of the wellbore stability model during said injection or circulating of said fluids in said wellbore enough times that the interaction of said subterranean formation with said fluids may be monitored on a real-time basis such that the formation stability may be monitored on a real-time basis.