Abstract: Systems and methods for quantifying drilling fluid influence on formation mechanical properties are disclosed. The methods include obtaining drilling mud formulations and properties; determining a subset of the drilling mud formulations; obtaining core plugs from a subsurface; measuring first rock mechanical properties from the core plugs for each of the subset of the drilling mud formulations; performing a fluid invasion of the core plugs with drilling muds; measuring second rock mechanical properties of the core plugs after the fluid invasion; modeling an effect of the drilling muds on a formation breakdown; determining a mud weight range for each of the subset of the drilling mud formulations; and selecting a preferred drilling mud formulation for a drilling operation based on the mud weight range for the subset of the drilling mud formulations.

Abstract: In some examples, a system includes a stress field assessment engine, implemented by at least one processor, to determine stress distribution and yield state data based on a geomechanical model, and a natural fracture determination engine, implemented by the at least one processor, to generate a natural fracture network model based on the stress distribution and yield state data. The system may implement a method that includes generating a geomechanical model of a subsurface formation, where the geomechanical model includes a formation model and a wellbore model, simulating the geomechanical model to determine stress distributions and yield states in the subsurface formation, and generating a natural fracture network model using a machine learning technique on the stress distributions and yield states.

Abstract: A method for obtaining mechanical earth model (MEM) parameters, the method involving obtaining an ultrasonic image log for a borehole, based on the ultrasonic image log, obtaining an estimate of a borehole geometry for an entire circumference of the borehole in an interval of the ultrasonic image log, and estimating the MEM parameters using the estimate of the borehole geometry.

Abstract: Systems and methods for constraining rate of penetration through a loading rate and drillstring vibrations analysis are disclosed. The methods include obtaining a rock type of a formation to be drilled, determining a rock-type specific loading rate model for the rock type, obtaining surface drilling parameters for each of a plurality of rate of penetration (ROP) values; and obtaining a plurality of bottom hole assembly (BHA) designs. The methods further include determining impact forces for each of the plurality of BHA designs using a drill string vibrational model and the surface drilling parameters, predicting rock failure using the impact forces, rock type specific loading rate model, and a finite element model (FEM), and selecting particular surface drilling parameters based on the predicted rock failure.

Abstract: In some examples, an initial wellbore model that includes a formation model and main wellbore model can be generated. The initial wellbore model can be simulated to compute stress distributions in the formation model caused during main wellbore model formation. The initial wellbore model can be updated to include a lateral wellbore model to provide an updated wellbore model in response to the simulation of the initial wellbore model. The updated wellbore model can be simulated to compute updated stress distributions in the formation model caused during lateral wellbore model formation using the determined stress distributions.

Abstract: A computer-implemented method, medium, and system for converting borehole images into three dimensional structures for numerical modeling and simulation applications are disclosed. In one computer-implemented method, multiple CT-scan images of a core sample of a rock are received, where the core sample includes a borehole, and the multiple CT-scan images are cross-section images of the core sample at multiple depths of the borehole. A triangulation process is performed on pixels of each CT-scan image and with respect to each of multiple circumferential position angles. Multiple radii of the borehole corresponding to the multiple circumferential position angles are determined for each CT-scan image. Multiple nodal coordinates of 3D numerical model mesh of the borehole are generated based on the multiple radii of the borehole. An advisory on drilling window limits of mud weight is provided based on the multiple nodal coordinates of the 3D numerical model mesh of the borehole.

Abstract: Systems and methods for determining a failure criterion for a rock and using the failure criterion to determine a structural integrity of a wellbore include one or more of the following features. Some systems extract a core sample of the rock from the wellbore and acquiring images of the core sample. Some systems generate a finite element model of the core sample that includes a failure criterion, solve the model to generate nodal data, and use the nodal data to determine failure regions of the core sample. Some systems compare the images of the core sample to the failure regions of the core sample to determine confusion matrix parameters associated with nodes of the model. Some systems select the failure criterion based on an overall score of the confusion matrix parameters, and use the selected failure criterion to predict a structural integrity of the wellbore.

Abstract: The systems and methods described in this specification relate to installing a wellbore completion setup of a wellbore based on a probability within a reservoir. The systems and methods measure one or more properties of the formation and receive data representing the one or more measured properties. The systems and methods use the one or more properties as input conditions to a finite element model of the wellbore. The systems and methods solve the finite element model to determine stresses of the formation surrounding the wellbore. The systems and methods determine a size of one or more rock fragments based on whether the determined stresses from the finite element model are greater than a threshold stress of a failure criterion. The systems and methods determine the probability, select the wellbore completion setup of the wellbore based on the bridging probability, and install the selected wellbore completion setup in the wellbore.

Abstract: The present disclosure describes methods and systems for downhole well integrity reconstruction in a hydrocarbon reservoir. One method for downhole well integrity reconstruction in a hydrocarbon reservoir includes: positioning, a laser head at a first subterranean location, wherein the laser head is attached to a tubular inside of a wellbore; directing, by the laser head, a laser beam towards a leak on the wellbore; and sealing the leak using the laser beam.

Abstract: A computer-implemented method, medium, and system for converting borehole images into three dimensional structures for numerical modeling and simulation applications are disclosed. In one computer-implemented method, multiple CT-scan images of a core sample of a rock are received, where the core sample includes a borehole, and the multiple CT-scan images are cross-section images of the core sample at multiple depths of the borehole. A triangulation process is performed on pixels of each CT-scan image and with respect to each of multiple circumferential position angles. Multiple radii of the borehole corresponding to the multiple circumferential position angles are determined for each CT-scan image. Multiple nodal coordinates of 3D numerical model mesh of the borehole are generated based on the multiple radii of the borehole. An advisory on drilling window limits of mud weight is provided based on the multiple nodal coordinates of the 3D numerical model mesh of the borehole.

Abstract: A method includes taking at least one image of a plurality of returned rock fragments from a wellbore using a camera, analyzing the at least one image with an image analysis program to detect a caving in the plurality of returned rock fragments, constructing a model of the caving, and incorporating the model of the caving into a finite element geomechanics model of the wellbore using a meshing program to create an adjusted model of the wellbore.

Abstract: The present disclosure describes methods and systems for downhole well integrity reconstruction in a hydrocarbon reservoir. One method for downhole well integrity reconstruction in a hydrocarbon reservoir includes: positioning, a laser head at a first subterranean location, wherein the laser head is attached to a tubular inside of a wellbore; directing, by the laser head, a laser beam towards a leak on the wellbore; and sealing the leak using the laser beam.

Abstract: Disclosed are methods of preparing drilling fluid compositions containing treated calcium bentonite. One such method includes mixing calcium bentonite with an aqueous mixture containing soda ash, followed by adding starch to form the treated bentonite mixture that is used to prepare a drilling fluid composition. Another method includes mixing the calcium bentonite with an aqueous mixture containing soda ash and magnesium oxide, followed by adding starch to form the treated bentonite mixture that is used to prepare a drilling fluid composition.

Abstract: Embodiments provided herein include systems and methods for monitoring wellbore integrity throughout a wellbore lifecycle. These embodiments include creating an initial wellbore integrity model that determines a geomechanical stability of a wellbore for drilling, the wellbore for harvesting fluid hydrocarbons, where creating the initial wellbore integrity model includes determining the wellbore and determining first input data of a subsurface into which the wellbore is planned. Some embodiments include drilling the wellbore as s part of a drilling phase of a life cycle of the wellbore and performing drilling phase analysis. Some embodiments include determining drilling in-situ stresses of the wellbore during the drilling phase, determining a drilling phase mud window, creating an updated wellbore integrity model, and predicting from the updated wellbore integrity model whether there is a first issue with the wellbore.

Abstract: A sealing composition for sealing an annulus of a wellbore includes from 20 weight percent to 97 weight percent epoxy resin based on the total weight of the composition. The epoxy resin comprising at least one of 2,3-epoxypropyl o-tolyl ether, alkyl glycidyl ethers having from 12 to 14 carbon atoms, or a compound having formula (OC2H3)—CH2—O—R1—O—CH2—(C2H3O), where R1 is a linear or branched hydrocarbyl having from 4 to 24 carbon atoms. The sealing composition also includes from 1 weight percent to 20 weight percent curing agent based on the total weight of the composition. Methods for sealing a wellbore annulus or casing-casing annulus includes introducing a spacer fluid to the wellbore, introducing the sealing composition to the wellbore, displacing the sealing composition into the annulus, and curing the sealing composition.

Abstract: A sealing composition for sealing an annulus of a wellbore includes from 20 weight percent to 97 weight percent epoxy resin based on the total weight of the composition. The epoxy resin comprising at least one of 2,3-epoxypropyl o-tolyl ether, alkyl glycidyl ethers having from 12 to 14 carbon atoms, or a compound having formula (OC2H3)—CH2—O—R1—O—CH2—(C2H3O), where R1 is a linear or branched hydrocarbyl having from 4 to 24 carbon atoms. The sealing composition also includes from 1 weight percent to 20 weight percent curing agent based on the total weight of the composition.

Abstract: A well bore cementing system may comprise a spacer fluid and a cement slurry. The spacer fluid may be positioned within a well bore, and the spacer fluid may comprise a first surfactant package comprising one or more surfactants. The cement slurry may be positioned within the well bore, and the cement slurry may comprise a second surfactant package comprising one or more surfactants.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for improving wellbore stability and minimizing wellbore failure issues. In one aspect, a method includes receiving, for a well site, post-drilling parameters; clustering the received post-drilling parameters into groups based on an information type of each post-drilling parameter; generating a correlation model by applying a numerical analysis or a statistical analysis to the post-drilling parameters included in each of the groups; determining a resolution to avoid wellbore failure at a new well site by processing information regarding the new well site through the correlation model; and transmitting the resolution for implementation at the well site.

Abstract: In one embodiment, a spacer fluid may comprise a base fluid and a surfactant package. The surfactant package may comprise one or more surfactants, where the surfactant package comprises a first surfactant having the chemical structure R—(OC2H4)x—OH. R may be a hydrocarbyl group having from 9 to 20 carbon atoms, and x may be an integer from 5 and 15. The first surfactant may have a hydrophilic-lipophilic balance (HLB) of from 12 to 13.5.

Abstract: Embodiments are directed to a lubricant package for water based drilling fluids. The lubricant package includes water, a polyethylene glycol, and a lubricating agent. The lubricating agent includes triethanolamine, or a C12-C14 alcohol ethoxylate, or a combination of triethanolamine and C12-C14 alcohol ethoxylate. The weight ratio of the polyethylene glycol to the lubricating agent in the lubricant package is from 1:2 to 2:1. Embodiments are also directed to a water-based drilling fluid composition including an aqueous base fluid, one or more additives, and the lubricant package for water based drilling fluids.