Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to simulating subterranean fracture propagation. A subterranean formation model representing rock blocks of a subterranean formation is received. The subterranean formation model is used to predict a response of each rock block to one or more forces acting on the rock block during an injection treatment for the subterranean formation. The predicted responses of the rock blocks may include, for example, a fracture, a rotation, a displacement, a dilation of an existing fracture, and/or another type of response. In some implementations, an injection treatment may be designed for a subterranean formation based on the predicted response of the rock blocks.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to refining information on characteristics of natural fractures of a subterranean formation. Fracture pattern models are generated based on sampling an initial distribution of values for a fracture parameter. Each fracture pattern model may include, for example, a model of natural fractures in a subterranean formation. Each fracture pattern model is compared to microseismic event data for a subterranean region. A refined distribution for the fracture parameter is generated based on the comparison. Generating the refined distribution may include, for example, selecting values of the fracture parameter from fracture pattern models that correlate with the microseismic event data. In some implementations, an injection treatment may be simulated and/or designed based on the refined distribution.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to simulating subterranean fracture propagation. A subterranean formation model representing rock blocks of a subterranean formation is received. The subterranean formation model is used to predict a response of each rock block to one or more forces acting on the rock block during an injection treatment for the subterranean formation. The predicted responses of the rock blocks may include, for example, a fracture, a rotation, a displacement, a dilation of an existing fracture, and/or another type of response. In some implementations, an injection treatment may be designed for a subterranean formation based on the predicted response of the rock blocks.

Abstract: Quantitative refracture diagnostic and fracture-injection/falloff models may be used in methods for oil and gas subsurface formation evaluation techniques. More particularly, such methods may be used to select candidate wells and well candidate layers for stimulation treatments in a subterranean formation. An example of a method for selecting well candidate layers for stimulation treatments in a subterranean formation may comprise the steps of: selecting a candidate well; selecting a reservoir layer to be tested; performing a quantitative refracture-candidate diagnostic test on the reservoir layer; determining at least one reservoir property of the reservoir layer using the quantitative refracture-candidate diagnostic test; and modeling a proposed stimulation treatment using the at least one reservoir property in a reservoir simulation model so as to predict the efficacy of the proposed stimulation treatment.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to generating probabilistic information on characteristics of natural fractures of a subterranean formation. Fitted fracture models are generated based on microseismic event data for a subterranean region. The fitted fracture models represent estimated locations of fractures in the subterranean region. A distribution of fracture parameter values is generated based on the fitted fracture models. The distribution includes fracture parameter values and a probability associated with each fracture parameter value. Generating the fitted fracture models may include, for example, fitting a plane, a line or another type of equation to the measured locations of microseismic events. In some implementations, an injection treatment may be simulated and/or designed based on the probability distribution.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to generating a model of a subterranean formation based on a probabilistic earth model. An earth model including a probability distribution for a property of a subterranean region is received. A subterranean formation model is generated based on sampling the probability distribution for the property. The subterranean formation model includes information on boundaries of rock blocks of a formation in the subterranean region. The subterranean formation model may be used for simulating an injection treatment applied to the formation, for example, to predict fracture propagation in the formation. In some implementations, the subterranean formation model may be used for designing an injection treatment for the formation.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to stochastic simulation of subterranean fracture propagation. A plurality of subterranean formation models, each representing a subterranean formation, are analyzed to obtain information on predicted results of applying an injection treatment to the subterranean formation. Each of the analyzed subterranean formation models is generated by simulating forces acting on rock blocks of the subterranean formation during the injection treatment. Each simulation has an input parameter value determined for that simulation based on sampling a distribution of values for a characteristic of the subterranean formation. The characteristic may include, for example, a natural fracture parameter. The information on the predicted results of applying the injection treatment may include, for example, an output probability distribution.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to simulating subterranean fracture propagation. A subterranean formation model representing rock blocks of a subterranean formation is received. The subterranean formation model is used to predict a response of each rock block to one or more forces acting on the rock block during an injection treatment for the subterranean formation. The predicted responses of the rock blocks may include, for example, a fracture, a rotation, a displacement, a dilation of an existing fracture, and/or another type of response. In some implementations, an injection treatment may be designed for a subterranean formation based on the predicted response of the rock blocks.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to simulating subterranean fracture propagation. A subterranean formation model representing rock blocks of a subterranean formation is received. The subterranean formation model is used to predict a response of each rock block to one or more forces acting on the rock block during an injection treatment for the subterranean formation. The predicted responses of the rock blocks may include, for example, a fracture, a rotation, a displacement, a dilation of an existing fracture, and/or another type of response. In some implementations, an injection treatment may be designed for a subterranean formation based on the predicted response of the rock blocks.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to generating a model of a subterranean formation based on a probabilistic earth model. An earth model including a probability distribution for a property of a subterranean region is received. A subterranean formation model is generated based on sampling the probability distribution for the property. The subterranean formation model includes information on boundaries of rock blocks of a formation in the subterranean region. The subterranean formation model may be used for simulating an injection treatment applied to the formation, for example, to predict fracture propagation in the formation. In some implementations, the subterranean formation model may be used for designing an injection treatment for the formation.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to stochastic simulation of subterranean fracture propagation. A plurality of subterranean formation models, each representing a subterranean formation, are analyzed to obtain information on predicted results of applying an injection treatment to the subterranean formation. Each of the analyzed subterranean formation models is generated by simulating forces acting on rock blocks of the subterranean formation during the injection treatment. Each simulation has an input parameter value determined for that simulation based on sampling a distribution of values for a characteristic of the subterranean formation. The characteristic may include, for example, a natural fracture parameter. The information on the predicted results of applying the injection treatment may include, for example, an output probability distribution.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to generating probabilistic information on characteristics of natural fractures of a subterranean formation. Fitted fracture models are generated based on microseismic event data for a subterranean region. The fitted fracture models represent estimated locations of fractures in the subterranean region. A distribution of fracture parameter values is generated based on the fitted fracture models. The distribution includes fracture parameter values and a probability associated with each fracture parameter value. Generating the fitted fracture models may include, for example, fitting a plane, a line or another type of equation to the measured locations of microseismic events. In some implementations, an injection treatment may be simulated and/or designed based on the probability distribution.

Abstract: Systems, methods, and instructions encoded in a computer-readable medium can perform operations related to refining information on characteristics of natural fractures of a subterranean formation. Fracture pattern models are generated based on sampling an initial distribution of values for a fracture parameter. Each fracture pattern model may include, for example, a model of natural fractures in a subterranean formation. Each fracture pattern model is compared to microseismic event data for a subterranean region. A refined distribution for the fracture parameter is generated based on the comparison. Generating the refined distribution may include, for example, selecting values of the fracture parameter from fracture pattern models that correlate with the microseismic event data. In some implementations, an injection treatment may be simulated and/or designed based on the refined distribution.

Abstract: A refracture-candidate diagnostic test is an injection of compressible or slightly compressible fluid at pressures in excess of minimum in-situ stress and formation fracture pressure with pressure decline following injection test recorded to detect a fracture retaining residual width from previous stimulation treatments. The diagnostic consists of small volume injections with injection time being a small fraction of time required for compressible or slightly compressible reservoir fluid to exhibit pseudoradial flow. The fracture-injection portion of a test can be considered as occurring instantaneously. Data measurements are transformed into a constant rate equivalent pressure transformation to obtain adjusted pressures or adjusted pseudovariables which are analyzed to identify dual unit-slope before and after closure periods confirming a residual retaining width.

Abstract: Methods and systems are provided for evaluating subsurface earth oil and gas formations. More particularly, methods and systems are provided for determining reservoir properties such as reservoir transmissibilities and average reservoir pressures of formation layer(s) using quantitative refracture-candidate diagnostic methods. The methods herein may use pressure falloff data from the introduction of an injection fluid at a pressure above the formation fracture pressure to analyze reservoir properties. The model recognizes that a new induced fracture creates additional storage volume in the formation and that a quantitative refracture-candidate diagnostic test in a layer may exhibit variable storage during the pressure falloff, and a change in storage may be observed at hydraulic fracture closure.

Abstract: Methods and systems are provided for evaluating subsurface earth oil and gas formations. More particularly, methods and systems are provided for determining reservoir properties such as reservoir transmissibilities and average reservoir pressures of a formation layer or multiple layers using fracture-injection/falloff test methods. The methods herein may use pressure falloff data generated by the introduction of an injection fluid at a pressure above the formation fracture pressure in conjunction with a fracture-injection/falloff test model to analyze reservoir properties. The fracture-injection/falloff test model recognizes that a new induced fracture creates additional storage volume in the formation and that a fracture-injection/falloff test in a layer may exhibit variable storage during the pressure falloff, and a change in storage may be observed at hydraulic fracture closure.

Abstract: A before-closure pressure-transient leakoff analysis for a fracture-injection/falloff test is used to mitigate the detrimental effects of pressure-dependent fluid properties on the evaluation of physical parameters of a reservoir. A fracture-injection/falloff test consists of an injection of liquid, gas, or a combination (foam, emulsion, etc.) containing desirable additives for compatibility with the formation at an injection pressure exceeding the formation fracture pressure followed by a shut-in period. The pressure falloff during the shut-in period is measured and analyzed to determine permeability and fracture-face resistance by preparing a specialized Cartesian graph from the shut-in data using adjusted pseudodata such as adjusted pseudopressure data and time as variables in a first method, and adjusted pseudopressure and adjusted pseudotime data as variables in a second method.

Abstract: The use of metal salts in vulcanizable elastomer compounds is described. In sufficient amounts, the metal salts function as both vulcanization accelerators and adhesion promoters for rubber to metal adhesion, thus eliminating the need for a separate ingredient for each purpose. Certain of the salts also promote the adhesion of the elastomer to metal adherends which have heretofore been unknown, for example, to a zinc surface. Curing characteristics of elastomer formulations using the metal salts are comparable to those using prior art accelerators.