Abstract: Systems and methods include a computer-implemented method for predicting hydraulic fracture initiation. A fracking operations dataset is prepared using historical field information for fracking wells. A set of hyper-parameters is tuned for use in a machine learning algorithm configured to predict fracture initiation for new fracturing wells. The dataset is divided into training and test datasets. A regression algorithm is applied to train the training dataset and to validate with the test dataset. A target variable of a breakdown pressure for a new hydraulic fracturing treatment is determined. A prediction dataset is updated using at least the target variable. The training dataset is trained using a classifier of the machine learning algorithm. A prediction is made using the prediction dataset whether the new hydraulic fracturing treatment can be initiated or not. The breakdown pressure is incrementally adjusted, and the method is repeated until successful hydraulic fracture initiation is predicted.

Abstract: Techniques for fracturing a formation include receiving a data representing depth-dependent horizontal in-situ stress and a fracture toughness for one or more layers of the formation, predicting a hydraulic fracture profile within the formation, and pumping a fluid into a wellbore to fracture the formation at a perforation location based on the predicted hydraulic fracture profile. Predicting the hydraulic fracture profile can include determining a location of an upper portion of the fracture profile when an upper fracture tip stress intensity factor satisfies an upper fracture tip propagation condition, and determining a location of a lower portion of the fracture profile when a lower fracture tip stress intensity factor satisfies a lower fracture tip propagation condition. Predicting the hydraulic fracture profile can include determining a depth-dependent width profile of the hydraulic fracture based on the determined locations of the upper and lower portions.

Abstract: Techniques for stimulating a formation surrounding a wellbore include determining a rock type of the formation along the well trajectory in landing zone in terms of measured depth. A depth-specific acid fracture conductivity parameter of the formation and a depth-specific fracture conductivity declining parameter of the formation are determined. One or more depth intervals requiring fracturing are determined based on the rock type of the formation, the acid fracture conductivity parameter of the formation, and the fracture conductivity declining parameter of the formation. A fracturing method is determined for each depth interval of the one or more depth intervals based on the acid fracture conductivity parameter of the formation and the fracture conductivity declining parameter of the formation. A corresponding pump schedule of the fracturing method is determined, and a fluid of the pump schedule is pumped into the wellbore to fracture or stimulate the formation.

Abstract: A system for determining a direction for drilling a well is disclosed. The system has a device in a portion of a conveyance mechanism comprising a cylindrical housing with at least one sensor that tracks a position of the portion during a drilling operation, the device being configured to obtain a plurality of drilling parameters, and a control system coupled to the device and configured to perform at least one reservoir simulation, and prepare a plurality of required parameters while drilling. The device uses an optimization box to simulate increasing an angle between a drilling direction and a maximum horizontal stress by calculating a minimum mud pressure required to prevent borehole collapse. The control system generates an engineering curve representative of each angle simulated and a corresponding mud weight or pressure, and the device and the control system identify an optimal direction corresponding to a minimum drilling mud pressure parameter.

Abstract: A bottom hole assembly (BHA) includes components to perform a fracturing process for small hole wells created by underbalanced coiled tubing drilling. The BHA can be used to drill a wellbore and to stimulate an underbalanced coiled tubing drilled well. The BHA, coupled to a coiled tubing, can include a drilling bit, a hydrajetting tool up-string from the drilling bit, and a diverter between the drilling bit and the hydrajetting tool. After the BHA drills a wellbore, the BHA can be moved so that the hydrajetting tool is positioned to perform perforation without removing the BHA from the wellbore. The hydrajetting tool can perforate the formation using a regular perforation fluid first, then using a cooling agent to cool the wellbore area covering the coplanar perforation cluster, and last propagate hydraulic fracture by injecting the main pump schedule through the tubing and the annulus at the same time.

Abstract: Systems and methods for determining optimal perforation orientations for hydraulic fracturing of wells in a subterranean formation are presented. The method comprises identifying in-situ stresses for a portion of a well bore formed and transforming the in-situ stresses between coordinate systems. Pressure coefficients and a breakdown pressure for each trial perforation phase angle at a perforation cluster determined, and a perforation point in the well bore coordinate system is calculated for each trial perforation phase angle of the perforation cluster. The perforation point in the well bore coordinate system is transformed to the translated global coordinate system for each trial perforation phase angle. A target perforation phase angle is selected at a minimum breakdown pressure for the perforation cluster, and a perforation azimuth and perforation dip is calculated for the perforation cluster at the minimum breakdown pressure for the target perforation phase angles.

Abstract: A bottom hole assembly (BHA) includes components to perform a fracturing process for small hole wells created by underbalanced coiled tubing drilling. The BHA can be used to drill a wellbore and to stimulate an underbalanced coiled tubing drilled well. The BHA, coupled to a coiled tubing, can include a drilling bit, a hydrajetting tool up-string from the drilling bit, and a diverter between the drilling bit and the hydrajetting tool. After the BHA drills a wellbore, the BHA can be moved so that the hydrajetting tool is positioned to perform perforation without removing the BHA from the wellbore. The hydrajetting tool can perforate the formation using a regular perforation fluid first, then using a cooling agent to cool the wellbore area covering the coplanar perforation cluster, and last propagate hydraulic fracture by injecting the main pump schedule through the tubing and the annulus at the same time.

Abstract: A method includes gathering data about the well and the deep and tight sandstone reservoir, evaluating a diagenetic rock typing and a flow index of the reservoir using the data, and determining a first set of perforation locations based on the diagenetic rock typing and the flow index. The method also includes calibrating in-situ stresses based on the data and determining a breakdown pressure envelope and optimal perforation directions using the in-situ stresses, maximum horizontal stress direction, formation mechanical properties, and well trajectory.

Abstract: A method includes gathering data about the well and the deep and tight sandstone reservoir, evaluating a diagenetic rock typing and a flow index of the reservoir using the data, and determining a first set of perforation locations based on the diagenetic rock typing and the flow index. The method also includes calibrating in-situ stresses based on the data and determining a breakdown pressure envelope and optimal perforation directions using the in-situ stresses, maximum horizontal stress direction, formation mechanical properties, and well trajectory.

Abstract: Techniques for hydraulic fracturing a subsurface formation can include using a deterministic model to simulate a deviated well comprising a casing and at least one perforation tunnel. The techniques can include determining a different statistical distribution for each of one or more parameters to the deterministic model. The statistical distributions can be determined from the log data along the measured depth within the wellbore. The techniques can include probabilistically solving the deterministic model to determine a mean and a standard deviation of breakdown pressures along the measured depth within the wellbore. The techniques can include processing the mean and the standard deviation of breakdown pressures to determine an upper bound breakdown pressure based on a level of confidence. The techniques can include drilling and completing a deviated well based on the determined upper bound breakdown pressure and injecting hydraulic fluid to cause hydraulic fracturing of the subsurface formation.

Abstract: Systems and methods include a technique for drilling and fracturing wells. Geomechanical properties and in-situ stresses for the field are estimated using collected data and results from mini-fracking tests. A 3D geomechanics model for the field is generated based on 3D property model and natural fracture network. First 3D hydraulic fracturing modeling for a single well is conducted to obtain an optimum pump schedule for a target fracture length and well spacing for placing numerous horizontal wells in the field. Then 3D hydraulic fracturing modeling for the multiple wells is conducted based on a drilling-fracturing sequence configured to generate symmetric fractures and to determine an optimum pump schedule for middle wells, considering tensile stress superposition. The drilling-fracturing sequence includes initially skipping fracturing of a drilled well adjacent to a fractured well. The group of wells are drilled and fractured using the sequence.

Abstract: Systems and methods include techniques for determining whether to use underbalanced coiled tubing drilling (UBCTD) or conventional drilling with hydraulic fracturing to drill a new well in deep and tight reservoirs with slow rate of penetration issues. Estimates of geomechanical properties and image log processing for past-drilled wells are completed first, then three-dimensional (3D) property modeling and natural fracture prediction (NFP) for the domain are conducted. Then a 3D geomechanics model is generated. After this the rock properties and NFP along the planned well trajectory are extracted. The diagenetic rock typing is evaluated. Required breakdown pressure for hydraulic fracturing is calculated. A determination based on the diagenetic rock typing and required breakdown pressure is made whether UBCTD or conventional drilling with hydraulic fracturing should be used for a new well.

Abstract: A perforation cluster of a longitudinal section of a wellbore is provided. The wellbore is for hydraulic fracturing in a preferred direction of a subsurface surrounding the longitudinal section. The longitudinal section has a longitudinal axis in a longitudinal direction and defining a radial direction about the longitudinal axis. The perforation cluster includes all of the perforations of the wellbore within the longitudinal section. The perforations are separated in the longitudinal and radial directions. Two perforations are adjacent in the longitudinal direction and have a first diameter. They also have respective centers that are aligned in the preferred direction with respect to the longitudinal axis and 180° apart in the radial direction, for initiating fractures through hydraulic fracturing in the subsurface. The remaining perforations have a second diameter smaller than the first diameter.

Abstract: A system for determining a direction for drilling a well is disclosed. The system has a device in a portion of a conveyance mechanism comprising a cylindrical housing with at least one sensor that tracks a position of the portion during a drilling operation, the device being configured to obtain a plurality of drilling parameters, and a control system coupled to the device and configured to perform at least one reservoir simulation, and prepare a plurality of required parameters while drilling. The device uses an optimization box to simulate increasing an angle between a drilling direction and a maximum horizontal stress by calculating a minimum mud pressure required to prevent borehole collapse. The control system generates an engineering curve representative of each angle simulated and a corresponding mud weight or pressure, and the device and the control system identify an optimal direction corresponding to a minimum drilling mud pressure parameter.

Abstract: A perforation cluster of a longitudinal section of a wellbore is provided. The wellbore is for hydraulic fracturing in a preferred direction of a subsurface surrounding the longitudinal section. The longitudinal section has a longitudinal axis in a longitudinal direction and defining a radial direction about the longitudinal axis. The perforation cluster includes all of the perforations of the wellbore within the longitudinal section. The perforations are separated in the longitudinal and radial directions. Two perforations are adjacent in the longitudinal direction and have a first diameter. They also have respective centers that are aligned in the preferred direction with respect to the longitudinal axis and 180° apart in the radial direction, for initiating fractures through hydraulic fracturing in the subsurface. The remaining perforations have a second diameter smaller than the first diameter.

Abstract: Systems and methods for determining perforation orientations of a subterranean formation for a hydraulic fracturing treatment are presented. The method comprises identifying in-situ stresses for a portion of a wellbore formed from a terranean surface into a subterranean formation. The method also includes transforming the in-situ stresses from a global coordinate system to a wellbore coordinate system at a perforation cluster of the wellbore that comprises at least one perforation tunnel for a hydraulic fracturing treatment. The in-situ stresses are transformed from the wellbore coordinate system to a perforation coordinate system through at least one rotation matrix. Pressure coefficients and a breakdown pressure for each trial perforation phase angle at a perforation cluster determined, and a perforation point in the wellbore coordinate system is calculated for each trial perforation phase angle of the perforation cluster.

Abstract: Systems and methods include a computer-implemented method for predicting hydraulic fracture initiation. A fracking operations dataset is prepared using historical field information for fracking wells. A set of hyper-parameters is tuned for use in a machine learning algorithm configured to predict fracture initiation for new fracturing wells. The dataset is divided into training and test datasets. A regression algorithm is applied to train the training dataset and to validate with the test dataset. A target variable of a breakdown pressure for a new hydraulic fracturing treatment is determined. A prediction dataset is updated using at least the target variable. The training dataset is trained using a classifier of the machine learning algorithm. A prediction is made using the prediction dataset whether the new hydraulic fracturing treatment can be initiated or not. The breakdown pressure is incrementally adjusted, and the method is repeated until successful hydraulic fracture initiation is predicted.

Abstract: Techniques for hydraulic fracturing a subsurface formation can include using a deterministic model to simulate a deviated well comprising a casing and at least one perforation tunnel. The techniques can include determining a different statistical distribution for each of one or more parameters to the deterministic model. The statistical distributions can be determined from the log data along the measured depth within the wellbore. The techniques can include probabilistically solving the deterministic model to determine a mean and a standard deviation of breakdown pressures along the measured depth within the wellbore. The techniques can include processing the mean and the standard deviation of breakdown pressures to determine an upper bound breakdown pressure based on a level of confidence. The techniques can include drilling and completing a deviated well based on the determined upper bound breakdown pressure and injecting hydraulic fluid to cause hydraulic fracturing of the subsurface formation.

Abstract: Some methods of hydraulic fracturing of a subsurface formation include using a three-dimensional finite element model to simulate a deviated well with a wellbore casing, a cement adjacent to the wellbore casing, and a perforation cluster with at least two perforations. The FEM is applied (or solved) to determine a breakdown pressure of the deviated well based on an amount of tensile damage of the perforation cluster induced by an applied pressure representing injected hydraulic fluid. The FEM accounts for the 3D complex configuration of wellbore and perforation cluster. A deviated well is drilled and completed with a wellbore casing size, tubing size, wellhead, and hydraulic fracturing pump schedule selected at least in part based on the determined breakdown pressure before hydraulic fluid is injected into the deviated well at an injection pressure, which represents the required breakdown pressure to cause hydraulic fracturing of the rock of the subsurface formation.

Abstract: Some methods of hydraulic fracturing of a subsurface formation include using a three-dimensional finite element model to simulate a deviated well with a wellbore casing, a cement adjacent to the wellbore casing, and a perforation cluster with at least two perforations. The FEM is applied (or solved) to determine a breakdown pressure of the deviated well based on an amount of tensile damage of the perforation cluster induced by an applied pressure representing injected hydraulic fluid. The FEM accounts for the 3D complex configuration of wellbore and perforation cluster. A deviated well is drilled and completed with a wellbore casing size, tubing size, wellhead, and hydraulic fracturing pump schedule selected at least in part based on the determined breakdown pressure before hydraulic fluid is injected into the deviated well at an injection pressure, which represents the required breakdown pressure to cause hydraulic fracturing of the rock of the subsurface formation.