Saudi Arabian Oil Company

Tariq Mahmood

Otto E Meza Camargo

Kaiming Xia

Antonio A Santagati

Khalid Hawas

Otto Meza Camargo

Khaqan Khan

Edwin Caliboso

Qiuguo Li

Augustine Ikenna Monyei

Saidi Ali Hassani

Todd Allen Green

Methods and systems for determining pore-volume of a fracture in a core plug. The method includes developing a grid block model constrained by fracture porosity estimated from a mechanical laboratory test, aperture calculation, and discrete fracture model validation. The method further includes determining the natural fracture porosity and pore volume from the equivalent medium for natural fractures, determining oil or gas reserves by calculating the fracture pore volume, and determining fracture porosity measurement from a test to calibrate 3D fracture models. The method also includes determining fracture porosity from a mechanical test, analyzing borehole image logs, developing a geomechanical model and fracture drivers, performing fracture model predictions, validating and calibrating the model, and determining fracture pore-volume of the core plug.

Methods and systems for determining reservoir and fracture properties

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.

Stimulating wells created by underbalanced coiled tubing drilling

Systems and methods for predicting drill bit wearing state using drilling parameters and formation properties are disclosed. The methods include, for each of a plurality of past bit runs, obtaining a measured rock property value and a measured drilling variable value for the past bit run, and obtaining a measured dull grade for a drill bit used for the past bit run. The methods also include determining parameters of a functional relationship between the measured dull grade, the bit run time, the measured rock property value, and the measured drilling variable value, and predicting a predicted dull grade for a future bit run using a new drill bit. The methods further include replacing the new drill bit with a replacement drill bit at a time based, at least in part, on the predicted dull grade.

Method for predicting rock formation abrasiveness and bit wear

Images of subsurface formation walls adjacent well bores are obtained by the borehole imaging systems. The borehole images are processed to characterize the nature of fractures in the formation walls. The fractures are characterized as natural fractures or stress-induced tensile fractures based on the borehole image processing for geomechanical modeling in connection with reservoir characterization, fracture modeling, and stress analysis. A capability is provided to discriminate between the natural fractures and the stress induced tensile fractures and for performance of well activities.

Discrimination between subsurface formation natural fractures and stress induced tensile fractures based on borehole images

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.

Fracturing a subsurface formation based on the required breakdown pressure

Fracture porosity and permeability variations with increasing effective stress, are measured and determined by laboratory testing of rock cylindrical core plugs of various types (carbonate, silico-clastic, shale, e.g.) and dimensions. The testing can be implemented for both natural and induced fractures propagating axially in the rock core plug. The testing begins with initial testing, sample preparation and obtaining measurements on an intact plug to define matrix properties in the rock core plug. A rock core plug with defined matrix properties is then after further preparation, subjected to an axial shear fracture (natural or induced) propagating through its body. Measurements are then obtained from the plug with an axial shear fracture (natural or induced) propagating through its body to determine fracture properties.

Laboratory measurement of dynamic fracture porosity and permeability variations in rock core plug samples

Earth models of stress conditions in subsurface reservoirs are formed reflecting rock mechanical properties, stress regime and also wellbore stability. A number of variables related to the rock mechanical properties and stress conditions are parameterized. The variability of minimum horizontal stress magnitudes as a product of the relative contributions of the various rock properties and input parameters or variables used to form the model is analyzed. Differences between predicted minimum horizontal stress magnitudes in the formation and an actual measurement obtained from the formation (for example, fracture closure pressure) are determined. The determined differences are the minimized through an optimization methodology to find a best set of parameters suitable to match the minimum horizontal stress to actual formation measurement.

Determination of calibrated minimum horizontal stress magnitude using fracture closure pressure and multiple mechanical earth model realizations

In reservoir hydrocarbon exploration, fracture characteristics of subsurface reservoir formations are analyzed based on measures obtained about the subsurface formations and rock. Models of subsurface reservoirs are developed with predictions of natural fracture networks within the subject subsurface reservoirs. The mechanical properties of the formation rock in the reservoirs serve as a main controller to model the natural fractures distribution and their properties. The models so formed are important in the location and completion of wells for hydrocarbon exploration and production.

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Dhahran, Saudi Arabia

Tariq Mahmood