The invention discloses a method for determining vertical well stratified fracturing crack length based on interlayer equilibrium development. According to the method, interlayer equilibrium development can be achieved by determining the crack length of fracturing of each layer in the condition that an oil well meets the productivity requirements. The method comprises the following steps: 1) a threshold pressure gradient of each layer is determined; 2) a relationship chart of the crack half-length x.sub.f and the equivalent well diameter r.sub.we is established; 3) daily oil production rate per unit thickness Q.sub.c meeting the production requirements is calculated; 4) the equivalent well diameter r.sub.we of each layer is calculated according to the daily oil production rate Q.sub.c; and 5) the crack half-length x.sub.f of fracturing of each layer is calculated according to the equivalent well diameter r.sub.we of each layer.

The invention discloses a method for determining vertical well stratified fracturing crack length based on interlayer equilibrium development. According to the method, interlayer equilibrium development can be achieved by determining the crack length of fracturing of each layer in the condition that an oil well meets the productivity requirements. The method comprises the following steps: 1) a threshold pressure gradient of each layer is determined; 2) a relationship chart of the crack half-length x.sub.f and the equivalent well diameter r.sub.we is established; 3) daily oil production rate per unit thickness Q.sub.c meeting the production requirements is calculated; 4) the equivalent well diameter r.sub.we of each layer is calculated according to the daily oil production rate Q.sub.c; and 5) the crack half-length x.sub.f of fracturing of each layer is calculated according to the equivalent well diameter r.sub.we of each layer.

The present disclosure introduces an apparatus including a toolstring for use in a tubular extending into a subterranean formation. The toolstring includes modular components that include one or more caliper modules and a power and control (P/C) module. The one or more caliper modules each include radially rotatable fingers for sensing an internal diameter of the tubular. The P/C module is operable for distributing power and control signals to the one or more caliper modules. The caliper and P/C modules are mechanically and electrically interconnected by common lower interfaces of the caliper and P/C modules.

The present disclosure introduces an apparatus including a toolstring for use in a tubular extending into a subterranean formation. The toolstring includes modular components that include one or more caliper modules and a power and control (P/C) module. The one or more caliper modules each include radially rotatable fingers for sensing an internal diameter of the tubular. The P/C module is operable for distributing power and control signals to the one or more caliper modules. The caliper and P/C modules are mechanically and electrically interconnected by common lower interfaces of the caliper and P/C modules.

The present disclosure introduces an apparatus including a toolstring for use in a tubular extending into a subterranean formation. The toolstring includes modular components that include one or more caliper modules and a power and control (P/C) module. The one or more caliper modules each include radially rotatable fingers for sensing an internal diameter of the tubular. The P/C module is operable for distributing power and control signals to the one or more caliper modules. The caliper and P/C modules are mechanically and electrically interconnected by common lower interfaces of the caliper and P/C modules.

The present disclosure introduces an apparatus including a toolstring for use in a tubular extending into a subterranean formation. The toolstring includes modular components that include one or more caliper modules and a power and control (P/C) module. The one or more caliper modules each include radially rotatable fingers for sensing an internal diameter of the tubular. The P/C module is operable for distributing power and control signals to the one or more caliper modules. The caliper and P/C modules are mechanically and electrically interconnected by common lower interfaces of the caliper and P/C modules.

Apparatus for measuring the profile of a wellbore includes a cylindrical body having first and second ends threaded for connection in line with a drill string. A passage extends through the body between the first and second ends. A plurality of arms are pivotally coupled on an outer surface of the cylindrical body. Each of the arms is biased to pivot so as to move a free end of the arm to move radially away from the outer surface of the body. The plurality of arms are angularly spaced apart around the cylindrical body and arranged in a plurality of tiers. Each of the tiers comprises three or more of the arms. The tiers are spaced apart axially from one another along the cylindrical body. Sensors are operable to directly or indirectly measure radial extension of each of the arms from the cylindrical body. A holding mechanism is operable to hold the arms in a retracted configuration and to selectively release the arms to pivot away from the cylindrical body. The arms may be extended while withdrawing a drillstring containing the apparatus from a wellbore to monitor a profile of a wall of the wellbore.

Apparatus for measuring the profile of a wellbore includes a cylindrical body having first and second ends threaded for connection in line with a drill string. A passage extends through the body between the first and second ends. A plurality of arms are pivotally coupled on an outer surface of the cylindrical body. Each of the arms is biased to pivot so as to move a free end of the arm to move radially away from the outer surface of the body. The plurality of arms are angularly spaced apart around the cylindrical body and arranged in a plurality of tiers. Each of the tiers comprises three or more of the arms. The tiers are spaced apart axially from one another along the cylindrical body. Sensors are operable to directly or indirectly measure radial extension of each of the arms from the cylindrical body. A holding mechanism is operable to hold the arms in a retracted configuration and to selectively release the arms to pivot away from the cylindrical body. The arms may be extended while withdrawing a drillstring containing the apparatus from a wellbore to monitor a profile of a wall of the wellbore.

A method can include energizing a tube with a longitudinally extending magnetic field generated inside the tube, using a magnetic field-detecting logging tool to generate magnetic flux signals generated inside the tube externally of the material of the tube wall resulting from such energizing at circumferential locations on the inner surface of the tube and at distances along the tube, iteratively using a model of the relationship between the generated magnetic flux signals and the thickness of the tube wall to derive a thickness profile of the tube wall by using (i) the magnetic permeability of the tube material deduced from the magnetic flux signals and (ii) a defect-free flux parameter representative of any non-linearity between the magnetic field strength and flux density in the tube, the iteration including using the model to calculate an initial approximate wall thickness profile using an initial estimate of the defect-free flux parameter.

A method can include energizing a tube with a longitudinally extending magnetic field generated inside the tube, using a magnetic field-detecting logging tool to generate magnetic flux signals generated inside the tube externally of the material of the tube wall resulting from such energizing at circumferential locations on the inner surface of the tube and at distances along the tube, iteratively using a model of the relationship between the generated magnetic flux signals and the thickness of the tube wall to derive a thickness profile of the tube wall by using (i) the magnetic permeability of the tube material deduced from the magnetic flux signals and (ii) a defect-free flux parameter representative of any non-linearity between the magnetic field strength and flux density in the tube, the iteration including using the model to calculate an initial approximate wall thickness profile using an initial estimate of the defect-free flux parameter.