A method for determining change in stress in a reservoir formation includes inducing a pressure pulse in a first well hydraulically connected by a fracture to the reservoir formation. A stress-related attribute of the fracture is determined from reflection events detected in pressure measurement made in the first well as a result of the inducing the pressure pulse. The inducing and determining are repeated to estimate changes in the stress-related attribute with respect to time. A method for determining and localizing type of interaction between a treated well and an observation well by monitoring pressure and fracture changes in the observation well.

Disclosed is an in-situ stress evaluation method based on a wellbore mechanical instability collapse, including: selecting a mechanical instability collapse wellbore section and classifying a data, obtaining a deep in-situ stress according to a structural strain coefficient, establishing a structural strain coefficient equation based on a wellbore stress critical equilibrium condition, obtaining the structural strain coefficient by using a least squares method and obtaining a horizontal principal stress, and estimating a reasonableness of the deep in-situ stress. The method selects data of the wellbore mechanical instability collapse and classify the data to establish a stress critical equilibrium equation based on a strain coefficient and solve an overdetermined equation based on a critical collapse formation information restriction, so as to obtain a maximum horizontal principal stress and a minimum horizontal principal stress.

This disclosure presents a method and an apparatus for improving production performance of a well using a drill stem test tool (DSTT). The method includes isolating a zone of interest in the wellbore, then reducing and recording pressure inside the drill string while recording acoustic emissions from the sensors on the DSTT, then correlating the recordings of the acoustic emissions with the pressure. The method includes using the processed acoustic emissions to determine a candidate sound of interest and a pressure at which the candidate sound of interest is recorded, then comparing the candidate sound of interest with a reference lookup table of known lithology classifications. The method includes determining a collapse pressure of the wellbore using the lithology of the wellbore and the pressure at which the candidate sound of interest is recorded.

A method of designing a cement blend for a wellbore isolation barrier based on the analysis of a stress state of the wellbore isolation barrier from the injection of CO.sub.2 into a porous formation. The analysis software may determine an optimized cement blend for a future CO.sub.2 injection schedule. The analysis software may determine a current near wellbore stress state for a current CO.sub.2 injection schedule. The analysis software may optimize a CO.sub.2 injection schedule based on the analysis of a future near wellbore stress state of the wellbore isolation barrier. The near wellbore stress state of the isolation barrier may be determined by at least one model accessed by the analysis software. The inputs into the model comprise periodic CO.sub.2 injection pressure and flowrate datasets, cement properties, and formation properties.

A tubing assembly for use in a wellbore is provided. The tubing assembly includes tubing configured to be run in a wellbore to recover downhole fluid from a formation; and at least one gauge positioned at least partially inside the tubing. The gauge is configured to detect a parameter inside the tubing.

The present invention discloses a method for predicting fracture height during fracturing stimulation in multi-layer formation, comprising specific steps of: (1) acquiring basic parameters; (2) calculating a displacement discontinuity quantity of an artificial fracture; (3) calculating induced stress generated by the fracture; (4) calculating stress intensity factors at a fracture tip without considering a fracture tip plasticity; (5) calculating sizes of a plastic zone; (6) calculating stress intensity factors at the fracture tip considering the plastic zone; and (7) judging a relationship between the stress intensity factors and a fracture toughness. The present invention is suitable for multiple stratums, and the influences of parameters of tip plasticity, induced stress, crustal stress, and rock mechanics are considered so that a calculation result is more accurate and calculation efficiency is higher.

Wireless mobile devices are injected into a wellbore with a cement slurry, during the cementing of casing, to monitor and evaluate cement sheath parameters. Passive, wireless sensors are utilized to not only measure the elastic constitutive properties of the cement sheath such as compressive strength, but also parameters of the cement sheath environment, such as temperature, pressure, humidity, pH and gases present, to identify potential issues about the structural integrity of the cement sheath, and provide timely warnings to perform remedial actions.

Distributed acoustic sensing (DAS) measurements may be acquired at an observation wellbore during a current stage of a stimulation treatment along a treatment wellbore within a reservoir formation. A cumulative strain trace for the current stage of the stimulation treatment may be determined based on the DAS measurements. Based on the cumulative strain trace, whether or not to adjust a spacing of perforation clusters and/or a stage length used at the treatment wellbore for a subsequent stage of the stimulation treatment may be determined. Responsive to determining to adjust the spacing of the perforation dusters or to adjust the stage length, at least one treatment parameter for the subsequent stage may be adjusted. The subsequent stage may be performed based on the adjusted at least one treatment parameter.

An auto-collapsible pore pressure probe device, including a support system, a penetration system and a measurement system. The support system includes a first support frame, a second support frame, a separation mechanism, a ring clamp, a fixing nut, a fixing bolt, support legs, slots, a support base, and a third support frame. The penetration system includes a rod storage wheel, a motor, a tightening mechanism, a penetration drive motor, a gear, a fixing bracket, a fixing bolt, and a friction wheel. The measurement system includes a pore pressure probe, a control cabinet, a CPTU probe, a pore pressure sensor, a probe connector, an external thread, an internal thread, a fastening strip, a connecting bolt, a connector, a data transmission and power supply cable, a displacement sensor, and a deck unit. An operating method of the pore pressure probe device is also provided.

A method includes identifying one or more stress regime types along at least a portion of a borehole, where the stress regime types are selected from a normal stress regime, a thrust stress regime and a strike-slip stress regime, and selecting reservoir access locations along the borehole based on the type of stress regime identified along the borehole.