A method for making gyroscopic azimuth measurements includes estimating a pitch angle and a roll angle of a gyroscopic surveying tool in a wellbore; determining a measurement duration for each of a plurality of gyroscope measurements from the estimated pitch and roll angles; making each of the plurality of gyroscope measurements at the determined measurement duration when the gyroscope is disposed at a corresponding plurality of rotational positions in the tool housing; and computing an azimuth of the wellbore from the plurality of gyroscope measurements.

A method for making gyroscopic azimuth measurements includes estimating a pitch angle and a roll angle of a gyroscopic surveying tool in a wellbore; determining a measurement duration for each of a plurality of gyroscope measurements from the estimated pitch and roll angles; making each of the plurality of gyroscope measurements at the determined measurement duration when the gyroscope is disposed at a corresponding plurality of rotational positions in the tool housing; and computing an azimuth of the wellbore from the plurality of gyroscope measurements.

A system and methods for drilling a well in a field having an previously drilled well are provided. In accordance with one example, a method includes drilling a new well in a geological formation having an previously drilled well using a bottom hole assembly (BHA) having a transmitter. The method also includes transmitting a signal while drilling using the transmitter of the BHA. Further, the method includes measuring from the previously drilled well the signal from the transmitter received by at least one optical fiber disposed within the previously drilled well.

An embodiment of a method for constructing a fracture network includes: receiving seismic data collected from a stimulation operation in an earth formation, the seismic data including seismic event data including a first seismic event associated with a first time increment and a second seismic event associated with a subsequent second time increment; and constructing a fracture network model. The model is constructed by: constructing an initial portion of the model based on the first seismic event; and subsequently updating the initial portion of the model based on the second seismic event.

A downhole device is provided that is intended to be co-located with an optical fiber cable to be found, for example by being fixed together in the same clamp. The device has an accelerometer or other suitable orientation determining means that is able to determine its positional orientation, with respect to gravity. A vibrator or other sounder is provided, that outputs the positional orientation information as a suitable encoded and modulated acoustic signal. A fiber optic distributed acoustic sensor deployed in the vicinity of the downhole device detects the acoustic signal and transmits it back to the surface, where it is demodulated and decoded to obtain the positional orientation information. Given that the device is co-located with the optical fiber the position of the fiber can then be inferred. As explained above, detecting the fiber position is important during perforation operations, so that the fiber is not inadvertently damaged.

Some aspects of what is described here relate to seismic data analysis techniques. A seismic excitation is generated in a directional section of a first wellbore in a subterranean region. Seismic responses associated with the seismic excitations are detected by a fiber optic distributed acoustic sensing array in a directional section of a second wellbore in the subterranean region. Seismic response data based on the seismic response are analyzed to identify changes in hydrocarbon saturation in a reservoir in the subterranean region. In some cases, the changes in hydrocarbon saturation are identified in real time during well system operations.

A method of estimating position of a borehole includes: disposing an acoustic sensor in a first borehole in an earth formation, the acoustic sensor including a plurality of measurement locations disposed along a length of the first borehole; drilling a portion of a second borehole in the earth formation using a drilling assembly; taking distributed acoustic measurement data over a time period during the drilling by the plurality of measurement locations, the acoustic measurement data based at least in part due to an acoustic signal generated by the drilling assembly and detected by the plurality of measurement locations; processing the measurement data to estimate a distance between the drilling assembly and the acoustic sensor; and controlling directional parameters of the drilling based on the distance.

A method of obtaining position of a downhole tool with respect to a wellbore includes logging well data via the tool over a period of time and measuring a lateral acceleration of the tool over the period of time with one or more accelerometers embedded in the tool. The method further includes performing double integration on an acceleration of the tool over a period of time. The method also includes obtaining a displacement of the tool over the period of time from the double integration. The method also includes fitting the displacement of the tool over the period of time to a best fit curve. The method also includes subtracting the best fit curve from the displacement of the tool over the period of time.

A method of obtaining position of a downhole tool with respect to a wellbore includes logging well data via the tool over a period of time and measuring a lateral acceleration of the tool over the period of time with one or more accelerometers embedded in the tool. The method further includes performing double integration on an acceleration of the tool over a period of time. The method also includes obtaining a displacement of the tool over the period of time from the double integration. The method also includes fitting the displacement of the tool over the period of time to a best fit curve. The method also includes subtracting the best fit curve from the displacement of the tool over the period of time.

The invention relates to gathering data about a hydrocarbon well by dropping a ball or dart (1) through the well (21) that emits an acoustic signature and/or senses information about the wellbore, such as deformation or bending. The dart signature and/or sensed data is communicated to the surface via a DAS cable (25) running down the tubing (20). The dart (1) may be made in two detachable modules, the first module (4) containing an acoustic emitter and the second module (6) having a certain drift diameter and being one of a set of interchangeable modules of different drift diameter that may be selected and assembled to the first module (4). The second module or both modules may be dissolvable. The dart (51) may store data as it descends through the tubing (60) and then dock with a docking station (65) that is connected with a TEC line (66) running up the outside of the tubing (60) and download the data via the TEC line (66) up to the surface.