For crosswell travel-time tomography, the sources and receivers are placed equally apart in the two wells with the boundaries on the left and right sides of the well. There are 11 sources in each well, and the sources are equally spaced. The Fermat principle is used to compute the observed data using a synthetic model. For this experiment, a synthetic model was developed. The model consists of the same parameters as the experimental one.
Modeling
Inverse problems in inverse geophysics are ill-posed, and the crosswell travel-time tomography problem is a prime example. The method uses a stabilizing functional to select a stable solution from a class of solutions, or from sharp boundaries, which may separate rocks with radically different petrophysical properties. The resulting models should resemble the true models in structure and size. A well-trained network can generate enhanced velocity and resistivity models.
Processes
To calculate the interwell raypaths of the Crosswell travel processes, the receivers and sources are placed in wells with equal spaces. Specifically, the source in well A is placed in the well B with 11 sources in each well. These data are computed using the Fermat principle. When these data are compared with actual observations, they are analyzed. This work helps understand the differences between the observed and synthetic data in crosswell travel processes.
Applications
Applications for crosswell travel have been discussed for many years but are only now moving beyond research into operational use. The main barriers to widening acceptance of this technology are its high cost and potential disruption of normal field operations. Fortunately, the costs of data acquisition are decreasing due to improvements in hardware and a growing experience base. Future improvements to data processing will limit the amount of disruption to field operations. In the meantime, crosswell technology is showing promise as a complementary technique to surface seismic and logging methods.
Costs
To estimate the travel time between two receivers in an interwell, first calculate the true travel time between the receivers in well A and B. Then, calculate the difference between the observed crosswell travel time and the raytraced crosswell travel time. These differences, known as errors, are then stored for each receiver pair. The process is repeated for each well, storing the raypath and travel times of each receiver pair in both wells.
Ray tracing
The mathematical technique of ray tracing can be used to simulate the crosswell travel of a particle. Ray tracing is an essential part of computer graphics, as it reduces the computational cost associated with the process. In the following sections, we will examine some of the key concepts in ray tracing. This article will focus on the first concept. A ray is a beam of light that is moving through a region of an unknown size, such as an empty space.
Downhole seismic sources
The primary use for downhole seismic sources is crosswell seismic tomography. The technique provides a 2D seismic image and velocity measurements. It has been applied in a variety of environments. However, the current methodology is limited by its limited accuracy. To ensure that the crosswell data is accurate, it must be well-calibrated using high-resolution x-rays from the source and receiver. For this, a new type of hydrophone is being developed.