How can you evaluate subsurface rock formations for drilling engineering?

1 Geophysical logging

Geophysical logging is the process of measuring various physical properties of the rock formations along the wellbore using specialized instruments or tools. These properties include resistivity, porosity, density, sonic velocity, gamma ray, and neutron capture. By analyzing the geophysical logs, you can infer the lithology, fluid content, pressure, temperature, and stress state of the rocks. Geophysical logging can be done during or after drilling, depending on the type of tool and the objective of the measurement.

2 Core analysis

Core analysis is the process of examining and testing the cylindrical samples of rock that are cut and retrieved from the wellbore during drilling. These samples are called cores, and they provide direct information about the rock's structure, composition, texture, porosity, permeability, strength, and fracture characteristics. Core analysis can be done at the wellsite or in a laboratory, using various techniques such as visual inspection, microscopy, X-ray diffraction, scanning electron microscopy, and rock mechanics tests.

3 Well testing

Well testing is the process of flowing fluids from the wellbore to the surface and measuring the pressure, temperature, and flow rate responses. These responses reflect the dynamic behavior of the reservoir and the interaction between the wellbore and the rock formations. Well testing can be done during or after drilling, using different methods such as drill stem testing, wireline formation testing, or production testing. By analyzing the well test data, you can estimate the reservoir pressure, permeability, skin factor, and productivity index.

4 Numerical modeling

Numerical modeling is the process of simulating the physical processes and phenomena that occur in the subsurface using mathematical equations and numerical methods. These equations represent the conservation of mass, momentum, energy, and chemical species in the rock-fluid system. Numerical modeling can be done before, during, or after drilling, using various software tools and input data from geophysical logging, core analysis, well testing, and other sources. By performing numerical modeling, you can predict the reservoir performance, wellbore stability, fracture propagation, and fluid flow.

5 Integration and interpretation

Integration and interpretation is the process of combining and synthesizing the data and results from different sources and methods to evaluate the subsurface rock formations for drilling engineering. This process requires a multidisciplinary approach and a comprehensive understanding of the reservoir geomechanics and rock failure. Integration and interpretation can be done at any stage of the drilling project, using various tools such as crossplots, maps, charts, graphs, and reports. By doing integration and interpretation, you can identify the key factors and parameters that affect the drilling operation and optimize the drilling design and execution.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?