3D seismic surveys
Technical assistance – 3D Seismic technology
Since it has become harder to find new oil and gas fields, it is incredibly important to minimize the risks for drilling “dry” holes that not only have no benefit, but also are extremely expensive.
3D seismic technology is the most popular technology used today for finding and developing producing deposits. There are several companies that develop 3D seismic surveys that are then sold to the oil and gas industry. According to statistics, 60% of drilled wells should, based on 3D seismic surveys, result in producing fields. Previously, the success rate before 3D seismic technology was one out of ten fields.
A seismic survey means that low frequency sound waves are generated on the earth’s surface in order to find underground geological formations that may contain hydrocarbon. When the sound waves are sent through the earth’s crust, certain waves bounce upwards when the earth formations change character. Sensors at the earth’s surface then catch and register these reflected sound waves. Sound waves that are reflected from more shallow formations appear quicker than those that are reflected from deeper formations. An image is generated from this that shows the depth of the different formations and composition.
Compile and interpret geophysical data
Before a 3D seismic survey is done, the bedrock is hard to interpret since the geological formations are complex. A complex computerization of seismic data, which is complied into a transparent cube of the earth, is included in 3D seismic studies. The results from a 3D seismic survey are shown the same way as a magnetic x-ray shows medical results. The computer program presents a section of the bedrock with a clear computer image. The image is color-coded to indicate the most penetrable stratums, formation borders, faults and cracks. The 3D seismic surveys show where hydrocarbon reserves are located within an area and, through geological work, isolate the best drilling opportunity for locating these reserves.
Competition under the same conditions
When 3D seismic technology was new, usage was almost exclusively reserved for large multinational oil companies. They were the only ones with financial resources to invest in the then costly development and computer capacity. But as personal computers developed, became more powerful and less expensive, it also became possible for middle-sized oil companies to purchase the necessary computer capacity to carry out seismic surveys.
Today’s technology makes it possible for smaller oil companies to compete with larger companies since this technology makes it inexpensive to find oil. In addition, the technology makes it possible to scan older fields and locate reserves that couldn’t be detected previously. 3D seismic surveys are used to find, drill and develop thousands of small reserves that were missed through the years and previously considered too expensive to find and develop.
2D seismic image
A 2D seismic survey gives a cross-section of the bedrock. This technology was invented in the 1930’s and increased the probability of a successful drilling from 10 to 30 percent.
3D seismic image
3D seismic surveys was first used by independent oil companies during the 1980’s. This technology increased the probability for a successful drilling upto 70 percent.