Last decade, more and more oil companies world-wide have used electromagnetic (EM) Operationss as a cost-effective, useful complement to seismic techniques.
Industry statistics proves that integration of these two independent Operationss remarkable reduces risk of drilling decisions.
Geological obstacles for seismic Operations, like volcanic rocks near the surface or in the section, dense limestone, and crystalline basement thrust over sediments could be resolved by EM Operations and contribute to final exploration success.
In many cases, like rugged terrain, jungle vegetation, and geographic remoteness, EM techniques can substitute seismic survey and provide wholly satisfactory results as from geological as well financial considerations.
Electromagnetic field parameters are very sensitive to changes in type of formation fluids and hydrocarbon saturation.
This allow successfully use HREM technique as for exploration, as well for appraisal, development, and production phases of hydrocarbons field life.
Main domains of HREM technologies applications in petroleum industry are following:
Detection of commercial accumulations of hydrocarbons in structurally complex subsurface
Plays and Leads prospectively ranking
De-risking drilling location decisions
Surveying areas where seismic and drilling are very expensive
Identifying channel sands and other stratigraphic traps with low acoustic impedance contrast
Locating reservoirs within thrust belt areas and volcanic drapes
Detecting Heavy Oil
Steam flood front monitoring
Detecting sequestered CO2
Gas storage monitoring
Technologies of high resolution electro magnetic survey (HREM) were used in a variety of geological and geographical conditions in various oil and gas basins. The experience of numerous study on producing fields shows that the oil deposits are marked clearly by positive anomalies of the Induced Polarization (IP), and gas deposits are associated with sharply reduced values of IP. These effects allow to use EM technique for prediction of type of hydrocarbons saturated reservoirs that with combination with seismic data significantly reduces the of drilling risks.
Regions of study:
Bahai sea, Sichuan Province, the Pacific Ocean shelf-slope, Province Huabey, Shengli sea
Do Mao Ping, Nan Men, Vauban Tee, Vulong Tee, Thiés Qiao, Gan Ning, Sun Zeng, Wu Bai Tu
The geographical conditions:
Ocean – 3 sites, Land area - 2 sites, Mountains -1 site, River - 2 sites
1. Sedimentary section, structural traps, oil, gas,
2.The carbonate reservoir, reefs, oil
3.Terrigenous section, clay reservoirs, volcanic interlayers, oil, gas
4.The upper part of the section, the sedimentary section of the continental slope, gas hydrates, gas Integrated Electro Magnetic technique
Integrated Electro Magnetic technique
1 TDEM- Inducted Induced Polarization (IIP)
2 TDEM - SSEF Secondary Seismic- Electric Effect
3 Induced Polarization Operations (IP)
The results of High-Resolution Electromagnetic Survey (HREM),
confirmed its efficiency in various geological conditions, high
economic profitability in the extreme surface conditions, which
allows to significantly reduce the risks of "dry" wells drilling.
Proved by drilling hydrocarbon deposits are clearly displayed by anomalies of IP, Rk and IIP parameters.
Control measurements on the structural highs of productive fields
have confirmed the high sensitivity of HREM technology to commercial
oil and gas deposits. This feature of the technology allows ranking
a plays with low and high concentrations of hydrocarbons.
Productive reef structure is clearly reflected in the parameters of the IP, Rk and IIP by local anomalies, significantly exceeding the background.
The possibility of a separate forecast of oil and gas deposits on the basis of integrated interpretation of seismic and EVR was confirmed.
On these results basis a ranking of prospects priority have been made. The recommendations for exploratory wells location were issued. Afterward drilling obtained commercial oil flows were obtained in 4 recommended wells and gas flow in one well.
Case study #1 South China sea, Vietnam