Essar Oil plans to start drilling test well at Eastern Ranigunj CBM block in West Bengal by February 2008. The Directorate-General of Hydrocarbons (DGH) recently granted the company a fresh extension of six months to complete the drilling of core holes and 3D seismic under the phase-I of the work programme.

This is the second time since February-March, 2007 DGH granted extension to Essar to fulfill its commitments in CBM exploration in the block, awarded under the first round of CBM Policy.

Seismic Survey

"We are in the final stages of completion of phase-I of the work programme and now drilling the last (12th) core hole in the block. We will start drilling the test wells beginning February 2008," a company source said.

The company is slated to drill 15 test wells in the block. The location of the wells will be identified depending on the test results of the 'core' samples and 3D seismic. The seismic survey is carried based on technology alliance with Providence Technologies Inc of the US. The latter specialises in cross-bore seismic survey.

On drilling, Essar has already entered into a joint venture with Gardes Energy Services, US, specialising in under-balanced and horizontal multilateral drilling technology.

Drilling Techniques

Horizontal drilling aims at recovering methane trapped inside the coal seams over a larger area, compared with the conventional vertical well. In other words average production of a horizontal well far exceeds the vertical well, requiring lesser concentration of wells for producing the same amount of gas. Introduction of the technology, however, involves higher investments per well.

According to industry sources, such drilling techniques were a great success in the US and many other parts of the globe in the recent years. However, they feel that the technology is yet to be tested in Indian soil where the permeability of coal (described as gas content in the coal in common man's language) is lesser.