These first reserves estimates are for the Oligocene OS II horizon primary target in this portion of the Cambay Field, known as the Western High, the Perth-based company said.
“The first estimates of hydrocarbons in place have been completed and additional work is ongoing to define with a higher level of confidence the characteristics of the reservoir and the fluid composition,” Oilex managing director Bruce McCarthy said.
“On the basis of data analysed from existing wells, the wells have been optimally located to intersect the possible oil leg of the western high structure.”
Last week, Oilex announced it had increased its participating interest in the Cambay Field to 45% from 30%, as part of a transaction involving two other small fields. The acquisition of the additional 15% interest is subject to approval from the Indian Government.
More than 60 wells have been drilled on the Cambay Field since its discovery in 1957. Most of these wells were shut in for extended periods of time due to sand or water incursion or down-hole equipment problems. However, a small number of wells are still producing oil on an intermittent basis.
To gain a better understanding of the field, Oilex said the joint venture would undertake drilling operations before considering its redevelopment options.
Oilex will act as operator for the drilling program, which has been separated into two phases for logistic reasons due to the monsoon season between mid-June and October. In the first phase, two or possibly three wells are planned for drilling on monsoon pads starting in early June.
Oilex, which said it has sufficient capital to fund its share of the first phase, is also looking at acquiring a 3D seismic survey over the western part of the block to start in late May and to be completed during a 15-20 day gap before the monsoon season.
The second part of the 3D seismic survey will be acquired over the eastern half of the block after the monsoon season, McCarthy said.
“The advantage of this phased program is that well and seismic data will be available for refining seismic coverage and well locations prior to the commencement of the second phase of work, post-monsoon,” he said.
“Modern well data including wireline logs, formation pressure and fluid characteristics will be acquired during drilling and used to normalise the existing data set, which has been digitised and correlated across all available wells.”
Mapping – based on wireline correlations of notable stratigraphic markers – has been used to select the well locations for the first phase of drilling.
“The structure of particular interest in the western part of the block is a north-south trending faulted anticline, along which many old wells have produced oil and gas or have strong indications of oil and gas in good quality reservoirs, albeit in relatively low volumes,” McCarthy said.
“Reservoir rocks occur throughout the Tertiary section in the Eocene, Oligocene and Miocene and these intervals will be evaluated thoroughly by the first phase wells.”
He said these sandstones were proven producers in fields immediately north and south of the Cambay Field.
