Breakthrough Concept "Turning Hazards Into Resources, The Forgotten Play"

Isa, Mimi Lina; Kahar, Ruszaidi; Shahar, Suhaileen; Yu, Sheng Mou

Over the last three decades, the Malaysian exploration industry has matured significantly. Despite its maturity,new plays continued to be evolved and enable PETRONAS to play role supporting the government policies reducing dependency on oil as the main energy source. Recent discovery of a shallow gas accumulation in what was once considered a shallow drilling hazard to be avoided, has now become a new play promising substantial commercial gas resources. DS-1 has proven to be the largest shallow gas fields,producing gas at a depth as shallow as 512m MDDF. In addition several untested reservoirs,some of which yielded gas on MDTs were encountered. The shallowest interpreted gas reservoir occurred at a depth of 404 m MDDF. The discovery at DS-1 has given impetus and forced a relook at a forgotten play in Malaysia gas exploration history. The success had changed the overall exploration strategy in PETRONAS and enhances PETRONAS resources in meeting the demand of gas in Peninsular Malaysia.

DS-1 tested an east-west trending 4-way dip closure with high amplitude response on seismic and several have DHI's which appear flat and conformable with the structure closure. The flat events were interpreted as possible gas water contact (PGWC). In the past these high amplitudes were thought to be associated with low saturation gas diffused within the rocks as a result seal failure from the underlying field and as a result there was not much data acquired over the zone in conventional wells. However, the appearance of DHI's which were interpreted by the team to be PGWC led the team to convince its management that they represent actual gas accumulation and warrant a well to test the team's concept.

DS-1 was specifically drilled to evaluate possible commercially viable gas accumulation in several untested shallow reservoirs at depth ranging from about 350m to 900m below seabed. The well was located to target several of the brightest amplitude events mapped, which is channels or other sandstone bodies. Cutting samples and sidewall cores of DS-1 indicate the Lower Pliocene section to consist of slightly laminated very fine grained sandstones with dark streaks of carbonaceous material. The section was interpreted to be deposited in a tidal influenced coastal environment.Gas was discovered in seven reservoirs. Two production tests were conducted in the Lower Pliocene and Upper Miocene reservoirs respectively. The DS-1 was subsequently P&A as a commercial discovery.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013