Timor Leste
Regional Trap Integrity Prediction Study
Regional Trap Integrity Prediction Study
Blessed with abundant evidence of effective source rocks, productive reservoir sequences and plenty of structural traps the offshore region has enjoyed significant past success for both oil and gas. Explorers have also experienced much failure, with a high proportion of dry holes, commonly attributed to trap breach during Tertiary fault reactivation (53%) or failure to drill a valid structure (34%) related to poor seismic imaging.
Effective trap definition, primarily due to to poor seismic data quality hampering imaging of fault-structure at the target depth, is increasingly being addressed by advances in seismic acquisition and reprocessing techniques that provide explorers the tools to overcome one of the main reasons for past failure. Loss of hydrocarbons due to Neogene fault breach accounts for more than half of the dry holes, making improved mitigation of this risk critical to the delivery of future discoveries and avoidance of traps with a high pre-drill risk of trap breach. Collectively, a reduction in both key risks will lead to a better appreciation of the yet to find potential and deliver a boost to future exploration outcomes.
Critical to future success is understanding the failures to build better predictive models that can be calibrated against previous results, both success and failure. A conventional play-based exploration approach is not effective in this setting and leads to poor choices on which opportunities to mature, that will ultimately lead to more dry holes.
The issue of poor trap integrity related to Neogene fault reactivation is widely recognised as a key risk that has blighted exploration success rates across the region and continues to strongly polarise chance of success for yet to be drilled leads and prospects. A variety of methods like contemporary stress field analysis, fault orientation or modern seepage response have been employed to better manage this risk. Results showed promise, but a retrospective look-back success not exceeding 50% made it difficult to demonstrate the necessary confidence to support future exploration decisions.
Research initiatives at the National Science Agency CSIRO in the late 1990s to early 2000s undertaken to address trap breach risk, initially focussed on methods to confidently identify traps that once contained oil and had been fully breached or to define the proportion of leakage in traps that still contain a live column. This work defined the extent of the problem, but subsequent pioneering structural analysis of fault patterns by the CSIRO team, calibrated using data that had been acquired on the Laminaria and Corallina oil fields, offered a solution that, for the first time, provided genuine predictive capability. Known as strain localisation, the method recognised that some trap forming faults preferentially accrue more deformation during widespread Neogene fault reactivation, and as a result become more prone to breaching. These observations highlighted a key control on the probability of trap breach, yielding a better match with the prior drilling results than other methods of the time. Despite this success the method was not widely employed and research in this area was discontinued.
The issue of poor trap integrity related to Neogene fault reactivation is widely recognised as a key risk that has blighted exploration success rates across the region and continues to strongly polarise chance of success for yet to be drilled leads and prospects. A variety of methods like contemporary stress field analysis, fault orientation or modern seepage response have been employed to better manage this risk. Results showed promise, but a retrospective look-back success not exceeding 50% made it difficult to demonstrate the necessary confidence to support future exploration decisions.
Research initiatives at the National Science Agency CSIRO in the late 1990s to early 2000s undertaken to address trap breach risk, initially focussed on methods to confidently identify traps that once contained oil and had been fully breached or to define the proportion of leakage in traps that still contain a live column. This work defined the extent of the problem, but subsequent pioneering structural analysis of fault patterns by the CSIRO team, calibrated using data that had been acquired on the Laminaria and Corallina oil fields, offered a solution that, for the first time, provided genuine predictive capability. Known as strain localisation, the method recognised that some trap forming faults preferentially accrue more deformation during widespread Neogene fault reactivation, and as a result become more prone to breaching. These observations highlighted a key control on the probability of trap breach, yielding a better match with the prior drilling results than other methods of the time. Despite this success the method was not widely employed and research in this area was discontinued.
The new Ascendience study drew together the key researchers from the earlier CSIRO study to integrate these research results with industry common workflows and extend the initial work across the entire Offshore Timor Leste acreage release and extending into neighbouring Australian territory. A new holistic enhanced predictive model was developed to confidently identify intact traps, assess the degree of fill to produce more accurate volumetrics and aid well placement to improve the likelihood of exceeding minimum economic field size requirements. Calibration of the model against the drilled oil fields showed it to be an effective tool to risk undrilled traps, with the method successfully calibrated on the proven oilfields, being 100% effective for commercial oilfields.
Wells with defined palaeo-oil columns or residual oil columns beneath current OWCs also yielded good adherence with the model predictions of close to 70%, much higher than that achieved using other published predictive methods that rely on stress field analysis or oil seepage surface indications.
Armed with the most successful predictive model ever produced for the region, the 2021 Ascendience multi-client study includes assessment of a portfolio of more than 200 undrilled leads and prospects from across Offshore Timor Leste. Fifty of the largest undrilled opportunities were ranked by risk of trap breach, with 60% of these features, each with volume potential above the minimum economic field size for the basin and up to > 300 MMbbls for the largest lead, had either low or moderate trap breach risk. The geographical spread of these attractive leads delivered clear insights into the blocks offering the greatest potential for future success.
The regional fluid history atlas compiled as part of the Ascendience study also reveals more regional charge access for oil, extending well away from the proven oil fairway and bringing much of the offshore region into play. Wide swaths of open acreage covered only by legacy 2D seismic data, mostly acquired through the 1990s offer great potential for this attractive lead inventory of low and moderate ranked traps to be matured by application of modern seismic reprocessing and acquisition of targeted new 3D where applicable. New leads, prospects and previously unrecognised plays all with access to a proven petroleum system are likely to result from renewed exploration effort.
Exploration upside, beyond the current focus areas, has the potential to provide new players the required materiality and opportunity diversity to allow serious consideration of current farm-in opportunities or future new acreage offerings from the Timorese regulator, Autoridade Nacional do Petróleo (ANP Timor Leste). Together with our study partners from Discover Geoscience and Searcher Seismic we can offer new entrants the basis for assessing attractive acreage in Timor Leste by combining an extensive regional study and play-based assessment with the Ascendience trap integrity study to supercharge your understanding of your farm-in options.
Aside from clear application to petroleum prospectivity, the work undertaken by Ascendience Geoscience also contributes to a better understanding of leakage risk for planned CCUS projects and allows options such as bringing Sunrise to Southern Timor via sub-sea pipeline to be more effectively assessed from a geotechnical risk perspective. As an independent product, learnings from the Ascendience study offer critical data to more effectively address key risks and manage stakeholder engagement.
The Ascendience Timor Leste Trap Integrity study, priced from $USD 40,000, is available for purchase exclusively through our project commercial partner, Searcher Seismic.
Already licenced by major companies operating in Timor Leste, this study offers the chance to more effectively screen opportunities and delivers outstanding value to address key risks. Together, Ascendience and Searcher Seismic bring unparalleled experience on Offshore Timor Leste prospectivity and in conjunction with our partner products and affiliate network we can fully assist with all aspects of sub-surface evaluation and portfolio build to ensure the study results translate into maximum value creation.
Contact us today for more information on this game-changing technical study and profit from our experience.
