EAGE Workshop on Unlocking Carbon Capture and Storage Potential

With so little geological information available in traditional overburden section, legacy cuttings from oil and gas wells have an important role to play as the need to store CO2 in the subsurface becomes more urgent. Here, examples from the Triassic Bunter Sandstone, UK, are shown to illustrate how cuttings can assist with the prioritization of certain structures and formations for CO2 storage, as well as offering insights into problems associated with CO2 injectivity, formation damage and potential leakage.

A method of rapidly and cost-effectively screening fairways is presented which maximises the use of any available data, and helps to high grade fairways for further assessment. First, a regional-scale screen to prioritise basins for further study is completed. Spatial datasets are used which consider parameters including the ability for a basin to host supercritical CO2, along with indicators of structural complexity, dominant paleo-depositional environment in the optimal target interval, and potential economic considerations.

In prioritised basins key stratigraphic intervals are defined, and CCS fairways characterised. The method generates reservoir-seal pairs from regional gross depositional environment maps, which are combined with reservoir depth, and suggested areas of structural complexity as indicated by tectonic events. Potential economic constraints, like distance to specified infrastructure, are also utilised to highlight where parts of the fairway could be less feasible. Each fairway is also assessed for a range of subsurface parameters to provide a relative index of CCS suitability. Finally, storage resource estimates for the fairways can be calculated from subsurface storage volumes using a CO2 density and storage efficiency factor, and classified in the SPE CO2 storage resource management system.

With the need for rapid growth of the CCS industry, practitioners will need to rely on modeling and simulation, rather than analogs, to further understanding. Saturation functions are some of the critical inputs in reservoir simulation to prediction the dynamic behavior of the CO2 migration in the subsurface. As estimates of CO2 plume size, during and post-injection, influence land acquisition and monitoring, measuring, and verification (MMV) plans, it is important to use high quality experimental data and to properly work up the data to be used in a reservoir simulator. The work presented here adapts the methodology that ExxonMobil developed for saturation function inputs for reservoir simulation of oil and gas production to CO2 injection into a saline brine aquifer. We also present guidance on expected ranges for relative permeability Corey exponents (Corey, 1954) for CO2/brine based on literature data the we processed using the methodology presented here. From our decades of experience of using reservoir simulation to make business decisions, this approach properly represents the displacement physics leading to more accurate performance prediction and history matches.

Monetization of significant hydrocarbon resources in Malay basin is locked owing to high carbon dioxide (CO2) contamination. Also to realize PETRONAS target to reduce overall GHG emission, carbon capture and storage (CCS) has emerged as the leading option. To ensure safe and permanent subsurface storage of CO2, robust screening and selection of storage sites has been identified as the key enabler. CO2 storage in depleted hydrocarbon reservoirs is considered as the most suitable option because of its proven trapping mechanism, abundance of data enabling thorough analysis for containment, capacity and injectivity.

This paper presents results of subsurface screening in order to select a depleted gas clastic field having more than 40 years production from 20 infill wells in Malay basin for CO2 storage. Field A is a 4-way dip closure with gas and condensate reservoirs occurring from the Tertiary Tapis to Pilong formation. Medium fault density and E-W, sub N-S faults are seen from seismic. Reservoir groups are comprised of sequences deposited tidal dominated fluvial, shallow marine, deltaic and coastal depositional environments. Subjected to integrated subsurface evaluation and project risks assessment, its storage plan has been endorsed with detailed MMV planning is ongoing.

In this study we conducted Pore Pressure analysis, 1D geomechanics, Fault Stability and Caprock Integrity Analysis in Pliocene-aged Cisubuh Formation to obtain the maximum allowable pressure in the Cisubuh Formation when CO2 is injected into the Parigi Formation’s saline aquifer. Pore Pressure and 1D Geomechanics are using data from wireline logs, well tests, mud logs, drilling fluids and triaxial tests. MICP analysis of cutting drilling use to analyze the fault Stability and Caprock Integrity Analysis. Fault Stability Analysis and Caprock Integrity Formation using MICP from cutting is the first investigative report in Indonesia for Carbon Capture Storage interest.

The Illinois Storage Corridor project plans to mitigate CO2 emissions from multiple industrial sources in two large-scale underground storage sites. The CO2 will be sequestered around 3580 ft (∼1091 m) below the surface in a saline sandstone aquifer known as St Peter Sandstone, southern Illinois, US. The current development plan for the Illinois CarbonSafe Prairie project is to inject 8.125 million tons per annum of CO2 for a period of 20 years into the Ordovician St Peter and Everton saline sandstone formations. This paper discusses the technical steps that were taken to outline a fit-for-purpose Monitoring, Measurement and Verification (MMV) plan to address the identified risk factors of a CO2 injection operation.

Understanding the well integrity of the legacy wells is one of the critical aspects to ensure success and integrity of CO2 storage. Improper well abandonment and well design can be potential leak path which can jeopardize the integrity of the CO2 storage.

The study will focus on well’s plug and abandonment method, whether it comply to 2 barriers requirement. Then, to identify whether the well have been used to conduct well test assessment, as this may affect the casing temperature deration, especially if the bottom hole temperature is above 225-degree Fahrenheit. Next, to identify whether the casing across the injection zone is chrome material which is resistance to CO2 corrosion. Lastly to check on the cement integrity by checking the cement type, cement length, cement verification, for both cement plug and cement behind casing across caprock and above CO2 injection zone.

In this study we presented several examples of potential usage of S-DAS. Due to the CCS business model and the requirement to verify containment and conformance through the pre-injection, injection and post-injection phases of the CCS project, is critical that we re-evaluate implementation of methods currently used to provide time-lapse data, in particular time-lapse seismic data. We summarize the experience gained on different aspects of S-DAS seismology through field experiments conducted over the last few years. We will present both marine and land examples and cover both passive and active recordings. The critical learnings from these field experiments are placed in the context of developing a holistic cost-effective monitoring strategy for CCS, with discussion on upcoming activity and critical milestones.

In response to Thailand’s commitment to reduce greenhouse gas emissions by 40% and PTTEP’s ambition to reduce its greenhouse gas emission intensity by 30% in 2030, a screening and storage identification study was conducted to identify geological storage targets in Thailand. Our maturing offshore gas field has been identified as the first geological storage target, and since then, more detailed storage assessments have been conducted through a collaborative effort between our corporate and asset teams. In the assessment study, we have constructed an integrated dynamic-geomechanics-geochemical model using comprehensive and systematic workflows to optimize storage capacity without compromising reservoir injectivity and containment integrity. The results have now been passed to our well engineering and surface facility engineering teams for further evaluation. Simultaneously, we are engaging in communication with partners and regulators to obtain the necessary approvals to proceed with the first geological CO2 sequestration project in Thailand.