• Energy Research

In this paper, the immiscible water-alternating-CO2 flooding process at the LH11-1 oilfield, offshore Guangdong Province, was firstly evaluated using full-field reservoir simulation models. Based on a 3D geological model and oil production history, 16 scenarios of water-alternating-CO2 injection operations with different water alternating gas (WAG) ratios and slug sizes, as well as continuous CO2 injection (Con-CO2) and primary depletion production (No-CO2) scenarios, have been simulated spanning 20 years. The results represent a significant improvement in oil recovery by CO2 WAG over both Con-CO2 and No-CO2 scenarios. The WAG ratio and slug size of water affect the efficiency of oil recovery and CO2 injection. The optimum operations are those with WAG ratios lower than 1:2, which have the higher ultimate oil recovery factor of 24%. Although WAG reduced the CO2 injection volume, the CO2 storage efficiency is still high, more than 84% of the injected CO2 was sequestered in the reservoir. Results indicate that the immiscible water-alternating-CO2 processes can be optimized to improve significantly the performance of pressure maintenance and oil recovery in offshore reef heavy-oil reservoirs significantly. The simulation results suggest that the LH11-1 field is a good candidate site for immiscible CO2 enhanced oil recovery and storage for the Guangdong carbon capture, utilization and storage (GDCCUS) project.

The Qiongdongnan Basin, located off Hainan Island, South China, is a petroliferous basin containing what is currently the largest offshore-producing gas fi eld in China (YA13-1). This paper evaluated the potential of CO 2 storage in the Qiongdongnan Basin to provide background data on CO 2 storage capacities for regional planning purposes. Four regional seals and high-quality reservoirs exists in the basin, in mostly marine sequences. The estimated mean effective CO 2 storage capacity of the basin is 41 Gt CO2 , determined from published data and the Carbon Sequestration Leadership Forum methodology for assessing oil and gas storage capacity; the majority of the storage capacity is in saline formations and oil and gas fi eld (15 Mt CO2 and 832 Mt CO2 , respectively). The prospective areas for CO 2 storage in the Qiongdongnan Basin are in the belts of the Northern Depression and the Central Uplift. The Yacheng Uplift, as the most favorable area for CO 2 storage, contains the YA13-1 gas fi eld, which has an estimated mean effective CO 2 storage capacity of 73 Mt CO2 . The Qiongdongnan Basin may provide storage sites for CO 2 stripped from the CO 2 -enriched gas from the basin itself, or from the emission sources in Hong Kong and Guangdong Province. However, industrial development on Hainan Island is weak, as the island was defi ned as an 'island for international tourism' by the Chinese govern- ment in 2009. The feasibility of transporting CO 2 to storage sites in the Qiongdongnan Basin using the pipeline now transporting gas from the YA13-1 gas fi eld to Hong Kong should be explored. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd

AbstractThe Pearl River Mouth Basin (PRMB) is the largest petroliferous sedimentary basin in the northern South China Sea. It is near the coastal economic zone of Guangdong province where a large number of CO2 emission sources are located. Carbon dioxide enhanced oil recovery (EOR) represents an opportunity to promote offshore carbon capture, utilization and storage (CCUS) deployment because CO2 flooding offers a method to recover additional oil while simultaneously sequestering anthropogenic CO2. In this paper, a comprehensive multiparameter ‘quick look’ and potential evaluation method was proposed to screen and assess offshore CO2 EOR potential. A screening scheme for the CO2 EOR potential of reservoirs of the PRMB was also proposed using additional parameters, including reservoir properties and engineering design incorporating a dimensionless screen model and calculations. The results show that the suitability of reservoirs for CO2 EOR and storage varies and could be categorized into four priority grades. Approximately 30 of the oil reservoirs from 10 oilfields were preferentially identified by applying the screening method for reservoirs with predicted higher ultimate recovery potentials. It was predicted that 3227 × 104 t of additional oil could be produced from these reservoirs and that 3617 × 104 t of CO2 could be simultaneously stored. The sensitivity analysis shows that injection pressure (Pinj) would be more sensitive than production pressure (Pp) and well distance (L) on the CO2 EOR and storage efficiency, indicating that EOR operations with higher Pinj may improve oil production. The prospective reservoirs include those candidates with suitability grades of I and II from the Lufeng (LF) and Huizhou (HZ) oilfield clusters, where 1164 × 104 t of additional oil could be produced and 1464 × 104 t of CO2 stored with CO2 EOR. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

AbstractThe South China, especially Guangdong Province, as the most developed area of China emitted large CO2 from energy consumption and industrial production, actively advocates low-carbon development strategies. As an effective option to reduce CO2 emissions, CCS is potentially an effective option to reduce CO2 emissions to low-carbon economy development of South China, especially to Guangdong province. The CO2 storage potential in sedimentary basins onshore South China is limited as previous indicated. So the potential of sub-seafloor CO2 storage in offshore basins would be important. According to the assessment in this paper, large sedimentary basins offshore in the northern SCS have huge CO2 storage potential. Miocene deltaic, coastal plain, and neritic clastic rocks in these basins contain high-porosity and high-permeability aquifers and excellent seals. The estimated effective storage capacity, which is 2.6% of the theoretical capacity, is ∼300 GtCO2 in PRMB, ∼57 GtCO2 in BBGB, ∼41Gt CO2 in QDNB and∼160Gt CO2 in YGHB. On the whole, the Tertiary sedimentary basins in northern SCS margin have large storage capacities of abut 567Gt CO2, which provide a promising storage option for CCS implementation in South China. As the high costs is a major obstacles for sub-seafloor CO2 storage, the reuse of infrastructures for oil and gas development, such as platforms, wells and pipelines, would be the first choice. Although the theoretical storage capacities of the offshore oil and gas fields in the northern SCS are small, they distributed as groups and clusters and associated with sufficient quantified CO2 storage capacity in the saline aquifers. Further assessments are needed to define the residual life (= equipment life minus the field life) of the infrastructures, their practical and matched storage capacities, as well as a proper character and site screening particularly in regard to containment and risk of leakage. All these have been done well ahead of the real abandons of the oil/gas fields, so that the fields are in “CO2 Storage Readlines (CSR)”.

CCS (Carbon Capture and Storage) is the only technology available to achieve a deep cut in CO2emissions from large-scale fossil fuel usage. Although Guangdong Province has less heavy industries and higher reliance on energy import compared with many other provinces in China, CCS is still essential for the low-carbon development in the province. This is because fossil fuel energy is now and will be in the foreseeable future the major energy in Guangdong. CCS may have other benefits such as helping energy security and bring new business opportunities. The feasibility of CCS development in Guangdong is ensured by the existence of sufficient CO2storage capacity in offshore sedimentary basins in the northern South China Sea. A safe CO2storage is achievable as long as the selection of storage sites and the storage operations are in restrict quality control. The increased cost and energy penalty associated with CCS could be reduced through technical R&D, the utilization of captured CO2, and the utilization of infrastructure of offshore depleted oil fields. Fossil fuel energy plus CCS should be regarded as a new type of clean energy and deserves similar incentive policies that have been applied to other clean energies such as renewables and nuclear.

Abstract CO2-enhanced oil recovery (CO2-EOR) and storage is currently the most effective and economic technology for reducing CO2 emissions from burning fossil fuels in large scale. This paper is the first effort of proposing a modelling assessment of CO2-EOR and storage in the HZ2-1 oilfield in the Pearl River Mouth Basin in northern South China Sea offshore Guangdong Province. We attempt to couple the multi-parameter dimensionless quick screening model and reservoir compositional simulation for optimization of site screen and injection simulation. Through the quick screening, the reservoirs are ranked by EOR dimensionless recovery RD, and by CO2 storage in pore volume SCO2. Our results indicate that SCO2 is highly pressure dependent and not directly related to RD. Of these reservoirs, CO2-EOR and storage potential of the M10 was estimated through a compositional simulation as a case study based on a 3D geological model. Nine scenarios of CO2 injection operations have been simulated for 20 years with different well patterns and injection pressures. The simulation results represent an obvious improvement in oil production by CO2 flooding over No−CO2 production. The best operation for M10 is miscible CO2 flooding, which led to the higher recovery factors of 52%˜58% and CO2 stored masses of 8.1×106˜10.8×106t. The optimum operation for CO2 injection should be set well pattern in region of injector I1 and high injection pressure for miscible flooding. In a whole, the HZ21-1 field can be used as a candidate geological site for GDCCUS project. We are fully aware of the limitation in the primary modelling including reservoir and fluid properties and production history matching, and regard this study as a general and hypothetic proposal.

Abstract Strategic regional planning is an important step towards a successful CCUS development. This paper is the first effort of proposing a development plan of offshore CO2 storage and transport for Guangdong in 2030 and 2050. We attempt to make an ambitious and achievable plan. The cluster-hub model of sources and sinks is adopted, and reuse of existing infrastructures is preferred. The targets of CCUS in Guangdong by 2050 are approximately 8% of the CCS targets that proposed for entire China (ADB, 2015), except a smaller target of 2050. The dual-phase and dual-track approach of ADB’s roadmap is followed. The CCUS phase I before 2030 is characterized by the capture of high-purity CO2 from petrochemical industry and the storage of CO2 mainly related to CO2-EOR. The target of ∼3 Mtpa CCUS in 2030 will be achieved by source-sink match A1. The phase II from 2030 to 2050 is characterized by a wider deployment of CCUS. The target of CCUS in Guangdong is ∼35 Mtpa in 2040 and ∼110 Mtpa in 2050, leading to the cumulative CO2 avoidance of ∼187 MtCO2 for 2031–2040 and ∼730 MtCO2 for 2041–2050. Four source-sink matches are proposed for this phase, including the storage clusters in the Pearl River Mouth Basin and in the Beibuwan Basin in the northern South China Sea. Research with sufficient lead time to support the phased CCUS development is proposed, including databases, feasibility studies, technique R&D, cost estimation, and optimized system design. We are fully aware of the large uncertainty in the years ahead, and regard this planning as a highly general and hypothetic proposal.