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To investigate the corrosion behavior of gas-injection well of CO2 flooding and then to take measures to inhibit the corrosion of casing, firstly an HTHP autoclave and surface characterization technology are applied to analyzing the corrosion behavior of casing and then a new type of oil-based annulus protection fluid has been developed to avoid the casing corrosion issue. The results show that the casing in the simulated supercritical CO2-saturated aqueous brine phase (SC CO2-saturated aqueous phase) has severe uniform corrosion, while that in the simulated water-saturated supercritical CO2 (SC CO2 phase) has severe pitting corrosion. The temperature and CO2 partial pressure can promote the water film adsorbed on the steel surface, further inducing the corrosion of casing. In order to prevent casing corrosion, an oil-based annulus protection fluid suitable for gas-injection well in CO2 flooding is developed, and the preparation process of oil-based annulus protection fluid is proposed. The oil-based annulus protection fluid is composed of white oil and 1000 mg/L imidazoline inhibitor. The flash point of the oil-based annulus protection fluid is over 160 °C, the freezing point −23 °C, and the density 0.85 g/cm3. The corrosion inhibition rate is more than 80% when P110 steel is in SC CO2 phase with oil-based annulus protection fluid, and it is more than 95% when P110 steel is in SC CO2-saturated aqueous phase. It proves that the newly developed oil-based annulus fluid can effectively solve the corrosion problem of P110 steel as casing in gas-injection well of CO2 flooding.

Cytoplasmic diversification is of vital importance to avoid the genetic vulnerability of hybrid rice (Oryza sativa L.). A new indica cytoplasmic male sterility (CMS), designated African rice (AF) CMS, has been derived from interspecific crosses using African rice (Oryza glaberrima Steud.) as the cytoplasmic donor and genetically characterized for its potential use. The AF CMS lines were completely sterile whereas the fertility of its F₁ hybrids was readily restored. The restoration–maintenance relationship of AF CMS was consistent with that of sporophytic wild abortive (WA) and Indonesian paddy (ID) CMS but different from the gametophytic Honglian (HL) CMS. Specific banding patterns for AF CMS were identified by amplified fragment length polymorphism (AFLP). The AFLP markers can be used to detect genetic purity of seed stocks of AF CMS lines and their hybrids. Fertility segregation in F₂ populations of crosses between AF CMS lines and an introgression restorer line corresponded to a 3:1 fertile:sterile ratio, indicating a single major dominant restorer gene was involved. The fertility-restoring gene was located on chromosome 10 between simple sequence repeat (SSR) markers RM304 and RM6100 at a genetic distance of 1.25 cM from RM6100. Molecular assays confirmed the introgression of a major restorer gene from O. glaberrima into the O. sativa genome. We conclude the new AF CMS system should be of great potential use in hybrid rice production.