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This paper presents a novel alcoholic acid system to remove the damage caused by frac fluid in tight gas reservoir. Damage resulting from hydraulic fractures takes two distinct forms: damage inside the fracture itself because of inadequate breaking of the fracturing fluid polymer; and fracture-face damage because of excessive leak-off. The objectives of laboratory experiments are to identify potential damage and aid selection of the optimum treatment fluid and design. A novel alcoholic acid flow tests illustrated the permeability increased because of pore & throat enlarged by using mercury intrusion experiments. It was critical in addressing issues of selection of fracturing fluids, polymer concentrations and breakers. Improved breaker systems show even greater benefit when used in conjunction with the lower loading polymer systems. The newer fluid systems enhance load recovery and reduce formation exposure to potentially damaging polymer residue. DB gas reservoir is a low porosity, low permeability reservoir in the northwest of China. Large scale of hydraulic Fracturing has been carried out as effective method to get high gas production rates. However, the gas production rate after treatment increased to 335,683m3/d, and then declined to 34,875m3/d rapidly. The skin factor from well testing after hydraulic fracturing was 112, which indicated fractures and formation may appear damaged seriously because of more than 60% of the load fluid can be invaded and trapped in the formation by entering the smaller capillary pores during higher injection pressures. The gas production rate recovered from 32,383m3/d to 301,374m3/d and kept constantly by using treatment method of a novel alcoholic acid system.

Microscopic examination of Spodoptera litura(SL-1) cell infected with AcMNPV or SfaMNPV revealed progressive cell blebbing starting at 8 h-12 h postinfection and culminating in total cell destruction at 24 h postinfection. The fragmentation of the infected cell nuclei was observed by stained with the specific fluorescent dye DAPI. Agarose gel electrophoresis analysis of the DNA extracted from infected cells show typical DNA ladder. All these supported that both viruses infected SL-1 cells undergo apoptosis. Through lipofectin transinfection, we observed that only the DNA of AcMNPV or SfaMNPV can also induce apopotosis of SL-1 cell. Virus titer analysis revealed that neither viruses can duplicate in SL-1 cells.

Atg8 proteins fused with tags are commonly used to detect autophagy. The expression patterns of Lepidopteran insect Atg8 are relatively well documented. However, the influence of protein tags on characterization of Atg8 is still not very clear. Our results showed that endogenous Spodoptera litura Atg8 and HA tagged Atg8 driven by the baculovirus ie2 promoter were enriched in cytoplasm. The recombinant plasmid pEGFP-Atg8(EGFP) in which Atg8 contained a stop codon was constructed and expressed. Green fluorescence was accumulated in cytoplasm. However, red fluorescence was located in both cytoplasm and nucleoplasm in most cells transfected with the recombinant plasmid pmCherry-Atg8(EGFP). In contrast to pEGFP-Atg8(EGFP), green fluorescence was also located in both cytoplasm and nucleoplasm in most cells transfected with the recombinant plasmid pie2/EGFP-Atg8 driven by the baculovirus ie2 promoter in which the CMV promoter and EGFP nucleotide sequences were removed, and the high level of the EGFP-Atg8 expression significantly increased its abundance in nucleoplasm. HA-Atg8 expressed at high level through baculovirus under the control of polyherin promoter was also localized in cytoplasm and nucleoplasm. The cleavage of mCherry-Atg8 was different from that of EGFP-Atg8. Both the mutant mCherry-Atg8F77/79A resulting in non-cleavage of the Atg8 and the mutant mCherry-Atg8G exposing its glycine residue at the end of C-terminus were also localized in cytoplasm and nucleoplasm. The increase of autophagosomes decreased the abundance of mCherry-Atg8 in nucleoplasm. In addition, the ratio of HA-Atg8-PE/HA-Atg8 was less than that of endogenous Atg8-PE/Atg8. These results demonstrated that the Atg8 is located in both nucleus and cytoplasm when expressed at high level and exported to the cytoplasm when autophagy is activated, and the fusion tags of Atg8 might have influence on the processing of Atg8 fusion proteins.

Abstract The Taklimakan is the second largest desert in the world; the TaZhong oilfield is located in the Taklimakan Desert heartland. The Ordovician carbonate is one of the producing zones of TaZhong field. Acid fracturing has been normal for stimulating wells in these carbonate formations. The freshwater prepared for fluid and acid was conveyed 300 kilometers far away from TaZhong oilfield in the early construction, a lot of money and time was spent on transportation. However, there is superficial saltwater at a depth of tens of meters under the desert, and this paper will provide the technology of reducing freshwater consumption by using shallow saltwater for pad fluid in acid-fracturing. First, this paper presents a brief developed history of TaZhong oilfield and the characteristics of Ordovician formation. In major, this paper introduces the study and case of Taklimakan desert superficial saltwater fracturing fluid, including the shallow water salinity tests and the problems of shallow water fluid, solutions for stable fluid and the performances of superficial saltwater fluid, such as the stability of saltwater fluid, rheology, and gel breaking and injures. Final, a field example of acid fracturing used shallow water fluid is included, and the responses of treating pressure are analyzed. This work has helped prove the shallow saltwater in the desert of TaZhong oilfield which is feasible for service in acid-fracturing treatment oprations, a result has been established that a reliable fracturing fluid with good performance is wide used recent years. Because of the technology of superficial water fracturing fluid, an acid fracturing treatment well time saving is 2 to 3 days, and the transportation cost saving was considerable. Introduction The depth of the Ordovician formations is 4000m-6000m, and the temperature is from 110? to 150?. The natural fissures and vugs are major hydrocarbon reservoirs because of the low matrix porosity (2%-5%) and low permeability. Acid-fracturing is the main stimulating treatment in TaZhong carbonate, such as pad acid fracturing or multi-alterenative acid fracturing. Water based hydroxipropil guar fluids are generally used for preflush, and several acids are applied during treatment, such as gel acid, surface-crosslinked acid, emulsified acid and VES acid. Recent years, further development of the field had been achieved with well stimulations, increasing production rates, over a hurdred of wells were treated by acid fracturing and more than twenty wells were treated by hydraulic fracturing or sand fracturing with surface-crosslinked acid. This has led to increase freshwater consumption for these oprations, in order to save freshwater sources and conveyance costs, the field employers have to find alternatives to reduce the fresh water consumed, the shallow saltwater under the Taklimakan desert is considered.

Acid fracturing, as a conventional and effective stimulation method, has been widely used in carbonate formation. But because of serious acid leak-off and rapid acid/rock reaction speed, the length of effective acid etched fracture is always restricted, even the high viscosity acid and emulsified acid were applied; besides, the effective duration of etched fracture was short, especially in deep well. The propped fracturing can supply longer fracture and long-term effective duration, but its ability of connecting natural fracture or fissure is poor because the fracturing fluid is unreactive with the formation. So the propped fracturing with a novel surface cross-linked acid (SXA) is proposed, because it can not only realize long fracture length/deep penetration, but also connect more natural fracture/fissure to maximize the permeable area as possible. In order to realize the technique, a novel temperature-stability and shearing resistance delayed cross-linked acid (SXA) was developed to qualify for the fracturing treatment. Meanwhile the effect of HCl on one high strength ceramic proppant was also studied, and the results showed the crush resistance and conductivity of proppant is unaffected. So the SXA and the acid- resisting proppant provide the basis for acid propped fracturing, and a comprehensive fracturing technique was developed. Acid propped fracturing with SXA was processed in the carbonate formation with depth > 5000m and temperature >140℃. A volume of 36.2m3 proppant was successfully pumped into the formation with the maximal proppant concentration exceeding 450kg/m3. The net pressure matching indicated that the propped fracturing created long conductive fracture and realized deep penetration. The new technique provided a new and broader option of carbonate stimulation.

The KKY in Tarim oilfield, Western China, is a typical HTHP deep dolomite reservoir (150C, 110Mpa and 6000m). The formation was deeply damaged with the heavy mud, and the matrix acidizing can't effectively eliminate the skin. But the acid fracturing treatment can't be carried because the surface pressure exceeds the working pressure capability of conventional 15,000psi fracturing equipment. To effectively decrease the surface treating pressure, a new high density acid system was developed. Its density is adjustable within the range of 1.25-1.55 g/cm3. Extensive laboratory test was conducted to evaluate its corrosion inhibition capacity, stability, rheological properties etc. The performance of the acid system can totally qualify for the need of high temperature, and effectively lower the surface treating pressure about 25Mpa. The new weighted acid ensured the acid fracturing successfully in KKY reservoir, with the treating pressure up to 94Mpa. And the production increased considerably after the acid fracturing with the high density acid in several wells.

A successful case of proppant fracturing on an ultra-high pressure (Pressure gradient 0.018MPa/m), deep (5725-5783m) sandstone gas reservoir in Western China is described in this paper. Several technologies including high density(density1.12g/cm3) frac-fluid, high density(density 1.25g/cm3) flush-fluid, proppant slug, multi-step slurry injection schedule, real time analysis were used. 20-40 mesh 28.5m3 proppant was injected into the payzone successfully. The result is encouraging. The production reach to 307,000m3/d after the treatment. The project is a technical and economical success. The lessons acquired in the well will be a reference for the following similar wells.