he carbonate reservoir has tight lithology and is operated at high temperature in S block. In order to improve the oil recovery, it is necessary to carry on the acid fracturing treatment to the target reservoir. According to the characteristics of the target reservoir, the acid fluid for acid fracturing was optimized and evaluated. Through the porosity and permeability experiment, the porosity of S block was 0.1%~2.0%, and the permeability was below 0.01 mD, which belonged to ultra⁃low permeability reservoir. According to the uniaxial compression test, the compressive strength of the reservoir was high, ranging from 40 to 70 MPa. X⁃ray diffraction showed that dolomite and calcite were the main minerals in the reservoir ( 80%~90% in total), with a small amount of quartz and clay (mass fraction was about 10%). The main acid was 20% hydrochloric acid, the thickener was 0.3% xanthan gum, and the dissolution rate of rock powder was about 90% when hydrochloric acid acted alone, and the main acid solution was hydrochloric acid. Taking into account that the reservoir lithology of carbonate rock in S block was dense and the formation temperature was 100~140 ℃, the viscosity of modified xanthan gum was about 10 mPa·s at 140 ℃. The modified xanthan gum was selected as high temperature resistant thickener.

Land-based petroleum spills have the characteristics of sudden occurred, large amount and fast speed of leakage, and wide pollution area, which have caused serious lasting damage to terrestrial ecosystems. This paper summarized the harm of land-based petroleum spills to soil environment and human health, and a method of dealing with oil spills was introduced, including physical and chemical adsorption of inorganic mineral materials and immobilized microorganism treatment technology. In addition, the study focused on the in-situ remediation of land-based petroleum spills in cold environments of China, and the physicchemical adsorption and microbial degradation were organically combined. Besides, the combination of fly ash based zeolite and immobilized microorganisms gave full play to the advantages of high adsorption efficiency of inorganic mineral adsorbent and complete degradation of coldadapted petroleum degrading bacteria. The study can provide scientific basis for treatment of land spilled petroleum under cold environments.

Interaction between three surfactants and hydrophobically associating watersoluble polymers (HAWP) were studied. The experimental results show that the interactions differ according to the types of surfactants. Viscosity increases and interfacial activity decreases for the interaction of alkanolamide or petroleum sulfonate and HAWP, while viscosity decreases and interfacial activity remains consistent for the interaction of betaine and HAWP. With the increase of substituent carbon numbers, interactive force decreases between sulfonates and HAWP, and increases between betaines and HAWP. The force sequence of interaction between surfactants and HAWP is alkanolamide,sulfonate,betaine under the same low substituent carbon numbers. 

The accuracy of a flowmeter is influenced greatly by the flow field structure in the natural gas pipeline. The numerical simulation was introduced to study the flows in a natural gas pipeline. The flow fields in a diffusive pipeline with different rectifiers were computed as examples. The result show that the length of the irregular flow induced by the diffuser is abut 17 times of the pipe diameter. The effect of a rectifier is obvious. The length of the irregular flows with a plate rectifier is about 12 times of the pipe diameter. The length of the irregular flows induced by the diffuser with a tube rectifier is about 6 times of the pipe diameter. The conclusions will be very useful for the flowmeter selection and installation. It provides a new method for the study of improving the natural gas measurement accuracy.