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In our country there is plenty of CBM (coalbed methane), but the state of CBM itself, unique output mechanism and low saturation, low permeability, low reservoir pressure and high gas content, et al. determine the low efficiency of it, so in order to improve CBM recovery, combined with the successful experience of north American shale gas reservoir by SRV(stimulated reservoir volume), the writer summarizes the implementation of SRV, deeply analyzes effectiveness and limitations of this new technology in CBM development. The results of practical research and theoretical analysis show that SRV in the coal reservoir can achieve the desired effect on the condition that there are great quantity of natural fractures, joints and bedding, weak structure surface development in the reservoir, the rock brittleness index is greater than 40 and horizontal principal stress difference is relatively smaller. Finally, simulating a well’s condition by the MEYER software, the result shows that SRV is feasible in coal reservoir, which will create important guiding significance and practical value for the exploration of CBM.

Based on the size effect of rock strength, the borehole stability analysis model is established, which the borehole size is taken into consideration. Through this model, the relation between borehole size and collapse pressure under borehole pressure, ground stress and drilling fluid flow function is analyzed. The analysis shows that with the increase of borehole diameter, collapse pressure increases significantly, and borehole stability becomes poor, but the variation of borehole size is not proportional to collapse pressure: the bigger the borehole, the smaller the variation. When borehole diameter increases from 152.4 mm to 444.5 mm, wellbore collapse pressure increases from 1.18g/cm3 to 1.315g/cm3 and the rate of the increase is 11.44%. When slimhole drilling technology is applied, the density of minimum fluid that maintains wellbore stability is lower than the one used in conventional wellbore drilling.

As the oil or gas exploration and development activities in deep and ultradeep waters become more and more, encountering gas hydrate bearing sediments (HBS) is almost inevitable. The variation in temperature and pressure can destabilize gas hydrate in nearby formation around the borehole, which may reduce the strength of the formation and result in wellbore instability. A non-isothermal, transient, two-phase, and fluid-solid coupling mathematical model is proposed to simulate the complex stability performance of a wellbore drilled in HBS. In the model, the phase transition of hydrate dissociation, the heat exchange between drilling fluid and formation, the change of mechanical and petrophysical properties, the gas-water two-phase seepage, and its interaction with rock deformation are considered. A finite element simulator is developed, and the impact of drilling mud on wellbore instability in HBS is simulated. Results indicate that the reduction in pressure and the increase in temperature of the drilling fluid can accelerate hydrate decomposition and lead to mechanical properties getting worse tremendously. The cohesion decreases by 25% when the hydrate totally dissociates in HBS. This easily causes the wellbore instability accordingly. In the first two hours after the formation is drilled, the regions of hydrate dissociation and wellbore instability extend quickly. Then, with the soaking time of drilling fluid increasing, the regions enlarge little. Choosing the low temperature drilling fluid and increasing the drilling mud pressure appropriately can benefit the wellbore stability of HBS. The established model turns out to be an efficient tool in numerical studies of the hydrate dissociation behavior and wellbore stability of HBS.

Hydraulic fracturing is one of the effective means to enhance coal bed methane production for vertical wells. This paper presents an approach that uses pseudo-3D fracture propagation model to study the influence of petrophysical properties, differential stress, treatment conditions, etc. on fracture geometry. It is shown that differential stress, pump rate is proportional to fracture length and width; elastic modulus, Poisson`s ratio, pump rate, etc. is proportional to fracture height. The finding is of great importance for acquiring ideal fracture geometry.

As a kind of emerging energy with massive reserves, natural gas hydrates are becoming the hot spot of global research. The elastic properties of gas hydrate bearing sediments (HBS) are the fundamental parameters for gas hydrates exploration and resource evaluations. As the original coring in HBS is difficult and expensive, experimental method is important to study the problem. An acoustic wave in-situ measuring system for HBS was developed. Using the in-situ method, hydrate bearing rock samples of different hydrate saturation were synthesized, of which the supersonic wave measurement was carried out under different confining pressure. According to the elasticity theory, the dynamic elastic parameters were obtained using the measured ultrasonic wave velocity. The results show that compressional and shear waves increase with the confining pressure and hydrate saturation increasing, and so the dynamic elastic modulus is.

On the basis of low permeability exploiting statement, “Exploding in fracture” is present in this paper and the feasibility and safety of this technology is also analyzed. It is found that the rock damage and fracture by shock wave in “Exploding in Fracture” can be simulated by the experiment of exploding on the surface of the cement sample in deep water. The damage and fracture of the cement sample, and the wave propagation proceed, and the damage and fracture mechanism are described qualitatively. It is found that the micro-fractures and compacted wave have an intimate relationship with the initial damage of the sample. The numerical simulation result is accordant with the experiment result. It also concluded that the qualitative explanation of rock damage and fracture mechanism is right. The compacted damage zone has definite permeability, which has an important means to “Exploding in Fracture” technology.

The application of well logging data is one of the most common prediction methods of pore pressure. According to acquire the field practical applicability and high accuracy, Eaton’s method proposed a definition of area index which can present the local complex factors resulting in abnormal pressure regardless of overpressure generating mechanisms. However, the computed area index is generally calculated by one layer in the whole formation, thereby generating some prediction errors. This paper presents a new method called “Hierarchical Eaton’s Method” that is considering different computed area indexes from different layers. Therefore, the revised Eaton’s method can have higher accuracy comparing to traditional Eaton’s method. Moreover, the application of this new method in HPHT wells in Yinggehai basin, China has been discussed in this paper and indicates the field feasibility of this approach.

International tension between energy supply and demand boost developments of energy-saving industry. Structure drawbacks of four linkage bar of the conventional beam pumping unit in oil field artificial lift led to the study of a single crank flexible pumping unit. Because of beam pumping unit issues, such as many energy transfer links, high energy consumption and investment, and so on, the single crank flexible pumping unit made the flexible delivery instead of rigid, substantially reduce the energy transfer links, to reduce the weight of the load rod as a breakthrough to achieve light and compact oil production ground equipment, while minimizing energy consumption, increased functionality, lower investment and overall cost. Field tests show that significant energy savings are found in the single crank flexible pumping unit, which is worth of promoting.

Room temperature photoluminescence (PL) has been observed from Er doped silicon rich silicon oxide films grown by magnetron sputtering. For all kinds of silicon rich silicon oxide films grown with different excess Si contents, each PL spectrum has two peaks at 1.54 and 1.38μm, which originate from Er3+ and a certain kind of defects, respectively, in the silicon rich silicon oxide. It was found that 1.54 and 1.38μm PL peak intensities are correlated with each other. The PL intensity-dependence on the excess-Si content and annealing temperature was studied in detail.