基于统计分析的最优救援井数量及救援成功率研究

钻井平台发生井喷、爆炸等事故,如果不能在短时间内完成封堵救援作业,将造成巨大的经济损失和严重的环境污染。为实现在有限的救援条件下用最短的时间完成封堵救援作业,根据统计学原理,基于“骰子游戏”建立“时间-累积封堵成功率”模型,分析了尝试封堵次数、连通工具的性能(封堵成功率)、平均钻井时间、救援井数量、救援井的启动时间对累积封堵成功率的影响。另外,结合“深水地平线”事件的救援方案验证了该模型的实用性。研究表明,针对不同的井喷事故类型,“时间-累积封堵成功率”模型能够结合现场的基础设备、人力资源及关键技术等条件推算出最合理的救援井数量和救援井的启动时间,为制定救援井方案提供理论支持。

群井降低地下水位的新措施

结合工程实践应用,介绍群井降低地下水位的新措施,由于改变了以往在基坑上口开挖边线外布井,采取在基底开挖边线外布井,不仅减少了造井深度,而且大幅度地降低了排水量,减少了造井数量,从而加快了施工进度,降低了工程成本。

乾安县地下水开采井布局及井距

乾安县是以开采地下水为主的商品粮产区之一,近几年来,随着国家抗旱资金的大力投入,各类的开采井逐年增加,在现有的地下水可开采量的情况下,文中就对开采井进行科学的布局,选择合理的井距,确定打井数量,充分发挥水资源的综合效益进行了论述。

地温中央空调系统提水及回灌井设计方案探讨

为节能、降低消耗、减少废弃物排放，利用地下水水源的水温潜能作为地温空调系统的冷、热源，以实现为建筑物制冷和供热目的提供技术参数依据。因此本文通过抽水及回灌试验所获成果计算含水层的渗透系数及回灌渗透系数，从而使中央空调井的设计合理，并求得最佳抽、灌井数量比及合理布井方案。

Study of S-wave ray elastic impedance for identifying lithology and fluid

In this paper, we derive an approximation of the SS-wave reflection coefficient and the expression of S-wave ray elastic impedance （SREI） in terms of the ray parameter. The SREI can be expressed by the S-wave incidence angle or P-wave reflection angle, referred to as SREIS and SREIP, respectively. Our study using elastic models derived from real log measurements shows that SREIP has better capability for lithology and fluid discrimination than SREIS and conventional S-wave elastic impedance （SEI）. We evaluate the SREIP feasibility using 25 groups of samples from Castagna and Smith （1994）. Each sample group is constructed by using shale, brine-sand, and gas-sand. Theoretical evaluation also indicates that SRE1P at large incident angles is more sensitive to fluid than conventional fluid indicators. Real seismic data application also shows that SRE1P at large angles calculated using P-wave and S-wave impedance can efficiently characterize tight gas-sand.

A novel method for predicting breakthrough time of horizontal wells in bottom water reservoirs

Dimensional analysis and numerical simulations were carried out to research prediction method of breakthrough time of horizontal wells in bottom water reservoir. Four dimensionless independent variables and dimensionless time were derived from 10 influencing factors of the problem by using dimensional analysis. Simulations of horizontal well in reservoir with bottom water were run to find the prediction correlation. A general and concise functional relationship for predicting breakthrough time was established based on simulation results and theoretical analysis. The breakthrough time of one conceptual model predicted by the correlation is very close to the result by Eclipse with less than 2% error. The practical breakthrough time of one well in Helder oilfield is 10 d, and the predicted results by the method is 11.2 d, which is more accurate than the analytical result. Case study indicates that the method could predict breakthrough time of horizontal well under different reservoir conditions accurately. For its university and ease of use, the method is suitable for quick prediction of breakthrough time.

DEM simulation of confining pressure effects on crack opening displacement in hydraulic fracturing

Hydraulic fracture is one of the key methods in well stimulation to increase production of oil and gas.Crack Opening Displacement(COD) is of great importance in this method since it is in direct relation with permeability and production rate.In this paper COD is measured by a distinct element model which has been validated by an exact solution.A comprehensive study has been performed on confining pressure effect on COD which is neglected in the analytical solution.Numerical results showed that confining pressure considerably affects COD.A multi-parameter regression(considering effect of confining pressure,rock mass properties and fluid pressure) was performed on numerical results which resulted in an equation.The proposed equation considers the effect of confining pressure and its results are in good agreement with numerical results.

A practical application of photogrammetry to performing rib characterization measurements in an underground coal mine using a DSLR camera

Understanding coal mine rib behavior is important for inferring pillar loading conditions as well as ensuring the safety of miners who are regularly exposed to ribs. Due to the variability in the geometry of underground openings and ground behavior, point measurements often fail to capture the true movement of mine workings. Photogrammetry is a potentially fast, cheap, and precise supplemental measurement tool in comparison to extensometers, tape measures, or laser range meters, but its application in underground coal has been limited. The practical use of photogrammetry was tested at the Safety Research Coal Mine, National Institute for Occupational Safety and Health(NIOSH). A commercially available, digital single-lens reflex(DSLR) camera was used to perform the photogrammetric surveys for the experiment. Several experiments were performed using different lighting conditions, distances to subject,camera settings, and photograph overlaps, with results summarized as follows: the lighting method was found to be insignificant if the scene was appropriately illuminated. It was found that the distance to the subject has a minimal impact on result accuracy, and that camera settings have a significant impact on the photogrammetric quality of images. An increasing photograph resolution was preferable when measuring plane orientations; otherwise a high point cloud density would likely be excessive. Focal ratio(F-stop) changes affect the depth of field and image quality in situations where multiple angles are necessary to survey cleat orientations. Photograph overlap is very important to proper three-dimensional reconstruction, and at least 60% overlap between photograph pairs is ideal to avoid unnecessary post-processing. The suggestions and guidelines proposed are designed to increase the quality of photogrammetry inputs and outputs as well as minimize processing time, and serve as a starting point for an underground coal photogrammetry study.