A method for evaluating gas saturation based on a three-detector pulsed neutron logging instrument and its application
Tight gas reservoirs have been one of the important field of gas exploration and development and the dynamic monitoring of gas saturation is of great significance to adjustment of oilfield development scheme.Pulsed neutron logging technology plays an important role in the evaluation of gas saturation in cased holes.The low porosity of tight gas reservoir presents a new change to the application of pulsed neutron logging technology.In order to further excavate the measurement information of pulsed neutron logs and improve the sensitivity of gas saturation, the Monte Carlo numerical simulation method was used to study the gas saturation response of different parameters obtained by the instrument.The results show that by adding an extra far gamma-ray detector to the traditional pulsed neutron logging instrument, the sensitivity of the measured information to gas saturation is improved.The ratio of near capture gamma-rays counts to extra far capture gamma-ray counts mainly depends on hydrogen index of the formation and the ratio of near inelastic gamma-ray counts to extra far gamma-ray counts greatly affected by the change of formation density.Combining the response characteristics of the two parameters, a method using the difference between them is proposed to determine gas saturation.Compared with the conventional macroscopic capture cross section method, the new method improves the sensitivity of gas saturation response under low porosity conditions and is less affected by the variation of the salinity of formation water.
Feng Zhang Juntao Liu Jun Song Yong Huo Lili Tian
School of Geoscience, China University of Petroleum, Shandong Qingdao 266580 CNPC Logging Tarim Business Division, Xinjiang Korla 841001
国际会议
西安
英文
169-180
2017-09-20（万方平台首次上网日期，不代表论文的发表时间）