Development dynamic monitoring technologies used in the Puguang high-sulfur gas field

Abstract

There is lack of performance monitoring technologies and related standards and specifications in the Puguang gas field, which is ultra-deep with high sulfur content. In this paper, five key technologies of dynamic monitoring were developed and the related standards and specifications were formulated by investigating high-sulfur gas fields at home and abroad, combined with equipment development, laboratory experiments, theoretical research and field tests. The five key technologies include gas production profile logging, downhole sampling and fluid phase analysis, dynamic water invasion prediction and water producing horizon identification, gas well productivity testing and evaluation, and development monitoring and safety control of high-sulfur ultra-deep wells. Then, these key technologies were applied for verification in the Puguang gas field. And the following research results were obtained. First, the sulfur-resistant gas production profile logging tool has a temperature resistance of 175 °C and pressure resistance of 105 MPa. Forty-three well times gas production profile logging is carried out with a success ratio of 100%. Second, the high-sulfur downhole pressure sampler has a temperature resistance of 150 °C and pressure resistance of 70 MPa. Seven well times downhole pressure sampling is carried out with a success ratio of 100%. Third, elemental sulfur is precipitated in the formation when the formation pressure drops to 29.5 MPa. And no sulfur is deposited in the wellbore when the production rate of gas well is higher than 20 × 104 m3/d. Fourth, water producing horizons can be identified accurately and water breakthrough time of gas wells can be predicted by using water producing horizon identification technology and dynamic water invasion prediction model. Water influx rates can be controlled and water-free gas production period of gas wells can be extended by optimizing and adjusting the working systems of gas wells. And fifth, full coverage of gas well productivity testing is realized by using the testing technology of "downhole implanted gauge & cable delivery & wellhead flow-variable rate", pressure calculation model and well testing interpretation model, and the productivity evaluation results of gas wells are accurate. Sixth, the dynamic gas tight pressure of the cable multi-stage leakage control system of super-high pressure and gas tightness is 50 MPa, and the processing technology for waste gas of blowout hookup is applied to 143 well times testing operation with zero leakage and zero pollution. In conclusion, these performance monitoring technologies have been playing an important role in scientifically formulating the production and reserves increase measures and ensuring long-term stable production of the Puguang gas field.