This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 208443, “Integrity Evaluation and Management in High-Temperature, High-Pressure, and High-Production-Rate Wells in Southwest China,” by Dajiang Zhu, Yu Fan, and Huali Zhang, PetroChina, et al. The paper has not been peer reviewed.
The Longwangmiao (LM) gas field in southwest China features high-pressure (HP; approximately 75–76 MPa), high-temperature (HT; approximately 144–156°C), and high-production-rate (approximately 700 000–1 million m3/d) characteristics. Serious well-integrity problems were encountered in the development process. Wellhead growth was present in 33 wells, and four wells exhibited gas leakage through wellhead valves. A well-integrity-management system was developed based on annulus-pressure-management technology, wellhead-growth-risk analysis and control, downhole leakage detection, and wellhead corrosion and erosion detection, ensuring the safe and stable production of gas wells.
In the four wells that experienced gas leakage after well completion, this mainly consisted of damage to and leakage of the wellhead valve stem seal, tail rod, and flange connection (Fig. 1). In addition, corrosion and internal leakage in six wellhead valves with a material level rating of FF also was detected. The corrosion and leakage of wellhead equipment has become a restrictive factor for the rapid and safe development of the gas reservoir. In addition, because the average gas-production rate of a single well is greater than 700 000 m3/d, and the wellhead temperature is greater than 90°C during production, the wellhead generally is lifted. After the gas reservoir was put into operation, under the influence of the rise of wellbore temperature, 33 of the 56 production wells were monitored for wellhead growth. The average growth was 4 mm for production wells, and the maximum value was nearly 30 mm.
