A Case Study: Innovative Open Hole Well Completion Provides Superior Results in Tight Gas Formation in Jilin District, China

摘要

Drilling of horizontal wells has increased steadily over the last few years in China on land. As technology has developed, operators have seen the economic and production benefits of drilling horizontally. In the Changling gas field, the Deng Louku formations are primarily low porosity (average 5.2%) and low permeability (average 0.17md) tight sand. Typically, wells in this area are drilled vertically and completed with cemented casing. Proppant fracturing was necessary to produce the well economically due to the low permeability nature of the formation. However the production results from the conventional vertical fracturing completions were not very promising and most of the wells experienced rapid production decline once they were put on production. Thus it became crucial to find an engineering solution to effectively unlock the reserves and obtain sustained long term productivity. Multistage fracturing of the DP2 horionatal well is a milestone for the operator due to: 1) the deepest, and most stages in a single horizontal well in a tight sand formation in China was completed and fractured; 2) the biggest fracturing job for a single well in terms of proppant and fracture fluid volume was successfully pumped continuously by first time application of the precise continuous mixer (PCM) in China; 3) an innovative multistage fracturing design workflow was developed to optimize the horizontal well completion design including several disciplines: geology, reservoir modeling and fracturing. This workflow was set as the standard design process for multistage fracturing design in the field. The DP2 horizontal well was completed in ten stages in the 837 m openhole section and the ten fracturing stages were pumped continuously in 3 days. The PCM was used to improve the fracturing operation efficiency. A total of 1425 tons of 30/50 proppant was successfully placed into the formation using 4870 m~3 fracturing fluid. The well produced 320,000 m~3/day initially and was stabilized at 180,000 m~3/day with 20 MPa wellhead pressure, which is 5 times higher than the average offset well. The application of real time hydraulic fracturing monitor technology helpped to verify that the optimized fracture half-length was achieved, and to adjust the fracturing schedule in real time for the second stage.