Productivity Evaluation and Trial Production Design Methods for Saddle Well with Multi-Layer Commingled Production in Edge-Bottom Water Sandstone Condensate Gas Reservoir

The trial production design of condensate gas reservoirs is mostly conducted by drilling new well in high structural position. However, sometimes it needs to conduct trial production design based on evaluation well in the structural saddle especially when the investment and industrial chain surplus capacity were limited. Therefore, this paper systematically presented the design methods of productivity evaluation and trial production in a condensate gas reservoir with edge-bottom water. The dry layer distribution was identified through DST analysis, logging and geophysical interpretation. Combining DST data for productivity evaluation and well testing interpretation, the absolute open flow rate (AOF), physical parameters and boundary characteristics of four gas layers were analyzed. The binomial productivity equation was applied to back-calculate the permeability compared with the logging interpretation value, and use the productivity evaluation method after acidification measure to re-calculate the AOF. Combining analogy analysis with numerical simulation, the discount coefficient of AOF under the conditions of commingled production was determined to guide the reasonable productivity design. The development technology policies and monitoring suggestions were finally proposed. Based on in-depth analysis of dynamic and static data, it has been confirmed that the main layer at the top, Lower Nia, has a dry layer with 30-40m thick. The influx of bottom water can be greatly delayed by further optimizing the perforation scheme. The permeability of Upper Noi interpreted by logging, well testing, and binomial productivity equation is relatively low, mainly due to the influence of fractures and mud invasion, and causing a significant reduction in the actual gas production contribution thickness. Lower Noi is a low resistivity gas layer with high clay content. Ene at the bottom has a high AOF and significant gas production contribution, and it can be treated by placing mature bridge plug for water blocking. Based on the derived discount coefficient of AOF, reasonable commingled productivity and perforation schemes of all four layers were designed, and monitoring suggestions for PLT and combined-layers well testing analysis were proposed. This paper systematically presents the design methods of combined productivity and trial production process based on one saddle well for a typical condensate gas reservoir with edge-bottom water, which can provide important references for low-cost trial production design of similar gas reservoirs.