A Field Applications of Effective Stimulation High Pressure/Temperature Multi-Stage Completion which Shows Significant Well Performance Improvement in Deep North Kuwait Jurassic Unconventional Reservoir

摘要

Selecting the completion design and stimulation technique in North Kuwait Jurassic Gas (NKJG) were critical to overcome reservoir challenges by stimulating these unconventional formations efficiently and effectively. Therefore, the completion design must be high-pressure rated upto 15,000 psi, high temperature of 275°F and sour service specified because of high H2S & CO2 content. These reservoirs are heterogeneous carbonate type with various productivity index due to existence of natural fracture which needs proper completion type that treat each reservoir layer separately. The most challenging factor in these unconventional reservoirs is the high permeability contrast among the different flow units because of the dual porosity effect which needs convenient diversion mechanism during the stimulation. The reservoir was segmented into different intervals to enhance the productivity index of each flow unit. For that reason, "High Rate Matrix Acidizing (HRMA)" method was obtained with retardard acid to restore the well productivity due to the drilling fluids which alter the effective permeability near the wellbore. By dividing each flow unit into separate stages across packer system and stimulate them subsequently is the aim to overcome high permeability contrast across the reservoir flow units. The Monobore Multi-stage was chosen as a completion type to produce from different zone of interest. These Reservoirs are divided into different stages and acid treated with various stimulation techniques (Acid fracturing & High Rate Matrix Acidizing). The success of the stimulation treatment in monobore Multi-stage completion depends on several factors such as: selecting proper fluid recipes, rock/fluid properties, job design, and field implementation. That type of completion is activated as a drop-ball system to stimulate each flow zone individually but in single well intervention setup. This paper presents a 15K open-hole HPHT MSC field success case application that describes the best practices, learning, planning, design, installation and stimulation in NKJG unconventional reservoirs to enhance well performance and overcome reservoir challenges. An improvement in understanding of production performance from several reservoir sections is the key enabler selective stimulation and effective testing. After stimulating all the stages milling of the ball seats of completion was obtained in order to pinpoint well production profile. The post stimulation flow tests results and production logs provided a good evidence for applying this technology these unconventional reservoirs.