In recent years, field development strategies have begun to prioritize horizontal well technology over vertical and deviated wells because of the advantages of maximized reservoir contact, higher production rates, and better access to available hydrocarbon reserves. Some of the horizontal wells completed with openhole wellbores in carbonate formations are actually stable and good producers when the reservoir permeability is sufficiently high to not require a large or complicated stimulation treatment. If the permeability is low (i.e., less than 10 mD), as in most cases, this type of completion challenges any type of acid stimulation because of the well architecture and resulting poor distribution of the stimulation fluid over the entire lateral section. The Mishref reservoir of the Minagish field, located in western Kuwait, is a tight carbonate formation with poor reservoir quality and relatively low reservoir pressure; it was completed conventionally with openhole wellbores. The acid stimulation treatments performed in this area that showed positive results led to the selection of a multistage acid fracture stimulation of shorter horizontal wells. To enhance production in this field, the lateral length of the horizontal wells has been increased; the increased length, however, has also increased the challenges associated with proper stimulations if these issues are not considered during the completion stages of the wells. To maximize and sustain hydrocarbon production in long horizontal open holes, a multistage acid fracturing stimulation is still required if selective tools are used to complete the openhole section. The selective completion tools enable the mechanical segmentation of the annular space of the wellbore by dividing it into the required small isolated intervals based on petrophysical and reservoir properties. The isolated sections can be selectively stimulated to maximize the productivity in one continuous intervention. This paper summarizes the design processes, stimulation challenges, production response, and lessons learned from one multistage acid fracturing stimulation performed on a well drilled and completed in the Mishref reservoir of the Minagish field. In this well, the entire 1,800-ft length of the openhole lateral was divided into seven isolated stages by using swell packers and sliding sleeves. Because of the architecture and nature of the wellbore and the requirement to generate long fractures to properly drain the reservoir, the isolated compartment length (distance from the swell packers isolating the stage) was reduced to an average of 106 ft, and a sliding sleeve was placed in the middle of isolated sections. The paper documents the pilot multistage acid fracturing treatment on this type of completion; it also demonstrates the success of the stimulation in that the outcome exceeds the expected production increase, resulting in a more sustained production, as compared with the offset wells.

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A significant challenge in the tight Mishrif oil reservoir of the Minagish field is ensuring hydrocarbon flow through the complex and highly damage-susceptible carbonate intervals. In recent years, field development strategies have begun to prioritize multilateral well technology over vertical and deviated wells because of the advantages of maximized reservoir contact, higher production rates, and improved access to reserves (hydrocarbon in place). The downside of most unconventional multilateral wells is that laterals are open hole, completed with much complexity, and pose challenges for effective acid stimulation because of poor acid distribution over the long interval. The Mishrif formation in the Minagish field in west Kuwait is a challenging tight carbonate with poor reservoir quality, relatively low pressure, and no external pressure support. The stimulation methodology was highly modified as fit-for-purpose to address the unique challenges of multilateral well operations, formation technical difficulties, high-stakes economics, and untapped potential from these formations. Furthermore, to enhance production, the lateral lengths of the well were designed as an optimum solution. To maximize and sustain hydrocarbon flow and production, a multiple stage acid pinpoint treatment was performed by dividing the wellbore into small intervals, based on petrophysical and reservoir properties evaluations; a high-rate pinpoint technique was used for both laterals individually. The selected sections were individually acid stimulated, and the inflow contribution from the entire productive sections of both laterals was maximized with a highly reliable and effective multistage continuous operation. The post-operation well test and production data show a significant production increase; long-term production data show a sustained production increase, stable pump intake pressure, and low water cut, demonstrating the success of the pinpoint technique as an optimized solution for the first multilateral well. The success of this well stimulation method has enabled the use of this pinpoint-squeeze as the best technique for all horizontal wells in this field. This paper summarizes the design processes, challenges encountered, production response, and lessons learned from applying this pinpoint acidizing technique. It can be considered as a potential approach for addressing stimulation challenges in similar tight carbonate reservoir conditions in other fields.