Successful Recovery and Stimulation in a Long HP/HT Horizontal Well in One Intervention
Authors: Carpenter Chris 
Published: April 2018

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 188567, “Successful Recovery and Stimulation of a Long HP/HT Horizontal Well in One Intervention: A Case History of Acid Fracturing and New Generation of Diversion Systems Combination, Middle Marrat Carbonate Formation,” by Leopoldo Sierra, Alaa Eldine Alboueshi, Mohamed Elmofti, Walid Eid, Salma Sadeddin, and Ahmed Allam, Halliburton, and Mohamed Al Othman, Zamzam Ahmed, Erkan Fidan, Ibrahim Al-Zaidani, Neoq Nilotpaul, Meshari Ashkanani, Ali Buhamad, Mohammed Abdullah Al-Dousari, Abdul-Samad Mohammed Ahmed, and Yousef Al-Matrouk, Kuwait Oil Company, prepared for the 2017 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 13–16 November. The paper has not been peer reviewed.

The case history presented in the complete paper describes the performance of an acid-fracturing intervention in a high-pressure/high-temperature (HP/HT) well in which this intervention was the last procedure considered to evaluate the productivity of a Marrat Formation well. The post-acid-fractured well productivity index (PI) showed the high quality of the stimulation performed in a challenging environment, demonstrating the effectiveness of the new diversion system for creating selective fractures in a horizontal wellbore with multiple perforation clusters.

Introduction

Completion of deep HP/HT carbonate formations in northern Kuwait in overpressured environments comprising interbedded carbonate bodies, complex tectonics, and stress variations resulting in strike/slip or reserve fault regimes is challenging for operator and service companies. Because of the low-permeability conditions, it is necessary to generate long and conductive fractures to produce the reservoir effectively. Additionally, this aggressive fracture- stimulation requirement needs to overcome the high-working-pressure limitations of the completion, in addition to the nature and corrosiveness of the produced hydrocarbon, which makes se-lection of the proper stimulation reactive-fluid system important.

These challenges are even more crucial in cases having drilling and completions issues. The alternative implemented for the well candidate presented in the complete paper considers the completion and stimulation of a well having an existing long perforated interval, where the implementation of a selective fracture stimulation of a highly deviated wellbore (88° or almost horizontal) was challenging.

Geology, Reservoir, and Geomechanics of Middle Marrat Formation

The Marrat reservoir is subdivided into three lithostratigraphic units: Lower, Middle, and Upper. The well candidate was drilled and completed to produce hydrocarbon reserves from the Middle Marrat Formation. The Middle Marrat unit represents a wide range of rock types related to high-stand precursor facies in a carbonate setting, which is overprinted by diagenetic alteration in refluxed and recrystallized dolomites. Eight gross flow zones have been identified bounded by major sequence-stratigraphic surfaces that frame the background of genetically correlated units.

Reservoir quality and vertical connectivity can be controlled further by placing properly distributed hydraulic fractures, vertically and laterally, to connect the prospective reservoir and existing natural-fracture networks to improve hydrocarbon recovery.