Novel Coiled-Tubing Perforation Technique and Stimulation in Carbonate Gas Well
Authors: Carpenter Chris 
Published: July 2017

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 18880, “Novel Abrasive Perforating With Acid-Soluble Material and Subsequent Coiled-Tubing Jetting-Assisted Stimulation Provide Outstanding Results in Carbonate Gas Well,” by Adrian Buenrostro, Nahr Abulhamayel, Usman Malik, Mohammad Bu Suwaileh, and Saad Driweesh, Saudi Aramco, and Alejandro Chacon, José Camilo Jimenez Fadul, and José Noguera, Halliburton, prepared for the 2016 International Petroleum Technology Conference, Bangkok, Thailand, 14–16 November. The paper has not been peer reviewed. Copyright 2016 International Petroleum Technology Conference. Reproduced by permission.

Abrasive perforating with coiled tubing (CT) is a technique that has proved to be a valuable alternative to conventional perforating with electric line. The application is particularly valuable whenever a high rate or fracture-stimulation treatment is to follow because of the significant reduction in tortuosity and pumping friction losses across perforations. This paper discusses a novel approach to abrasive perforating, including the first-ever use of an acid-soluble abrasive material and ending with CT-jetting-assisted nitrified stimulation.

Introduction

Many carbonate gas wells located in the northern section of the Ghawar reservoir exhibit a low-permeability profile and are characterized by having low reservoir pressure. Fracture gradients in a formation in this area of the field are on the order of 1.12 psi/ft, which is considerably greater than that of more-conventional tight gas formations. One particular well, located on the flank of the reservoir, was designed to be completed with a plug-and-perforate acid-fracturing operation, but issues arose with this option that finally caused the abandonment of the fracturing treatment. To find a solution that would be feasible and economically viable, an innovative perforation and stimulation technique was engineered for this well.

Design of the Perforation Technique and Yard Testing

The team was able to source a newly developed acid-soluble abrasive material that enabled the same quality of perforations to be created without performing a cleanout run because the acid from the stimulation would dissolve the abrasive material, saving at least 2 days of operation.

The abrasive material was sourced, and several yard tests were completed to determine if the material had the same abrasive characteristics as common 20/40- or 100-mesh sand. It was necessary to compare the time required to penetrate the steel and cement with the results obtained using common sand. This benchmarking was key to determining if additional time and fluid resources were necessary to obtain the same penetration.

A yard test was set up with two metallic 55-gal drums cut halfway lengthwise and then welded together. This created a receptacle that allowed the team to place a 6⅝-in. casing section with 100% standoff and then fill the entire annular space with cement. The drum was then set on top of cement blocks, and the abrasive-jetting tool was introduced.