Abstract
Reservoir stimulation with high anisotropy presents a challenge that various diversion techniques can address, including relative permeability modifiers (RPMs), nitrogen, and ball sealers. In vuggy carbonate reservoirs with high-permeability contrast, these diversion techniques often lose effectiveness, which makes mechanical isolation the preferred approach. Coiled tubing (CT) inflatable packers (IPs) have been widely used as one of the principal methods for mechanical isolation. However, their main limitations include setting depth accuracy, single-set capability, permanent deformation of the packer element, and restricted flow path options. The first global multi-set application of a fully electric inflatable packer (e-IP) deployed on CT is presented. The e-IP uses a 4-mm cable (five fiber optics plus a copper conductor) and downhole sensors to ensure precise placement of the element in a narrow area.
The operation involved two CT runs. The first run used a high-efficiency jetting nozzle for casing conditioning and included a modular- sensing bottomhole assembly (MSBHA) to validate downhole conditions for the next run. After the downhole pressure was confirmed, final adjustments were made to the e-IP based on the maximum differential pressure and the ideal inflation pressure of the element for the next run. The second run deployed the e-IP bottomhole assembly (BHA) to conduct the acid stimulation. This assembly included the MSBHA, which used a gamma ray (GR) and casing collar locator (CCL) for depth correlation with a downhole pressure sensor to measure inflation pressure and calculate delta pressure (DP) in the tool, and to track the formation response to the acid. Weight on bit (WOB) confirmed that the packer anchored and monitored any abnormal behavior of the element throughout treatment.
The e-IP features a unique running tool that provides access to and switches between different flow paths after the packer is set. The available flow options include:
Above the packer: pump through the CT to spearhead acid into tight reservoirs
Below the packer: pump through the CT
Above the packer: pump down the annulus
The real-time hybrid coiled tubing (RTHCT) system, equipped with an ultracompact MSBHA [pressure (P), temperature (T), CCL, GR, WOB, torque, inclination, tool face, and vibration] and an e-IP, exhibited stellar performance as a mechanical diversion method in high- permeability contrast reservoirs. The system executed three successful set/unset cycles in a single run. One of the setting cycles which was not initially planned at the start of the operation but was implemented based on real-time diagnostics provided by the MSBHA, demonstrating the flexibility and multi-set capability of the e-IP.
The multi-set capability, combined with a diagnostic suite of sensors, reduces the number of runs and operational time required for accurate treatment placement. In operational environments where uncertainty is inevitable, the real-time decision-making capability of this tool combination enables appropriate actions during a single trip; therefore, time and total operational costs can be reduced.
