Investigation of tight carbonate reservoir for possibile acid fracturing.

摘要

An investigation behind possible reasons for deteriorating injectivity of field A peripheral water injectors below their initial set individual target rates is carried out. This is followed by an assessment of the possibility of improvement in injectivity with acid fracturing and recommendation to apply acid fracturing.;The scope of the investigation included reviewing water particle size, effect of matrix stimulation jobs in restoring well injectivity and ability of the well to sustain retained injectivity until it drops back to pre-stimulation conditions. Also effect of the horizontal hole length on injectivity was reviewed by looking at data from the longest horizontal hole drilled in ADCO and other wells in the field.;Review of field daily injection rates, history of matrix stimulation, length of horizontal section and injection intake across its intervals backed by reservoir management evaluation tools such as the ABC and Hall plot assisted in fulfilling the project objectives. A literature review is dedicated to horizontal well design, matrix stimulation, acid fracturing and relation between regional stress and fracture geometry as well.;The study proposed acid fracturing as an alternative approach to improve well daily injection rate. A process established by selecting a candidate well, the use of 2-D fracture geometry model followed by use of well performance software application aided in exploring optimum daily injection rates possible. Sensivities were investigated to assess possible scenarios.;Field A is one of the fields operated by Abu Dhabi Company for Onshore Oil Operations (ADCO). Located in the onshore area, about 110 km to the southeast of Abu Dhabi Island is an elongated, faulted, double plunging anticline structure with the longer axis trending roughly northeast-southwest. It is about 30 km long and 10 km wide and its flanks at the top Thamama level dip 3 to 5 degrees on the western and eastern side, and 1 to 2 degrees on the northern and southern sides.