The objective of this paper is to explain the best practice adopted in exploration while perforating & testing of shallow unconsolidated sour heavy oil reservoirs & challenges faced during first testing phase and the adopted strategy for development of the field and during wells production phase with available solutions.
Cold flow testing method using PCP was used to test heavy Oil (°API, 15-21) bearing unconsolidated formation of low GOR with 5-18 % H2S, formation pressure 250-430 psi at depth 400-850 ft. In testing campaign, different testing intervals were perforated with 4.5", 5spf, 0.47" EHD gun and tested with low capacity PCP chosen to handle the anticipated challenges acquired from drilling, logging and MDT sampling data. Individual tests in 4 wells, proved huge potential of the field. Based on the IPR, Extended Commingle test was done with bigger PCP and achieved around 1000 BPD, this boosted confidence in the newly discovered project to develop and produce commercially.
Highly encouraged from initial testing and extended commingle cold flow test, Phase-II was approved for development and production. 20 wells were drilled and 15 were successfully tested utilizing higher capacity PCP, different perforating guns were utilized to minimize sand production, single & multi-layers tests were performed. The problem of sand production with several pump stuck becomes a challenge requires more frequent well cleaning operations. Few wells were completed with Insert PCP to avoid requirement of a W/O rig or pulling unit. 7 wells were completed with bigger pumps and put on production, but early formation water production surfaced as a major challenge. Based on current experience from both the phases, a low capacity PCP, lower shot density guns with medium EHD is being considered to minimize sand problem which was a success during initial testing. Testing using sand screen is another option under consideration. Also, a low rate production in range of 300 bpd is being considered. Different combinations of perforating system, PCP size and optimum production rate are under consideration to minimize the challenges & maximize field productivity. New surface testing equipment set up & combination of new technology was implemented for fine sand handling & higher flow measurement accuracy.
For the first time in Kuwait, cold flow test using PCP was a remarkable success for initial testing of highly sour shallow unconsolidated reservoir the field is being developed and produced simultaneously. Low rate production, suitable PCP and perforating system used during initial testing of each well is the key for way forward for the project. A combination of suitable PCP, implementation of sand screens, best suited perforating gun and suitable rate of production will maximize the oil recovery.