Sui Gas Field, being the largest and oldest among the company’s assets, has been injecting gas into the national gas network since 1955. The estimated ultimate recovery of Sui reservoirs is around 12.4 TCF and during more than six decades, around 11.5 TCF gas has been produced. The reserves as of December 31, 2020, stand at 0.9 TCF with a current production share of around 54 percent of the company’s operated fields’ gross gas production.
The field has faced several challenges, both operational as well as on the management side due to the recent drop in international oil prices coupled with an ageing field, production decline, lower gas price, increasing operating costs and security challenges.
To address this production decline enigma and arrest the historical 7 percent annual decline, numerous subsurface activities have recently been undertaken with an aim to tap every opportunity for production enhancement and improve the overall recovery. These include a range of complex workovers for reinstatement of low producers: including the side track of Sui 64(M) & Sui-29(M) towards the zone with better productivity & low water saturation, tubing size optimization in Sui 36(M) & Sui 40(M), and conversion of Sui 28(M) (watered out well) into a Sui Upper Limestone (SUL) well. Moreover, for the first time in Sui, high rate high pressure acid stimulation was done on two wells - Sui 103(U) and Sui 106(U), to connect the wells with nearby fracture network.
New horizons in the Pab reservoir were also explored, with Sui 95(P) and Sui 108(P) adding around 30 MMscfd to Sui field’s portfolio
Using the same In-house Integrated field model, the Sui Field Gas Compressor Station (SFGCS) was also analyzed, to evaluate the field’s overall performance and identify the Technical and Economic field life. Currently, the SML Compressors are running at 6+1 configuration i.e. 06 compressors are in parallel operation, while 01 is on standby. It has been identified that the suction pressure limit of the current Compression system would reach by June 2022. After that, successive shutdown of the compressor trains would be required, to avoid surging and maintain the suction pressure at 7 barg. Therefore, a revamping project for the compressors has also been approved, which will be executed in two phases to distribute the project cost without impacting the reserves and field life. This compression revamping project will add around 238 BCF in 1P while 291 BCF in 2P portfolio, which is more than three times the company’s total reserves replenished in 2018-19 and almost equivalent to the replenishment in 2019-20. The NPV of the field will also increase by around US$15.5 million - calculated at 12% of weighted average cost of capital (WACC).
Further, overhauling of purification plant banks, boiler and dehydration unit has improved reliability and restored their capacity. These operations also helped ensure uninterrupted supply of gas to customers.
The HSE standard and Asset integrity of facilities has been improved in the recent past despite Sui being an aging field. The asset’s HSE KPI has been satisfactory and improving even with current growing activities at well sites, field and plants. Lost time Injury frequency remained zero against the target of 0.07 and near miss reporting has improved and well above the target.
Overall, Sui asset has been able to deliver outstanding results due to the continuous focus, commitment and teamwork displayed by its management and staff. The production decline has been significantly reduced; and currently, the YTD production is 2.3 percent higher than budget.
The Kandhkot Asset (KA) looks after the overall operations of Kandhkot and Chachar gas fields, undertaking reservoir studies, carrying out field economics, reservoir surveillance, well intervention/ work over and completion for production enhancement, as per work plan. This also includes operation, maintenance and debottlenecking of plant, wells and surface facilities.
The asset also manages budget, plans and executes work programs to ensure sustainable production and maximum ultimate recovery from the field to achieve set targets. The team is also responsible for exploring new horizons for maximum gas off-takes and maintaining uninterrupted supply of natural gas to customers in-line with GSA. KA Asset also manages matters with Joint Venture partner for Chachar Gas field.
As part of the asset-based structure, KA is headed by General Manager [Sui & KA], who leads a multidisciplinary team of professionals, including production engineers, reservoir engineers, geoscientists and field operations staff. Besides, the team also focuses on optimizing production and recovery from the two fields by applying cutting edge technology and international best practices