Reservoir Management Section provides support across most of the subsurface, drilling, facility engineering disciplines and makes a major contribution in terms of how we manage, field performance, production volumes, reserves recovery, and the utilisation of equipment and operational techniques that minimise environmental impact. – to edit
KPO is currently drilling 8 wells per year to complete the phase IIM for a total program of 36 wells. There are nearly 388 wells of varying categories in the Karachaganak field, of which 94 are producing wells and 17 are gas injectors as of end 2013. The remaining wells either form part of an extensive network of monitoring and observations wells or are abandoned exploration or production wells.
KPO currently has two drilling rigs and one work over rig (2 frac units, 2 coiled tubing units and 3 clean-up and testing units), and when needed a specialist small rig works in the field undertaking a variety of activities in support of the on-going Phase IIM development of the field. Innovations in drilling applied by KPO in the Karachaganak field represent best world technologies and include the following:
- Multilateral Wells
- Flareless Well Testing & Clean Up
- Digital Oilfield
- Open Hole Packers and Variable Down Hole Chokes
- Intelligent wells’ completion
KPO has also drilled some of the most complicated wells in Kazakhstan, including multi-lateral wells with both two and three branches. The longest multi-lateral well has a main bore and two branches that are 521, 591 and 471 metres long respectively.
Because of the heterogeneous nature of the Karachaganak reservoir, drilling multilateral wells in Karachaganak enables a larger area of the reservoir to be contacted from a single well for relatively low incremental cost. This increases the productivity of the wells. Both selective and non-selective completions have been run, the selective completions enable independent well tests to be carried out on each branch of the multilateral well.
It is common oilfield practice to test new wells so as to evaluate their capacity to flow before connecting them to the surface production facilities. This serves several purposes which include measuring basic parameters that are needed to model the initial performance of the well, evaluating the drilling efficiency and comparing actual to predicted productivity.
The test involves flowing the well at several stable rates which are measured by a portable test separator attached to the well. In the separator the effluent from the well is subjected to a large pressure drop which allows the individual phases to be separated (oil and gas in the case of Karachaganak) before the phase rates are measured. Historically the products of the separation process are flared using highly efficient burners which limit liquid dropout in the area around the well.
Given the need to ensure environmental protection, operators, together with leading service companies, have development methods to reduce and eliminate flaring during these well tests.
In March 2008, the Mega Flow separator, developed by Expro, was mobilised at Karachaganak as part of KPO’s efforts to minimise environmental impacts. This unique piece of equipment allows the phase separation to take place at higher pressures which means the rates of the oil and gas can be measured and then recombined and redirected into the production flow line. Not only does this avoid all flaring but the hydrocarbon recovery helps mitigate the cost of using the equipment.
More recently, following numerous upgrades to the metering of the separators in the surface facilities, these tests are carried out directly in the processing plant after the well flow line has been connected to the production facilities.
The Digital Oilfield project will provide an integrated platform from which various departments can virtually interface on issues related to the operations of Karachaganak. Teams involved in day to day operations will have access to real time data which will enable more efficient and productive operations.
The Drilling Support Centre (DSC), opened in April 2009, is a key part of the broader Digital Oilfield project. The DSC facility is a self-contained control centre with real time collaborative working environment for the operations engineers and other stakeholders. The advanced software used in this facility will help to implement drilling optimisation and monitoring services in real time. Live data from each rig is streamed to the centre allowing online communication and effective performance management.
Oil recovery in Karachaganak has many challenges. Two of the main ones are:
- Reservoir turns out to be very heterogeneous and compartmentalized in the bottom zone that contains the oil;
- Oil is volatile and its gas content increasing with time is bottlenecking the facilities.
In general the upper zones of the reservoir, bearing lighter oil or gas condensate, have a natural tendency to produce better than the lower ones. Formation and fluid characteristic distribution might lead to the impossibility to produce the oil from some of the lower part of the reservoir.
To mitigate this risk two different concepts have been introduced in the well completion in Karachaganak: Open Hole Packer completion (swelling technology has been selected) and Variable Down Hole Chokes for fluid entry control. The first allows producing/injecting fluid in/from selected zone of the open hole, improving production fluid management and stimulation efficiency (for increasing the movement of the oil towards the well even in poor part of the reservoir); the second for limiting the gas condensate contribution to the minimum necessary to maximize the oil production. Open Hole Packer completion has successfully increased the stimulation efficiency in more than one well and is now used even to mitigate the risk of undesirable fluid production (formation water). First Variable Down Hole Choke has been included in the completion of a well recently Worked Over.
Intelligent completion technology is designed to optimize well production and reservoir management processes by enabling operators to remotely monitor and control well inflow or injection downhole, at the reservoir, without physical intervention. Intelligent completions consist of some combination of flow control and zonal isolation devices, downhole control systems and surface facilities. There are such benefits of this method like reduction in the surface facilities and costs compared with traditional artificial lift methods, production optimization with changing bottom hole completion configuration (reservoir conditions) without the requirement for well intervention or workover.