Maturing oil-and-gas fields are characterised by the increased presence of water, restricted production and increasing greenhouse gas emissions. Both single-phase and multi-phase pumps (MPPs) have been used successfully to boost production from low-pressure wells. However, the use of conventional multi-phase pumps incurs huge capital and running costs.
Among all pumping methods, one of the most simple and effective ways to retrieve oil from low pressure wells or boost production from such wells is via the use of surface jet pumps (SJPs).
The SJP can be used for the pumping and mixing of fluids within a wide range of applications across many engineering sectors. In the oil-and-gas industry, in contrast to other improved oil recovery (IOR) and enhanced oil recovery (EOR) solutions, the SJP technology can be a cheap and effective solution. Usually the field requirements determine whether a JP should be designed to handle liquid, gas or a mixture of liquid-gas on either of the two inlets (for motive flow and production flow).
SJPs have been commercialised for use with both single-phase and multi-phase flows, but conventional SJPs have disadvantages where the motive fluid contains more than a single-phase, such as a liquid and gas mixture as there can be a reduction in production flow. This makes them unpopular and these devices can have limitations in their applicability due to lack of flexibility, rangeability and versatility, which precludes subsea applications and is problematic for remote onshore and offshore locations.
Cranfield University has developed a novel jet pump apparatus to supplement oil flow without the need for a separate electrically powered booster pump. Jet pumps are based on the Venturi principle and use available high pressure lines to provide a motive flow to generate suction at the well head, and therefore are energy efficient and, having no moving parts, require low maintenance. A major drawback though of existing jet pumps is that they choke up rapidly if the high pressure line contains a mixture of liquid and gas. Cranfield University’s novel pump design incorporates a compact, integral phase separator and enables it to work effectively under a wide range of motive fluid conditions with mixtures of liquid and gas, without interrupting production flow.
Above: Schematic of a typical surface jet pump apparatus, illustrating its components. Please note, image is purely illustrative.
The new type of pump has significant advantages over existing jet pump configurations, potentially offering:
- Increased production;
- Reduced downtime due to slugging;
- Lower capital costs for installation;
- Removes need for heavy and large upstream separator units;
- Compact and easily placed in confined locations;
- Stable and operates effectively with wide range of high pressure fluid mixtures and compositions;
- Lifts the total proportion of oil recovered from end-of-life reservoirs.
Relative increases of 117% and 160% in entrainment performance have been achieved with gas volume fractions (GVFs) of 0% and 35% respectively compared to conventional SJPs. As well as increased overall performance, a wider range of operability enables the JP to handle multi-phase driving fluids with GVFs in the range 0% < GVFs < 50% with continuous operation.
The novel surface jet pump apparatus can be used for:
- Enhancing production oil flow with a direct high pressure multi-phase source without an upstream separator unit;
- Compressing flare gas for recovery;
- Installations on remote operated platforms;
- Sub-sea installations and unmanned remote locations.
Cranfield University has a track record of research and commercial projects related to oil-and-gas production and the University benefits from near-industrial facilities, including a unique and fully automated high-pressure multi-phase flow loop, the largest among all UK universities’ facilities.
Cranfield is seeking expressions of interest from industrial partners wishing to utilise the know-how on design and operation of the novel SJP to realise new products.
Licensees and potential users of the technology are invited to get in touch.
UK (GB2571135A) and PCT applications (WO2019162649A) are in progress with priority date of 20 February 2018.
Intention to grant GB2571135A has been notified and the International Search Report for WO2019162649A contains no serious issues (9A citations only), so equivalent national phase patents are expected to be granted.
- Development collaboration.
Above: Figure 1 - Entrainment ratio (low pressure flow/high pressure total mixed flow) vs. high pressure fluid gas volume fraction. A comparison between a JP of 'conventional-design', and the novel JP with swirl induced flow.