Mechanical sand control completions are often used to optimise hydrocarbon production from weak formations. In a few wells this primary sand control method has sub-optimal performance. There is substantial value in remediating some of these wells, but developing this capability is not a quick and simple task. Recompleting a well could be feasible, but is often cost prohibitive. Mechanical solutions could be applied to stem sand production if the sand producing interval is known; however, in some cases chemical sand consolidation is the most effective approach. Chemical sand consolidation works by pumping chemicals downhole to strengthen the formation and stop sanding. In most cases reported in the industry, chemical consolidation has been used in short production intervals (<100m). Our approach was to develop a laboratory programme to test various industry chemicals and to achieve a good understanding of how these can be applied. Candidate wells were matched to chemicals to identify which systems (may be more than one) would be the best fit. The strategy was to initially trial the technology in low-rate onshore wells (typically <1 mmscf/d), before moving progressively to more challenging wells (up to 2,500 bopd). The wells were split into 3 groups based on their complexity: (1) proppant flow back remediation, (2) <100m producing interval and (3) >100m intervals. Each has unique challenges, but this approach facilitated a progressive learning curve. In proppant flow back remediation 7 field applications were conducted with 100% success rate. Longer intervals were successfully treated over time. Matrix consolidation presented a bigger challenge - 10 field trials have been carried out with a mix of successes and failures. A key learning is that adequate placement of the chemicals is critical. Chemical sand consolidation would fulfil its potential only when the chemicals can be reliably delivered to the target sand-producing zone – (often unknown), and remain static to allow sufficient curing time. Some treatments have been bullheaded (i.e pumped down the production tubing); others have been placed with coiled tubing. Operator has successfully developed an organisational capability whereby this technology can be part of the toolkit and - where appropriate - can be applied with a reasonably high chance of success to add value. Wells have been treated in the Lower 48 states in the USA, Canada, Alaska, Azerbaijan and Egypt and other wells are constantly being evaluated. Well types include oil and gas producers, onshore and offshore, with reservoir temperatures from 29 °C to 135°C. This technology is therefore being used across a wide well portfolio.
The reliability of the production is essential in offshore operations. Producing a well at its maximum rate is important everywhere. This is often compromised by having sand and fines production which not only plugs the wells and reduce production rate but also erode the equipment and settle in surface vessels. This paper describes a case history where an operator was faced with a well that was rate limited because of fines and sand production. An advanced sand control chemistry system was proposed and a treatment was designed. In April 2013, the treatment was performed by bullheading down the production tubing using rate diversion. Extensive engineering was involved in the candidate selection and planning the operational aspects of the treatment. The execution of the treatment was divided into stages – sand clean out, performing step rate test, pre-job modeling and pumping the treatment as per the design. After the treatment, the well was flowed and tested at almost three times the original maximum sand-free rate (MSFR) at an increased choke without sand production. The well has now been flowing for more than a year, at significantly higher rate than the previous MSFR sand free. This paper describes the chemistry of the sand conglomeration, design consideration, execution and the effect on well performance.
This article investigates the use of a commercial latex dispersion for the purpose of sand consolidation in oil wells. The aim is to consolidate sand without compromising permeability and to prevent sanding during water breakthrough. This is achieved by injecting latex dispersions into a sand-pack and relying on potassium chloride flushes, or irreducible saline water in the reservoir, to destabilise the latex onto the sand surface. This forms a latex network connecting and holding the sand grains together. The strength of the consolidation in the laboratory is determined by flowing water and oil at various flowrates and investigating the amount of sand produced. The effect of different parameters, such as the amount of latex injected, the latex salinity and salinity of the irreducible water are discussed.
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