A New Concept of Chemical Sand Consolidation: From Idea and Laboratory Qualification to Field Application

Abstract

The conceptual idea is to give the porous matrix of the formation some additional residual strength to enhance the maximum sand free rate (MSFR). Sand production in weakly consolidated reservoirs will occur when tensions in the well/perforation tunnel walls are large enough to disrupt the binding between the individual sand grains. This will generate a plasticized layer of sand in the near well bore area. The layer will erode by the produced fluid and be transported to the surface. The rate of erosion will depend on the residual strength of the plasticized zone and of the hydrodynamic forces acting on that particular zone. There is field evidence indicating a residual strength corresponding to the capillary force in water-wet sand to be sufficient in stopping or limiting the sand production substantially. Thus, only a small increase in residual strength of the plasticized sand would make large contribution for enhancing the MSFR. This will have large economical implications in fields with wells controlled by MSFR, and particularly in the decline phase in which the field is well controlled by the well potential. Since the criteria for strength are quite low, search for potential treatment chemicals could be carried out in areas completely different from the traditional chemicals used in sand consolidation. Three different chemical systems have been investigated and one chemical has been brought further for laboratory qualification and field use at a North Sea Field. In order to carry out a full field test, challenges regarding water contamination, long horizontal wells with difficult placement and zonal coverage, and complex polymerization mechanisms in the carrier fluid had to be addressed. Some of these challenges and field experiences will be presented and discussed to gain valuable knowledge for future chemical sand consolidation operations. Introduction Sand production from oil and/or gas producing wells is a problem in many parts of the world [1–3]. Sand production causes erosion of process equipment and disposal of the sand causes environmental problems, especially offshore.The active sand control has mainly focused on screens [1, 4–8], gravel packing [9] and perforation techniques [10, 11] to prevent sand production. All these methods include heavy hardware and tools being a large part of the cost of a new well. For poorly consolidated formations, chemical sand consolidation can be an alternative to the traditional techniques. In particular for sub sea developments where conventional interventions are expensive, chemical methods can be a competitive remedial alternative. Chemical sand consolidation has been in use since the early 1940's [12]. Quite a lot of research has been done on epoxy and furan systems, especially in the 1960's [12–21]. The prior art of chemical sand consolidation is to make "rock" from sand, in other words to increase the strength of the matrix to a large degree. The basic idea of the present work is to only increase to the residual strength of the formation by a small amount. In order to prove this new idea, a laboratory study was undertaken to evaluate different chemicals for sand consolidation. The chemicals used can be divided into three different groups based on the consolidation method:Chemicals that are based on organosilane chemistry,chemicals based on polymers andan enzyme derived method based on precipitation of CaCO3 (s). The chemicals were tested with regard to their ability to reduce sand production compared to reference experiments. The best overall chemicals for sand consolidation seemed to be the organosilanes. These chemicals aim at reducing the effect of tensile failure and hydrodynamic erosion of the formation matrix, two aspects of sand production that are especially important for unconsolidated formations. One of the organosilanes was further qualified for field application.

Chemical Sand Consolidation: From Polymers to Nanoparticles

“…Rising water-cuts also affect sand production in a way that drops the relative permeability of oil over time after the production, thereby raising the pressure drop and inducing stresses, required to flow the well at the desired production rate, then yielding sand production [3]. Some researchers categorize the Chemical methods on the other hand can be an alternative approach to control the unconsolidated formation that produces a myriad of sand [11]. The chemical sand consolidation methods, (namely plastics, have been used to control sand production since early 1940 [19].…”

“…Capillary forces act as a stabilizing force for these arches [9,10]. The arches can fail because of the tensile failure criterion [5,11]. Sand production can occur because of reservoir formation damage.…”

“…Chemical methods on the other hand can be an alternative approach to control the unconsolidated formation that produces a myriad of sand [11]. The chemical sand consolidation methods, (namely plastics, have been used to control sand production since early 1940 [19].…”

Polyacrylamide hydrogel application in sand control with compressive strength testing

“…However, mechanical methods are often time-consuming and costly in the production process (Kotlar et al 2008). Chemical methods are an alternative method for a poorly consolidated formation that produces a lot of sand (Kotlar et al 2005). These methods were implemented based on the injection of chemical components around the wellhead to consolidate the formation rock to reduce the further movement of sand grains (Maduabuchi et al 2017).…”

“…In this approach, fluid injection must be implemented at the desired time at which the production rate exceeds a critical value (Bellarby 2009). Besides, the chemical method can be carried out in two ways: by oxidation of a hydrocarbon material that saturates the sand around the wellbore (Aggour and Abu-Khamsin 2004) and injection of polymeric or non-polymeric components into the formation rock (El-Sayed et al 2001;Kotlar et al 2005Kotlar et al , 2008Wasnik et al 2005).…”