“Squimulation”—Simultaneous Well-Stimulation and Scale-Squeeze Treatments in Deepwater West Africa

Abstract

Summary In a deepwater west African field, the relatively small number of high-cost, highly productive wells, coupled with a high barium sulfate scaling tendency (upon waterflood breakthrough of injected seawater) requires effective scale management along with removal of near-wellbore damage in order to achieve high hydrocarbon recovery. The nature of the well-completion strategy in the field (frac packs for sand control) had resulted in some wells with higher than expected skin values owing to drilling-fluid losses, residual fracture gel, fluid loss agents, and fines mobilization within the frac packs. The paper will present how the challenges of managing impaired completions and inorganic scale forced innovation in terms of when to apply both stimulation and scale-inhibitor packages to deepwater wells. This paper will outline a novel process for non-conventional batch chemical applications where bullhead stimulation treatments have been displaced deep into the formation (>20 ft) using a scale inhibitor overflush. Not only does this benefit the stimulation by displacing the spent acid and reagents away from the immediate wellbore area, but the combined treatment provides a cost savings with a single mobilization for the combined treatment. The paper will describe the laboratory testing that was performed to qualify the treatments. The four field treatments that were performed demonstrate how these coupled applications have proven very effective at both well stimulation/skin reduction and scale-inhibitor placement before and after seawater breakthrough. The term “squimulation” is used by the local operations team to describe this simultaneous squeeze-and-stimulation process. Many similar fields are currently being developed in the Campos basin (Gulf of Mexico) and west Africa, and this paper presents a good example of best-practice sharing from another oil basin.

Progress on the relationship between miR-125 family and tumorigenesis

“…Both of them have a negligible sulfate content of less than 20 mg/l to cause significant sulfate scaling (Ramstad et al 1999, Fleming 2010, Patterson et al 2013 …”

The state of the art in scale inhibitor squeeze treatment

“…This procedure was used proactively at the early stage of the well development to address the early scale problem of seawater breakthrough at low water cut in offshore wells where treatments are expensive. Such simultaneous treatment has been applied to the Gulf of Mexico and West Africa wells with good squeeze life (Jordan 2012;Patterson et al 2013Patterson et al , 2014. Lastly, a phosphonate scale inhibitor has been successfully incorporated into a seawater-based, borate-cross-linked frac fluid for frac pack operations as a preempt measure (Marquez et al 2011).…”

Scale Inhibitor Squeeze Treatment Design in an Acid Stimulated Carbonate Reservoir

“…On the one hand, SI may be included within the stimulation fluid (Jordan, 2012) or applied as "squimulation" where the stimulation fluid is displaced by the squeeze treatment; this has been successfully applied in sandstone reservoirs (Patterson et al, 2013). Among these two applications, squimulation is recommended, since if the SI is placed with the stimulation fluid, extra precipitation with phosphonate SI will occur which can lead to formation damage (Jordan, 2012).…”

“…The model considers one dimensional two-phase flow transport in radial coordinates (Vazquez et al, 2012). The model has been extensively used to simulate squeeze treatments in the field (Bogaert et al, 2007;Vazquez et al, 2011;Mackay and Jordan, 2003;Patterson et al, 2013;Jordan, 2013). Since the model is one-dimensional the SI propagation is radially around the wellbore, therefore it is necessary to evaluate how deep the SI propagates into the matrix to account fully the wormholing effect on the squeeze treatment lifetime.…”