^^ Vaginal lubrication is overwhelmingly blood plasma, so we can approximate the calorific value over that. Plasma is 7% protein and 0,084% sugar (90 mg/dl over 1,06 g per ml). Proteins and carbohydrates are both ~4kcal/g. The fat content is roughly 0,47%, which is about 9 kcal/g. Add that together and you get 32,5 kcal/100 g. (Main Source)
In other words, to satisfy the caloric (but not nutritional) needs of an average adult woman of about 2 Mcal, you would need to consume 6,153 kg or 5,8 l of vaginal lubrication.
Mucus around ovulation might impact that value, but I can't find detailed breakdowns of its composition.