Dear Ms. Gifford,
The first question that comes to mind is was an actual survey done on the property? If so, who granted permission for them to enter? Without permission, they are in trespass.
Equally (or more) important is the easement agreement itself. A wonderful article was written by Eric Camp. A copy is located here: http://www.mineralrightsforum.com/profiles/blogs/pipeline-easement-and-right-of-way-agreements-a-landowner-s-list
In West Texas, most pipeline companies will want to use a comparison to the University School Lands Damage Schedule. A copy of that schedule is located here: http://www.utlands.utsystem.edu/forms/pdfs/rate_damage_schedule.pdf
NOW, you have a floor. The school land schedule lists the minimum that they will accept. There is no maximum. Also, the school land will not have an easement with a term longer than 10 years without a renegotiation. We tend to negotiate in terms of multiples of the school lands floor.
To give you an idea on recent negotiations that I have had in Reeves and surrounding counties in the past 6 months or so.
$196 per rod initial. 10 year renewals at $150 per rod, using a CPI escalation. Limit of 5 renewals.
$345 per rod, perpetual
$165 per rod for a 4"line
As to your question as to appraisals, be very careful that you do not shoot yourself in the foot. An appraisal is for the value of the property, in acres. That is not the measure of damage. The measure of damage is the highest and best use of the land. Also, if there is not an existing line that they are following, there is collateral damage to the balance of the property by the fact that there is a pipeline transversing the property.
Location of the line is very important. You want the line to follow the property or fence line if possible rather than the bifurcation of the acreage.
There are a lot of factors that come into play -- way too many to discuss here. Most pipeline companies will pay for your lawyer or negotiator (or at least part of it).
Also, it is best to slow the negotiation to a crawl. Time is on your side. As they get closer to the construction date, then they likely will raise the rate that they will pay to seal the deal. I have negotiated several easements that were within hours of suit being filed.
You have to have courage to play this game.