If there is an oil pipeline running through your property owned by someone else, most likely there is an easement that burdens your parcel. I recommend that you get a copy of your deed and review it carefully as well as any preliminary report concerning the state of legal title. From it you should be able to ascertain what easements there are burdening your property. Once ascertained, go to the county recorder's office and pull up copies of the easements (assuming your property has some recorded upon it) for review.Just because there is an oil pipeline running through your land, it does not necessarily mean that oil is being pulled from your property. The tell tale sign would be if there was an oil derrick pumping oil on your land.Given the circumstances that you have written, I recommend that you consult with a real estate attorney experienced in mineral rights and easements to further assist you.If the pipe is going to be replaced shortly, I suggest that you consult with the people who will be doing the job about your concerns about the fence line and the horses.