You may need to consider whether the lease is HBP with multiple wells and so it will not expire even if there is no lease amendment. It may be older lease which doe snot have a pooling provision and that is what Pioneer wants. In exchange, you can ask for increased royalty rate or for cost-free royalties. Also, you do not have to agree to a lease amendment allowing any and all pooling. Instead you can simply consent to a single pooling for a particular well with limited acreage and terms in DPU. Be careful that DPU does not grant the operator the ability to change any and all terms without your (lessee's) consent. Limit your consent to specified acreage and depths/formation. Consulting an oil and gas attorney is a good idea. But even that depends on your net mineral acreage and interest in the well. If you only own 1 acre then the considerations are different than owning 100 acres.