Depending where your acreage is located along this long county line, PT Petroleum, Amistad and Approach Operating are the operators who have permitted wells in past 1.5 years in this area.
This southern part of the Midland Basin is not as active (and as yet, successful) as areas to the north near Midland / Odessa, Big Lake and Big Spring. The western Upton / Crockett Co line area has some thermal maturity concerns (i.e. the section has not been heated sufficiently to create a good unconventional reservoir situation). The central and eastern parts of the county line are productive but to a lesser extent than the northern areas due to issues such as clay content, section brittleness and a more gassy reservoir, All these factors impact horizontal drilling economics.
I would suggest that, with a 14,000 acre block, you should be able to attract interest from operators who are not already in the area. This size of block is significant - and based on the geology in that area, some operators may want to take a shoot at leasing this block.
There is some activity in Yoakum County but it is highly variable across the county. Need to know the area of your 650 acres before commenting on who is active in that area.
All this info can be gleaned from the Tx RRC site - if you are wanting to stay up on industry activity, well results and who is doing what in which areas, this free site is the best resource to get comfortable with using.
Here is the link to the main Tx RRC site: